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  • 1.
    Albrectsen, Benedicte R
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Witzell, Johanna
    Robinson, Kathryn M
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Wulff, Sören
    Luquez, Virginia MC
    Ågren, Rickard
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Large scale geographic clines of parasite damage to Populus tremula L2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, no 3, p. 483-493Article in journal (Refereed)
    Abstract [en]

    In conclusion, clines of Phyllocnistis were stronger and more persistent compared to Melampsora, which showed contrasting clines of varying strength. Our data thus support the assumption of the GMTC model that clines exist in the border between hot and cold spots and that they may be less persistent for parasites with an elevated gene flow, and/or for parasites which cover relatively larger hot spots surrounded by fewer cold spots.

  • 2.
    Andersson, Erik
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Bodin, Örjan
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Practical tool for landscape planning? An empirical investigation of network based models of habitat fragmentation.2009In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, no 1, p. 123-132Article in journal (Refereed)
    Abstract [en]

    This study presents a graph-theoretical modelling approach using daily movements and habitat demands of different target bird species in an urban context to assess: 1) habitable land cover types, 2) threshold distances between patches of habitat, 3) the required minimum accessible habitat areas and 4) the effects of barriers and stepping stones. The modelling approach is tested using empirical data from field surveys in the urban area of Stockholm, Sweden.

    The results show that groups of small habitat patches can house the same species as larger contiguous patches as long as they are perceived as functionally connected by the inhabitant organisms. Furthermore, we found that binary habitat/non-habitat representations of the landscape could roughly explain the variation in species occurrence, as long as habitat was properly defined. However, the explanatory power of the landscape models increased when features of matrix heterogeneity such as stepping stones and barriers were accounted for.

    Synthesis and application: in a world where forest ecosystems are becoming increasingly fragmented there is an urgent need to find comprehensive and scientifically relevant methods for managing and planning ecosystems. This study shows that: 1) groups of well placed small habitat patches can, together, be sufficient to attract birds in intensively developed areas, 2) the presented modelling approach can help identify such groups of patches, 3) matrix heterogeneity should preferably be accounted for, and 4) proper assessments of habitable land cover types are important. Finally, we argue that the modelling approach applied here may substantially improve landscape management and planning at scales ranging from whole landscapes down to neighbourhoods.

  • 3.
    Angerbjörn, Anders
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Tannerfeldt, Magnus
    Stockholm University, Faculty of Science, Department of Zoology.
    Lundberg, Håkan
    Stockholm University, Faculty of Science, Department of Zoology.
    Geographical and temporal patterns of lemming population dynamics in Fennoscandia2001In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 24, no 3, p. 298-308Article in journal (Refereed)
    Abstract [en]

    There is a long-lasting debate in ecology on cyclicity, synchrony and time lags of lemming population fluctuations. We have analysed 137 yr of previously published population data on the Norwegian lemming Lemmus lemmus in ten geographic regions of Fennoscandia. The dominating pattern was synchronous 4-yr cycles. There was no support for the hypothesis of a north-south gradient in cycle length. However. we found periods of prolonged interruptions in the cyclicity, which were more common in northern areas. Wa found a high degree of synchrony between regions. with only a weak relationship to distance, The observed pattern in lemming population dynamics was more consistent with effects from extrinsic factors, such as climate. than intrinsic factors. such as dispersal.

  • 4. Aston, Eoghan A.
    et al.
    Williams, Gareth J.
    Green, J. A. Mattias
    Davies, Andrew J.
    Wedding, Lisa M.
    Gove, Jamison M.
    Jouffray, Jean-Baptiste
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Royal Swedish Academy of Sciences, Sweden.
    Jones, Timothy T.
    Clark, Jeanette
    Scale-dependent spatial patterns in benthic communities around a tropical island seascape2019In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 42, no 3, p. 578-590Article in journal (Refereed)
    Abstract [en]

    Understanding and predicting patterns of spatial organization across ecological communities is central to the field of landscape ecology, and a similar line of inquiry has begun to evolve sub-tidally among seascape ecologists. Much of our current understanding of the processes driving marine community patterns, particularly in the tropics, has come from small-scale, spatially-discrete data that are often not representative of the broader seascape. Here we expand the spatial extent of seascape ecology studies and combine spatially-expansive in situ digital imagery, oceanographic measurements, spatial statistics, and predictive modeling to test whether predictable patterns emerge between coral reef benthic competitors across scales in response to intra-island gradients in physical drivers. We do this around the entire circumference of a remote, uninhabited island in the central Pacific (Jarvis Island) that lacks the confounding effects of direct human impacts. We show, for the first time, that competing benthic groups demonstrate predictable scaling patterns of organization, with positive autocorrelation in the cover of each group at scales < similar to 1 km. Moreover, we show how gradients in subsurface temperature and surface wave power drive spatially-abrupt transition points in group dominance, explaining 48-84% of the overall variation in benthic cover around the island. Along the western coast, we documented ten times more sub-surface cooling-hours than any other part of the coastline, with events typically resulting in a drop of 1-4 degrees C over a period of < 5 h. These high frequency temperature fluctuations are indicative of upwelling induced by internal waves and here result in localized nitrogen enrichment (NO2 + NO3) that promotes hard coral dominance around 44% of the island's perimeter. Our findings show that, in the absence of confounding direct human impacts, the spatial organization of coral reef benthic competitors are predictable and somewhat bounded across the seascape by concurrent gradients in physical drivers.

  • 5.
    Auffret, Alistair G.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Cousins, Sara A.O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Grassland connectivity by motor vehicles and grazing livestock2013In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, no 10, p. 1150-1157Article in journal (Refereed)
    Abstract [en]

    In addition to habitat loss and fragmentation, agricultural change has led to a change in seed dispersal processes in therural landscape through a loss of structural and functional connectivity. Here, human-mediated dispersal vectors areprevalent, and we explored whether the loss of connectivity via free-ranging livestock could be mitigated by the increasein roads and motor vehicles. We found that structurally, 39% of all valuable semi-natural grassland habitats in southernSweden are adjacent to public road verges, which in the rural landscape are often considered to be suitable habitat forgrassland species. Additionally, by collecting mud attached to cars and farming machinery and manure from livestock(cattle, horse, sheep) grazing semi-natural grassland pasture, we found that motor vehicles are also capable seed dispers-ers. A similar number of species were dispersed by both vectors, although the composition of samples was quite different.Motor vehicles dispersed more grassland specialists than invasive species, although in much lower abundances than didgrazing livestock. Despite these differences, motor vehicles were found to be able to disperse species with the same kindsof dispersal traits as livestock. A high number of seeds, species and specialists in manure samples means that greater move-ment of livestock is desirable to increase functional grassland connectivity. However, effective management could improvethe suitability of roadsides as grassland corridors and increase the availability of seeds for long-distance human-mediateddispersal via cars and tractors. Our results suggest that in many rural landscapes, connectivity by road networks couldhelp mediate habitat loss and fragmentation of grasslands. However, such effects can be context dependent, and the con-nectivity provided by roads could have serious negative consequences in other regions.

  • 6.
    Bergman, Karl-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Ecology .
    Askling, J
    Ignell, H
    Ekberg, O
    Wahlman, H
    Milberg, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Ecology .
    Landscape effects on butterfly assemblages in an agricultural regio2004In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 27, p. 619-628Article in journal (Refereed)
  • 7.
    Bergman, Karl-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Ecology .
    Kindvall, O.
    Population viability analysis of the butterfly Lopinga achine in a changing landscape in Sweden2004In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 27, no 1, p. 49-58Article in journal (Refereed)
    Abstract [en]

    Metapopulation theory has generally focused only on the stochastic turn-over rate among populations and assumed that the number and location of suitable habitat patches will remain constant through time. This study combines in a PVA both the deterministic landscape dynamics and the stochastic colonisations and extinctions of populations for the butterfly Lopinga achine in Sweden. With data on occupancy pattern and the rate of habitat change, we built a simulation model and examined five different scenarios with different assumptions of landscape changes for L. achine. If no landscape changes would be expected, around 80 populations are predicted to persist during the next 100 yr. Adding the knowledge that many of the sites are unmanaged and that the host plant will slowly deteriorate as canopies close over, and adding environmental variation and synchrony, showed that the number of populations will decrease to around of 4.3 and 2.8 respectively, with an extinction risk of 34% - quite different from the first scenario based only on the metapopulation model. This study has shown the importance of incorporating both deterministic and stochastic events when making a reliable population viability analysis. Even though one can not expect that the long-term predictions of either occupied patches or extinction risks will be accurate quantitatively, the qualitative implications are correct. The extinction risk will be high if grazing is not applied to more patches than is the case today. The simulations indicate that an absolute minimum of 10-30 top-ranked patches needs to be managed for the persistence of the metapopulation of L. achine in the long term. The same problem of abandoned and overgrowing habitats affects many other threatened species in the European landscape and a similar approach could also be applied to them.

  • 8.
    Blanckenhorn, Wolf U.
    et al.
    Univ Zurich, Dept Evolutionary Biol & Environm Studies, Zurich, Switzerland.
    Bauerfeind, Stephanie S.
    Univ Zurich, Dept Evolutionary Biol & Environm Studies, Zurich, Switzerland.
    Berger, David
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology. Univ Zurich, Dept Evolutionary Biol & Environm Studies, Zurich, Switzerland.
    Davidowitz, Goggy
    Univ Arizona, Dept Entomol, Tucson, AZ USA.
    Fox, Charles W.
    Univ Kentucky, Dept Entomol, Lexington, KY USA.
    Guillaume, Frederic
    Univ Zurich, Dept Evolutionary Biol & Environm Studies, Zurich, Switzerland.
    Nakamura, Satoshi
    JIRCAS, Tsukuba, Ibaraki, Japan.
    Nishimura, Kinya
    Hokkaido Univ, Fis Sci, Hakodate, Hokkaido, Japan.
    Sasaki, Hitoshi
    Rakuno Gakuen Univ, Entomol Lab, Ebetsu, Hokkaido, Japan.
    Stillwell, R. Craig
    Univ Arizona, Dept Entomol, Tucson, AZ USA;Univ Kentucky, Dept Entomol, Lexington, KY USA;Univ Lausanne, Dept Ecol & Evolut, Lausanne, Switzerland.
    Tachi, Takuji
    Kyushu Univ, Biosystemat Lab, Fukuoka, Fukuoka, Japan.
    Schaefer, Martin A.
    Univ Zurich, Dept Evolutionary Biol & Environm Studies, Zurich, Switzerland.
    Life history traits, but not body size, vary systematically along latitudinal gradients on three continents in the widespread yellow dung fly2018In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 41, no 12, p. 2080-2091Article in journal (Refereed)
    Abstract [en]

    Large-scale clinal variation in body size and other life-history traits is common enough to have stimulated the postulation of several eco-geographical rules. Whereas some clinal patterns are clearly adaptive, the causes of others remain unclear. We present a comprehensive intraspecific population comparison for the cosmopolitan yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae) to check for consistent world-wide patterns. Common garden assessment of various life history traits permitted continental comparison of (clinal) quantitative genetic differentiation (Qst) with putatively neutral genetic differentiation (Fst) derived from field-caught flies. Latitudinal clines in fly development time, growth rate, and overwintering propensity were consistent among North American, European and Japanese populations. Increased winter dormancy incidence and duration at higher latitude, combined with a faster growth rate and shorter development time, suggest that flies are adaptated to season length more than to temperature. The resulting body size clines, in contrast, were not very consistent; importantly, they were not negative, as expected under seasonal constraints, but flat or even positive clines. Quantitative genetic differentiation Q(ST) exceeded neutral molecular variation F-ST for most traits, suggesting that natural selection plays a consistent role in mediating global dung fly life histories. We conclude that faster growth and development in response to shorter growing seasons at higher latitudes may indirectly counteract expected direct effects of temperature on body-size, potentially resulting in flat or inconsistent body size clines in nature.

  • 9. Brehm, Gunnar
    et al.
    Zeuss, Dirk
    Stockholm University, Faculty of Science, Department of Zoology.
    Colwell, Robert K.
    Moth body size increases with elevation along a complete tropical elevational gradient for two hyperdiverse clades2019In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 42, no 4, p. 632-642Article in journal (Refereed)
    Abstract [en]

    The body size of an animal is probably its most important functional trait. For arthropods, environmental drivers of body size variation are still poorly documented and understood, especially in tropical regions. We use a unique dataset for two species-rich, phylogenetically independent moth taxa (Lepidoptera: Geometridae; Arctiinae), collected along an extensive tropical elevational gradient in Costa Rica, to investigate the correlates and possible causes of body-size variation. We studied 15 047 specimens (794 species) of Geometridae and 4167 specimens (308 species) of Arctiinae to test the following hypotheses: 1) body size increases with decreasing ambient temperature, as predicted by the temperature-size rule; 2) body size increases with increasing rainfall and primary productivity, as predicted from considerations of starvation resistance; and 3) body size scales allometrically with wing area, as elevation increases, such that wing loading (the ratio of body size to wing area) decreases with increasing elevation to compensate for lower air density. To test these hypotheses, we examined forewing length as a proxy for body size in relation to ambient temperature, rainfall, vegetation index and elevation as explanatory variables in linear and polynomial spatial regression models. We analysed our data separately for males and females using two principal approaches: mean forewing length of species at each site, and mean forewing length of complete local assemblages, weighted by abundance. Body size consistently increased with elevation in both taxa, both approaches, both sexes, and also within species. Temperature was the best predictor for this pattern (-0.98 < r < -0.74), whereas body size was uncorrelated or weakly correlated with rainfall and enhanced vegetation index. Wing loading increased with elevation. Our results support the temperature-size rule as an important mechanism for body size variation in arthropods along tropical elevational gradients, whereas starvation resistance and optimization of flight mechanics seem to be of minor importance.

  • 10. Brown, Carissa D.
    et al.
    Dufour-Tremblay, Geneviève
    Jameson, Ryan G.
    Mamet, Steven D.
    Trant, Andrew J.
    Walker, Xanthe J.
    Boudreau, Stéphane
    Harper, Karen A.
    Henry, Gregory H. R.
    Hermanutz, Luise
    Hofgaard, Annika
    Isaeva, Ludmila
    Kershaw, G. Peter
    Johnstone, Jill F.
    Reproduction as a bottleneck to treeline advance across the circumarctic forest tundra ecotone2019In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 42, no 1, p. 137-147Article in journal (Refereed)
    Abstract [en]

    The fundamental niche of many species is shifting with climate change, especially in sub-arctic ecosystems with pronounced recent warming. Ongoing warming in sub-arctic regions should lessen environmental constraints on tree growth and reproduction, leading to increased success of trees colonising tundra. Nevertheless, variable responses of treeline ecotones have been documented in association with warming temperatures. One explanation for time lags between increasingly favourable environmental conditions and treeline ecotone movement is reproductive limitations caused by low seed availability. Our objective was to assess the reproductive constraints of the dominant tree species at the treeline ecotone in the circumpolar north. We sampled reproductive structures of trees (cones and catkins) and stand attributes across circumarctic treeline ecotones. We used generalized linear mixed models to estimate the sensitivity of seed production and the availability of viable seed to regional climate, stand structure, and species-specific characteristics. Both seed production and viability of available seed were strongly driven by specific, sequential seasonal climatic conditions, but in different ways. Seed production was greatest when growing seasons with more growing degree days coincided with years with high precipitation. Two consecutive years with more growing degree days and low precipitation resulted in low seed production. Seasonal climate effects on the viability of available seed depended on the physical characteristics of the reproductive structures. Large-coned and -seeded species take more time to develop mature embryos and were therefore more sensitive to increases in growing degree days in the year of flowering and embryo development. Our findings suggest that both moisture stress and abbreviated growing seasons can have a notable negative influence on the production and viability of available seed at treeline. Our synthesis revealed that constraints on predispersal reproduction within the treeline ecotone might create a considerable time lag for range expansion of tree populations into tundra ecosystems.

  • 11. Bruun, Hans Henrik
    et al.
    Österdahl, Sofia
    Moen, Jon
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Distinct patterns in alpine vegetation around dens of the Arctic fox2005In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 28, no 1, p. 81-87Article in journal (Refereed)
    Abstract [en]

    The arctic fox Alopex lugopus excavates its dens in gravely ridges and hillocks, and creates a local environment quite distinct from the surrounding tundra or heath landscape. In northern Sweden, the vegetation of 18 dens of the arctic fox was investigated, as well as reference areas off the dens but in geologically and topographically similar locations. The species composition showed considerable differences between den and reference areas, with grasses and forbs occurring more abundantly on the dens, and evergreen dwarf-shrubs occurring more in reference areas. The effect of the foxes' activities is thought to be either through mechanical soil disturbance, or through nutrient enrichment via scats, urine, and carcasses. This was expected to result in differences in plant traits with key functional roles in resource acquisition and regeneration, when comparing dens with reference areas. We hypothesised that the community mean of specific leaf area (SLA) would differ if nutrient enrichment was the more important effect, and that seed weight, inversely proportional to seed number per ramet and hence dispersal ability, would differ if soil disturbance was the more important effect. Specific leaf area showed a significant difference, indicating nutrient enrichment to be the most important effect of the arctic fox on the vegetation on its dens. Arctic foxes act as ecosystems engineers on a small scale, maintaining niches for relatively short-lived nutrient demanding species on their dens in spite of the dominance of long-lived ericaceous dwarf-shrubs in the landscape matrix. Thus, foxes contribute to the maintenance of species richness on the landscape level.

  • 12.
    Carvalheiro, Luisa G.
    et al.
    Univ Fed Goias, Brazil;Univ Lisbon, Portugal.
    Biesmeijer, Jacobus C.
    Naturalis Biodivers Ctr, Netherlands;Leiden Univ, Netherlands.
    Franzén, Markus
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. UFZ Ctr Environm Res, Germany.
    Aguirre-Gutierrez, Jesus
    Naturalis Biodivers Ctr, Netherlands;Univ Oxford, UK.
    Garibaldi, Lucas A.
    Universidad Nacional de Río Negro, Argentina;Consejo Nacl Invest Cient & Tecn CONICET, Argentina.
    Helm, Aveliina
    Univ Tartu, Estonia.
    Michez, Denis
    Univ Mons, Belgium.
    Poyry, Juha
    Finnish Environm Inst SYKE, Finland.
    Reemer, Menno
    Naturalis Biodivers Ctr, Netherlands;European Invertebrate Survey Netherlands, Netherlands.
    Schweiger, Oliver
    UFZ Ctr Environm Res, Germany.
    van den Berg, Leon
    Bosgrp Zuid Nederland, Netherlands;Radboud Univ Nijmegen, Netherlands.
    WallisDeVries, Michiel F.
    De Vlinderstichting Dutch Butterfly Conservat, Netherlands;Wageningen Univ, Netherlands.
    Kunin, William E.
    Univ Leeds, UK.
    Soil eutrophication shaped the composition of pollinator assemblages during the past century2019In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587Article in journal (Refereed)
    Abstract [en]

    Atmospheric nitrogen deposition and other sources of environmental eutrophication have increased substantially over the past century worldwide, notwithstanding the recent declining trends in Europe. Despite the recognized susceptibility of plants to eutrophication, few studies evaluated how impacts propagate to consumers, such as pollinators. Here we aim to test if soil eutrophication contributes to the temporal dynamics of pollinators and their larval resources. We used a temporally and spatially explicit historical dataset with information on species occurrences to test if soil eutrophication, and more specifically nitrogen deposition, contributes to the patterns of change of plant and pollinator richness in the Netherlands over an 80 yr period. We focus on bees and butterflies, two groups for which we have good knowledge of larval resources that allowed us to define groups of species with different nitrogen related diet preferences. For each group we estimated richness changes between different 20-yr periods at local, regional and national scale, using analytical methods developed for analyzing richness changes based on collection data. Our findings suggest that the impacts of soil eutrophication on plant communities propagate to higher trophic levels, but with a time-lag. Pollinators with nitrogen-related diet preferences were particularly affected, in turn potentially impairing the performance of pollinator-dependent plants. Pollinator declines continued even after their focal plants started to recover. In addition, our results suggest that current levels of nitrogen deposition still have a negative impact on most groups here analyzed, constraining richness recoveries and accentuating declines. Our results indicate that the global increase in nitrogen availability plays an important role in the ongoing pollinator decline. Consequently, species tolerances to soil nitrogen levels should be considered across all trophic levels in management plans that aim to halt biodiversity loss and enhance ecosystems services worldwide.

  • 13.
    Cassel-Lundhagen, Anna
    et al.
    SLU, Uppsala.
    Tammaru, Toomas
    Tartu University, Estland.
    Windig, Jack J
    Wageningen University, Nederländerna.
    Ryrholm, Nils
    Högskolan i Gävle.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Are peripheral populations special? Congruent patterns in two butterfly species2009In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, no 4, p. 591-600Article in journal (Refereed)
    Abstract [en]

    Populations at range margins may be genetically different from more central ones for a number of mutually non-exclusive reasons. Specific selection pressures may operate in environments that are more marginal for the species. Genetic drift may also have a strong effect in these populations if they are small, isolated and/or have experienced significant bottlenecks during the colonisation phase. The question if peripheral populations are special, and if yes then how and why, is of obvious relevance for speciation theory, as well as for conservation biology. To evaluate the uniqueness of populations at range margins and the influence of gene flow and selection, we performed a morphometric study of two grassland butterfly species: Coenonympha arcania and C. hero (Lepidoptera: Nymphalidae). The samples were collected from Swedish populations that are peripheral and isolated from the main area of the species distributions and from populations in the Baltic states that are peripheral but connected to the main area of the species distributions. These samples were compared to those from central parts of the species distributions. The isolated populations in both species differed consistently from both peripheral and central populations in their wing size and shape. We interpret this as a result of selection caused by differences in population structure in these isolated locations, presumably favoring different dispersal propensity of these butterflies. Alternative explanations based on colonisation history, latitudinal effects, inbreeding or phenotypic plasticity appear less plausible. As a contrast, the much weaker and seemingly random among-region differences in wing patterns are more likely to be ascribed to weaker selection pressures allowing genetic drift to be influential. In conclusion, both morphological data and results from neutral genetic markers in earlier studies of the same system provide congruent evidence of both adaptation and genetic drift in the isolated Swedish populations of both species.

  • 14.
    Cassel-Lundhagen, Anna
    et al.
    Swedish University of Agricultural Sciences, Dept of Ecology, Uppsala, Sweden.
    Tammaru, Toomas
    Institute of Ecology, and Earth Sciences, University of Tartu, Tartu, Estonia.
    Windig, Jack
    Animal Breeding and Genomics Centre, Animal Sciences Group, Wageningen UR, Lelystad, Netherlands.
    Ryrholm, Nils
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för naturvetenskap.
    Nylin, Sören
    Department of Zoology, Stockholm University, Stockholm, Sweden.
    Are peripheral populations special? Congruent patterns in two butterfly species2009In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, no 4, p. 591-600Article in journal (Refereed)
    Abstract [en]

    Populations at range margins may be genetically different from more central ones for a number of mutually non-exclusive reasons. Specific selection pressures may operate in environments that are more marginal for the species. Genetic drift may also have a strong effect in these populations if they are small, isolated and/or have experienced significant bottlenecks during the colonisation phase. The question if peripheral populations are special, and if yes then how and why, is of obvious relevance for speciation theory, as well as for conservation biology. To evaluate the uniqueness of populations at range margins and the influence of gene flow and selection, we performed a morphometric study of two grassland butterfly species: from Swedish populations that are peripheral and isolated from the main area of the species distributions and from populations in the Baltic states that are peripheral but connected to the main area of the species distributions. These samples were compared to those from central parts of the species distributions. The isolated populations in both species differed consistently from both peripheral and central populations in their wing size and shape. We interpret this as a result of selection caused by differences in population structure in these isolated locations, presumably favoring different dispersal propensity of these butterflies. Alternative explanations based on colonisation history, latitudinal effects, inbreeding or phenotypic plasticity appear less plausible. As a contrast, the much weaker and seemingly random amongregion differences in wing patterns are more likely to be ascribed to weaker selection pressures allowing genetic drift to be influential. In conclusion, both morphological data and results from neutral genetic markers in earlier studies of the same system provide congruent evidence of both adaptation and genetic drift in the isolated Swedish populations of both species.

     

  • 15. De Frenne, Pieter
    et al.
    Graae, Bente J.
    Kolb, Annette
    Shevtsova, Anna
    Baeten, Lander
    Brunet, Jorg
    Chabrerie, Olivier
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Decocq, Guillaume
    Dhondt, Rob
    Diekmann, Martin
    Gruwez, Robert
    Heinken, Thilo
    Hermy, Martin
    Oster, Mathias
    Saguez, Robert
    Stanton, Sharon
    Tack, Wesley
    Vanhellemont, Margot
    Verheyen, Kris
    An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient2011In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, no 1, p. 132-140Article in journal (Refereed)
    Abstract [en]

    We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.

  • 16. De Frenne, Pieter
    et al.
    Graae, Bente J
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kolb, Annette
    Shevtsova, Anna
    Baeten, Lander
    Brunet, Jörg
    Chabrerie, Olivier
    Cousins, Sara A O
    Decocq, Guillaume
    Dhondt, Rob
    Diekmann, Martin
    Gruwez, Robert
    Heinken, Thilo
    Hermy, Martin
    Öster, Mathias
    Saguez, Robert
    Stanton, Sharon
    Tack, Wesley
    Vanhellemont, Margot
    Verheyen, Kris
    An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient2011In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, no 1, p. 132-140Article in journal (Refereed)
    Abstract [en]

    We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.

  • 17. De Frenne, Pieter
    et al.
    Graae, Bente J.
    Kolb, Annette
    Shevtsova, Anna
    Baeten, Lander
    Brunet, Jörg
    Chabrerie, Olivier
    Cousins, Sara A. O.
    Decocq, Guillaume
    Dhondt, Rob
    Diekmann, Martin
    Gruwez, Robert
    Heinken, Thilo
    Hermy, Martin
    ֖ster, Mathias
    Saguez, Robert
    Stanton, Sharon
    Tack, Wesley
    Vanhellemont, Margot
    Verheyen, Kris
    An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient2011In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, no 1, p. 132-140Article in journal (Refereed)
    Abstract [en]

    We applied the leaf-height-seed (LHS) ecology strategy scheme (a combination of three ecologically important traits: specific leaf area (SLA), seed mass and plant height) intraspecifically to two widespread European forest herbs along a latitudinal gradient. The aims of this study were to quantify LHS trait variation, disentangle the environmental factors affecting these traits and compare the within-species LHS trait relationships with latitude to previously established cross-species comparisons. We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-€“2300 €…km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.

  • 18.
    Dettki, Holger
    et al.
    Umeå Universitet.
    Edman, Mattias
    Umeå Universitet.
    Esseen, Per-Anders
    Umeå Universitet.
    Hedenås, Henrik
    Umeå Universitet.
    Jonsson, Bengt Gunnar
    Umeå Universitet.
    Kruys, Nic
    Umeå Universitet.
    Moen, Jon
    Umeå Universitet.
    Renhorn, Karl Erik
    Umeå Universitet.
    Screening for species potentially sensitive to habitat fragmentation1998In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 21, no 6, p. 649-652Article in journal (Refereed)
  • 19. Dokter, Adriaan M.
    et al.
    Desmet, Peter
    Spaaks, Jurriaan H.
    van Hoey, Stijn
    Veen, Lourens
    Verlinden,, Liesbeth
    Nilsson, Cecilia
    Haase, Günther
    SMHI, Research Department, Atmospheric remote sensing.
    Leijnse, Hidde
    Farnsworth,, Andrew
    Bouten, Willem
    Shamoun-Baranes, Judy
    bioRad: biological analysis and visualization of weather radar data2018In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, no 42, p. 1-9Article in journal (Refereed)
  • 20. Dokter, Adriaan M.
    et al.
    Desmet, Peter
    Spaaks, Jurriaan H.
    van Hoey, Stijn
    Veen, Lourens
    Verlinden, Liesbeth
    Nilsson, Cecilia
    Haase, Günther
    SMHI, Research Department, Atmospheric remote sensing.
    Leijnse, Hidde
    Farnsworth, Andrew
    Bouten, Willem
    Shamoun-Baranes, Judy
    bioRad: biological analysis and visualization of weather radar data2019In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 42, no 5, p. 852-860Article in journal (Refereed)
  • 21. Dunn, RM
    et al.
    Colwell, RK
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The river domain: why are there more species halfway up the river?2006In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 29, no 2, p. 251-259Article in journal (Refereed)
  • 22.
    Edman, Mattias
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gustafsson, Mårten
    Stenlid, Jan
    Jonsson, Bengt Gunnar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ericson, Lars
    Spore deposition of wood-decaying fungi: Importance of landscape composition2004In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 27, no 1, p. 103-111Article in journal (Refereed)
  • 23.
    Eggertsen, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Goodell, Whitney
    Cordeiro, César
    Cossa, Damboia
    Bouças, Marcos
    Berkström, Charlotte
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Franco, João
    Ferreira, Carlos Eduardo
    Bandeira, Salomão
    Gullström, Martin
    Where is the grass greenest? Influence of seascape structure and marine protected areas on fish distribution patterns in a seagrass-dominated landscapeIn: Ecography, ISSN 0906-7590, E-ISSN 1600-0587Article in journal (Refereed)
    Abstract [en]

    Tropical seagrass beds are critical habitats for many resident- and nursery fish species. While numerous studies have explored factors that structure reef fish assemblages, few have investigated the relative influence of multiple factors at fine- and large spatial scales as well as MPAs on seagrass fish. To understand which are the most important factors structuring fish assemblages in tropical seagrass beds, and how this is related to life history of species, we investigated fish distribution patterns at 20 sites in 13 different seagrass beds across the Bazaruto Archipelago, Mozambique. Using boosted regression tree modelling, we assessed the influence of fine-scale variables (seagrass meadow characteristics) and seascape variables (distance to adjacent habitats) on abundance of four nursery taxa (Lutjanus fulviflamma, Lethrinus spp., Scarus ghobban and Gerres spp.) and two resident species (Pelates quadrilineatus and Leptoscarus vaigiensis). We found that seascape variables were generally more important than seagrass characteristics, and that the influence of different variables was highly taxon-specific. Fish distribution patterns in seagrass-dominated seascapes were related to life history traits of the species; nursery fish taxa were negatively correlated with distance to adult habitats, while resident species occurred in higher abundances far from reefs. Proximity to mangroves was important for taxa that utilised mangroves in addition to seagrass as nurseries. Most seascape variables influenced fish abundances on a large spatial scale (km). The influence of protected areas was taxon-specific, with stronger effects on resident species than on nursery species, with geographical placement shadowing potential effects of protection on fish abundance. Our results indicate that protection efforts in seagrass-dominated seascapes can have varying impacts on fish distribution, depending on the geographical location of the reserve. This highlights the importance of considering seascape arrangement and the ecology of targeted species for conservation and marine spatial planning in seagrass-dominated systems.

  • 24.
    Elmberg, Johan
    et al.
    Deptartment of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Deptartment of Applied Zoology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Evo Game Research Station.
    Sjöberg, Kjell
    Deptartment of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Factors affecting species number and density of dabbling duck guilds in North Europe1993In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 16, no 3, p. 251-260Article in journal (Refereed)
    Abstract [en]

    We addressed how species number and pair density in guilds of co-existing species is related to habitat structure, and to the abundance and diversity of food resources. using the assemblage of seven species of dabbling ducks (genus Anas) breeding in 60 lakes distributed over six regions in temperate north Europe. Partial correlation and multiple regression revealed that species richness was best predicted by habitat structural diversity as indexed by a principal component analysis based on 18 vegetation and lake characteristics, and by the abundance of aquatic and emergent prey. We found no effect of lake size or prey size diversity on species richness. Pair density was correlated with the percentage of shoreline with horsetails (Equisetum), by habitat structural diversity and by the abundance of emergent invertebrate prey. Neither prey size diversity nor abundance of aquatic prey correlated with pair density. Species richness and pair density in North European duck guilds vary both with habitat structure and prey availability.

  • 25. Emerson, Brent C.
    et al.
    Kolm, Niclas
    Uppsala universitet, Zooekologi.
    Response to comments on Species diversity can drive speciation2007In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 30, no 3, p. 334-338Article in journal (Refereed)
  • 26. Emerson, Brent C.
    et al.
    Kolm, Niclas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Response to comments on Species diversity can drive speciation2007In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 30, no 3, p. 334-338Article in journal (Refereed)
  • 27.
    Eriksen, B
    et al.
    University of Gothenburg.
    Molau, U
    University of Gothenburg.
    Svensson, Mikael
    University of Gothenburg.
    Reproductive strategies in two arctic Pedicularis species (Scrophulariaceae)1993In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 16, no 2, p. 154-166Article in journal (Refereed)
    Abstract [en]

    A study of a number of reproductive traits in two sympatric species of Pedicularis in northern Swedish Lapland, the subarctic-alpine P lapponica and the artic P hursuta, revealed that the life-history strategies of the two species differ profoundly High fruit set and low seed abortion rate, as m P hursuta, is common in arctic plants in late-thawing habitats and represents a case of extreme adversity selection rather than an indication of a ruderal life-history strategy Pedicularis lapponica, on the other hand, is a typical K-strategist (or stress-tolerator) requiring a longer period of growth for optimal reproduction Occuring at both low and high altitudes in the area, P lapponica tends to increase in self-compatibility with altitude, which is interpreted as an adaptation to lower pollinator visitation frequency in arctic environments The variation in length of the protruding part of the style in P lapponica is shown to be correlated with exposure to light Predispersal seed predation is severe m P lapponica at low altitudes, where the capsules are attacked by fly and moth larvae At high altitudes, a minor proportion of the capsules of P lapponica experience predation and only from flies, while P hursuta is completely unpredated

  • 28.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Species pools in cultural landscapes - niche construction, ecological opportunity and niche shifts2013In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, no 4, p. 403-413Article, review/survey (Refereed)
    Abstract [en]

    This paper discusses the ecology of species that were favoured by the development of the cultural landscape in central and NW Europe beginning in the Neolithic and the Bronze Age, with a focus on mechanisms behind species responses to this landscape transformation. A fraction of species may have maintained their realized niches from the pre- agricultural landscape and utilized similar niches created by the landscape transformation. However, I suggest that many species responded by altering their niche relationships, and a conceptual model is proposed for this response, based on niche construction, ecological opportunity and niche shifts. Human-mediated niche construction, associated with clearing of forests and creation of pastures and fields promoted niche shifts towards open habitats, and species exploited the ecological opportunity provided by these created environments. This process was initially purely ecological, i.e. the new habitats must have been included in the original fundamental niche of the species. Two other features of human-mediated niche construction, increased interconnectivity and increased spatial stability of open habitats, resulted in species accumulating in the habitats of the constructed landscape. As a consequence, selection processes were initiated favouring traits promoting fitness in the constructed landscape. This process implied a feed-back to niche shifts, but now also including evolutionary changes in fundamental niches. I briefly discuss whether this model can be applied also to present-day anthropogenic impact on landscapes. A general conclusion is that ecological and evolutionary changes in species niches should be more explicitly considered in modeling and predictions of species response to present-day landscape and land-use changes.

  • 29.
    Forsman, Anders
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Wennersten, Lena
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Inter-individual variation promotes ecological success of populations and species: evidence from experimental and comparative studies2016In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 39, no 7, p. 630-648Article, review/survey (Refereed)
    Abstract [en]

    Biological diversity is threatened by exploitation, fragmentation of natural habitats, pollution, climatechange, and anthropogenic spread of species. The question of how among-individual variation influencesthe performance of populations and species is a poorly explored but currently growing field of research.Here, we review 31 experimental and 14 comparative studies and first investigate whether there is empiricalsupport for the propositions that higher levels of among-individual phenotypic and genetic variationpromote the ecological and evolutionary success of populations and species in the face of environmentalchange. Next, we examine whether and how the effect of diversity depends on environmental conditions.Finally, we explore whether the relationship linking population fitness to diversity is typically linear,asymptotic, or whether the benefits peak at intermediate diversity. The reviewed studies provide strong,almost invariable, evidence that more variable populations are less vulnerable to environmental changes,show decreased fluctuations in population size, have superior establishment success, larger distributionranges, and are less extinction prone, compared with less variable populations or species. Given theoverwhelming evidence that variation promotes population performance, it is important to identifyconditions when increased variation does not have the theoretically expected effect, a question ofconsiderable importance in biodiversity management, where there are many other practical constraints. Wefind that experimental outcomes generally support the notion that genetic and phenotypic variation is ofgreater importance under more stressful than under benign conditions. Finally, population performanceincreased linearly with increasing diversity in the majority (10 of 12) of manipulation studies that includedfour or more diversity levels; only two experiments detected curvilinear relationships.

  • 30.
    Forsman, Jukka T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Hjernquist, Mårten B.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Gustafsson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Experimental evidence for the use of density based interspecific social information in forest birds2009In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, no 3, p. 539-545Article in journal (Refereed)
    Abstract [en]

    Reproductive success and habitat preference are generally assumed to be negatively associated with densities of con- and heterospecific competitors. However, recent theoretical studies have suggested that in some cases habitat preference may have a nonlinear unimodal function in relation to con- or heterospecific competitor densities - intermediate densities being preferred. Such a pattern is expected if con- or heterospecific densities are used as a proximate cue in habitat selection, which may produce benefits by reducing searching costs and providing information about current habitat quality and costs of competition. At low density the use of such cues, and hence habitat selection, are hampered, whereas at high density costs of competition exceed the benefits of using cues, leading to avoidance. Here, we tested this hypothesis by examining whether arboreal migratory birds use the density of resident titmice (Parus spp.) in habitat selection decisions. Many migrants and titmice species share similar resource needs making titmice density a reliable source of information for migrants. At the scale of habitat patches, we experimentally created a range of titmice densities from low to very high and subsequently measured the density response of migrants. In contrast to the unimodal habitat preference hypothesis, the average species number and total density of migratory birds were positively and linearly correlated with manipulated titmice density. Thus, migrants probably use titmice density as a relative indicator of habitat quality (abundance or quality of food) because foliage gleaners that share similar food resource with titmice, but not ground foragers, showed a positive association with manipulated titmice density. These results emphasize the positive effect of interspecific social information on habitat choice decisions and diversity of migratory bird community.

  • 31. Gibbs, Melanie
    et al.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Van Dyck, Hans
    Temperature, rainfall and butterfly morphology: does life history theory match the observed pattern?2011In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, no 2, p. 336-344Article in journal (Refereed)
    Abstract [en]

    Butterfly distribution and abundance is known to be influenced by temperature and rainfall. What is not clear, however, is how life history and flight morphological traits are affected by changes in local weather conditions. During the period 1989-1999, we explored the effects of ambient temperature and rainfall during larval development on adult phenotypic traits (body mass, forewing loading, forewing surface area and forewing length) in a Swedish population of the speckled wood butterfly Pararge aegeria. As different seasonal cohorts correspond to different developmental pathways (larval hibernating, pupal hibernating and directly developing), we analysed these morphological time series relative to developmental pathway. Phenotypic variation in response to the temperature and rainfall levels experienced during larval development differed in both magnitude and direction depending on the developmental pathway, and hence seasonal cohort, examined (i.e. there was a pathway-specific response). We suggest that through its developmental flexibility P. aegeria may be able to adjust to variation in weather conditions over time. Other less flexible species, however, may not be so fortunately buffered. To truly estimate the impact of climate change on biodiversity more fine-scale, local studies are required that examine the mechanisms underlying the response of species to climate change.

  • 32.
    Granath, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Vicari, M.
    Bazely, Dawn R.
    Ball, John P.
    Puentes, Adriana
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Rakocevic, T.
    Variation in the abundance of fungal endophytes in fescue grasses along altitudinal and grazing gradients2007In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 30, no 3, p. 422-430Article in journal (Refereed)
    Abstract [en]

    Epichloë festucae, a common fungal symbiont of the genus Festuca (family Poaceae), can provide its host plant with protection against herbivores. However, infection might also be associated with a cost to its host plant. We examined the distribution of Epichloë festucae infection in natural populations of three fescue grasses, Festuca rubra, F. ovina and F. vivipara, on mountains in northern Sweden to determine whether infection frequency varied with reindeer Rangifertarandus grazing pressure and altitude. Two differently-scaled approaches were used: 1) infection frequency was measured at a local scale along ten elevational transects within a ca 400 km2 area and 2) infection frequency was measured on a regional scale along elevational transects on 17 mountains classified as having a history of high or low reindeer grazing pressure. Mean infection frequencies in F. rubra were 10% (vegetative tillers at a local scale), and 23% (flowering culms at a regional scale), and in F. ovina they were 13% (local scale) and 15% (regional scale). Endophyte infection frequency in F. vivipara, was, on average, 12% (local scale) and 37% (regional scale). In F. rubra, infection decreased significantly with increasing altitude at both the local and regional scale, and was positively correlated with grazing pressure. In F. ovina, an opposite trend was found at the regional scale: infection frequency increased significantly with increasing altitude, while no discernible distribution pattern was observed at the local scale. No elevational trends were observed in infection of F. vivipara. These patterns in the distribution of endophyte-infected grasses in non-agricultural ecosystems may be explained by both biotic (grazing) and abiotic factors (altitude). Differences in ecology and life history of the studied grass species may also be of importance for the different results observed among species.

  • 33.
    Gunnarsson, Urban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Malmer, N.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Dynamics or constancy in Sphagnum dominated mire ecosystems? A 40-year study2002In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 25, no 6, p. 685-704Article in journal (Refereed)
    Abstract [en]

    Traditionally mire ecosystems (especially bogs) have been viewed as stable systems with slow changes in the vegetation over time. In this study the mire Akhultmyren, south-central Swedenw as re-investigatedin 1997 after 40 yr of continued natural development. The results show a high degree of dynamics in a Sphagnum dominated bog and fen. Altogether 97 vascular plant and bryophyte species were recorded in the two inventories of the bog and poor fen vegetation ,p H and electrical conductivity in the mire water were also surveyed. In 1997 we found 10 new species and that 8 species had disappeared since 1954 but the over-all mean number of species per plot (size 400 m2) had hardly changed. However, 21% of the species increased and 21% decreased significantly in frequency. Most of the species that decreased in frequency were low-grown vascular plants, most common in wet microhabitats. Vascular plant species that increased in frequency included trees (defined as > 1.3 m in height) and were generally taller than the unchanged or decreasing species. The frequency of dwarf shrubs and hummock bryophytes increased too. Areas with an initial pH of 4.5-5.0 showed the strongest decrease in pH, coinciding with an enlarged distribution of some Sphagnum species. The species diversity increased on the bog, but decreased in the wettest parts of the fen, where the pH also decreased. Species with unchanged or increasing frequency often showed high capacity to colonise new plots. On average the sum of gains and losses of species in the plots in 1997 was ca 50% of the species number in 1954. The vegetation changes indicate a drier mire surface and anincreaseda vailability of nitrogen. The increased tree cover may have triggered further changes in the plant cover.

  • 34.
    Hambäck, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, K-O
    Bommarco, R
    Krauss, J
    Kuussarri, M
    Pöyry, J
    Öckinger, E
    Allometric density responses in butterflies: The response to small and large patches by small and large species.2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, p. 1149-1156Article in journal (Refereed)
  • 35.
    Hambäck, Peter
    et al.
    Department of Botany, Stockholm University.
    Karl-Olof, Bergman
    Linköping University, Department of Physics, Chemistry and Biology, Ecology . Linköping University, The Institute of Technology.
    Bommarco, Riccardo
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala.
    Krauss, Jochen
    Population Ecology Group, Department of Animal Ecology I, University of Bayeruth, Germany.
    Kuussaari, Mikko
    Finnish Environment Inst. Research Programme for Biodiversity, Helsinki, Finland.
    Pöyry, Juha
    Finnish Environment Inst. Research Programme for Biodiversity, Helsinki, Finland.
    Öckinger, Erik
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala.
    Allometric density responses in butterflies: the response to small and large patches by small and large species2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, no 6, p. 1149-1156Article in journal (Refereed)
    Abstract [en]

    Species are differentially affected by habitat fragmentation as a consequence of differences in mobility, area requirements, use of the matrix, and responses to edges. A quantitative understanding of these differences is essential not only for conservation biology but also for basic ecological theory. Here, we examine density responses by butterflies to patch size and use a quantitative theory on the scaling of population density with patch size to interpret results. Theory suggests that the density distribution of mobile species along a patch size gradient should depend on the scaling of net migration rates, whereas the density distribution of less mobile species should depend more on local growth. Using data from 11 localities in three European countries, we calculated the slope in the relationship between patch size and population density. These slopes were evaluated in relation to butterfly traits and matrix composition. As estimates of butterfly mobility we used both wing span and expert mobility rankings. The slope of the density–area relationship changed as predicted with wing span and the association of species to grasslands. Large and highly mobile species had a negative slope, similarly for grassland specialists and generalist species, and the slope matched quantitative predictions based on the scaling of net migration rates. Small and less mobile grassland specialists had a slope that was less negative than the slope of large and mobile grassland specialists, whereas the slope did not change with size for generalist species. These analyses suggest that the variability in response among butterfly species to patch size could be explained by accounting for body size/mobility and habitat associations among species. A caveat is that edge effects are not explicitly included in the model analysis, and future research should aim to combine area and edge effects in a common theoretical framework.

  • 36. Herfindal, Ivar
    et al.
    Linnell, John D. C.
    Elmhagen, Bodil
    Andersen, Roy
    Eide, Nina E.
    Frafjord, Karl
    Henttonen, Heikki
    Kaikusalo, Asko
    Mela, Matti
    Tannerfeldt, Magnus
    Dalen, Love
    Strand, Olav
    Landa, Arild
    Angerbjorn, Anders
    Population persistence in a landscape context: the case of endangered arctic fox populations in Fennoscandia2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, no 5, p. 932-941Article in journal (Refereed)
  • 37.
    Herfindal, Ivar
    et al.
    Norwegian University of Science and Technology.
    Linnell, John D. C.
    Norwegian Institute for Nature Research.
    Elmhagen, Bodil
    Stockholm University, Faculty of Science, Department of Zoology.
    Andersen, Roy
    Norwegian Institute for Nature Research.
    Eide, Nina E
    Norwegian Institute for Nature Research.
    Frafjord, Karl
    Tromsö University.
    Henttonen, Heikki
    Metla - Finnish Forest Research Institute.
    Kaikusalo, Asko
    Metla - Finnish Forest Research Institute.
    Mela, Matti
    Metsähallitus - Finnish Park and Forestry Service.
    Tannerfeldt, Magnus
    Swedish Polar Research Secretariat.
    Dalén, Love
    Swedish Museum of Natural History.
    Strand, Olav
    Norwegian Institute for Nature Research.
    Landa, Arild
    Norwegian Institute for Nature Research.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Population persistence in a landscape context: the case of endangered arctic fox populations in Fennoscandia2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, no 5, p. 932-941Article in journal (Refereed)
    Abstract [en]

    Anthropogenic fragmentation of habitat and populations is recognized as one of the most important factors influencing loss of biodiversity. Since it is difficult to quantify demographic parameters in small populations, we need alternative methods to elucidate important factors affecting the viability of local populations. The Fennoscandian arctic fox inhabits a naturally fragmented alpine tundra environment, but historic anthropogenic impacts have further fragmented its distribution. After almost 80 yr of protection, the population remains critically endangered. Both intrinsic factors (related to the isolation and size of sub-populations) and extrinsic factors (related to environmental conditions influencing patch quality and interspecific competition) have been proposed as explanations for the lack of population growth. To distinguish between these hypotheses, we conducted a spatially explicit analysis that compares areas where the species has persisted with areas where it has become locally extinct. We used characteristics of the fragments of alpine tundra habitat and individual arctic fox breeding dens (including both currently active dens and historically active dens) within the fragments to evaluate the importance of habitat characteristics and connectivity in explaining variation in persistence within a fragment. The number of reproductive events in a fragment was related to the size of the fragment, but not more than expected following a 1:1 relationship, suggesting little effect of fragment size on the relative number of reproductions. The likelihood of a den being used for breeding was positively associated with factors minimising interspecific competition as well as increasing within-fragment connectivity. These results support the idea that the failure of Fennoscandian arctic fox to recover is caused by demographic factors that can be related to fine-scale Allee or Allee-like effects, as well as environmental influences related to increased competition and exclusion by red foxes

  • 38.
    Hjalmarsson, Anna
    et al.
    Swedish Museum of Natural History, Department of Zoology.
    Bergsten, Johannes
    Swedish Museum of Natural History, Department of Zoology.
    Monaghan, Michael
    Dispersal is linked to habitat use in 59 species of water beetles (Coleoptera: Adephaga) on Madagascar2014In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 37, p. 001-008Article in journal (Refereed)
    Abstract [en]

    Lentic habitats (standing water, such as ponds and lakes) differ from lotic habitats (running water; streams and rivers) in their spatiotemporal persistence, with lentic habitats being more ephemeral in evolutionary time. This habitat instability is thought to select for dispersal, and several phylogenetic and macroecological studies have suggested that high rates of dispersal are more characteristic of lentic than lotic species. We tested this hypothesis using a comparative population genetic and phylogeographic approach based on mitochondrial DNA for 59 aquatic beetle species, sampled across Madagascar. Species were classified as lotic (n = 25), lentic (n = 25), or lotolentic (associated with both running and standing water; n = 9). Hierarchical population genetic structure (AMOVA), nucleotide diversity (π), and geographic structure were compared among habitat types. Lotic species had significantly greater population structure (ФST = 0.55, hierarchical AMOVA) than lentic (ФST = 0.13) and lotolentic (ФST = 0.19) species using phylogenetic generalized least squares (PGLS) to correct for phylogeny. Body size was independent of habitat preference, and did not explain any of the intraspecific variation. A greater proportion of lotic species were endemic to Madagascar and lotic species had more pronounced geographic structure in their haplotype networks. The results indicate that dispersal is consistently lower among lotic species, independent of phylogenetic relatedness. This has macroevolutionary and biogeographical consequences for the freshwater fauna of this tropical biodiversity hotspot where remaining natural habitats are becoming increasingly isolated from one another.

  • 39. Hoset, Katrine S.
    et al.
    Kyro, Kukka
    Oksanen, Tarja
    Oksanen, Lauri
    Olofsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Spatial variation in vegetation damage relative to primary productivity, small rodent abundance and predation2014In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 37, no 9, p. 894-901Article in journal (Refereed)
    Abstract [en]

    The relative importance of top-down and bottom-up mechanisms in shaping community structure is still a highly controversial topic in ecology. Predatory top-down control of herbivores is thought to relax herbivore impact on the vegetation through trophic cascades. However, trophic cascades may be weak in terrestrial systems as the complexity of food webs makes responses harder to predict. Alternatively, top-down control prevails, but the top-level (predator or herbivore) changes according to productivity levels. Here we show how spatial variation in the occurrence of herbivores (lemmings and voles) and their predators (mustelids and foxes) relates with grazing damage in landscapes with different net primary productivity, generating two and three trophic level communities, during the 2007 rodent peak in northern Norway. Lemmings were most abundant on the unproductive high-altitude tundra, where few predators were present and the impact of herbivores on vegetation was strong. Voles were most common on a productive, south facing slope, where numerous predators were present, and the impacts of herbivores on vegetation were weak. The impact of herbivores on the vegetation was strong only when predators were not present, and this cannot be explained by between-habitat differences in the abundance of plant functional groups. We thus conclude that predators influence the plant community via a trophic cascade in a spatial pattern that support the exploitation ecosystems hypothesis. The responses to grazing also differed between plant functional groups, with implications for short and long-term consequences for plant communities.

  • 40. Jacobi, Martin Nilsson
    et al.
    Andre, Carl
    Döös, Kristofer
    Stockholm University, Faculty of Science, Department of Meteorology .
    Jonsson, Per R.
    Identification of subpopulations from connectivity matrices2012In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 35, no 11, p. 1004-1016Article in journal (Refereed)
    Abstract [en]

    Dispersal on the landscape/seascape scale may lead to complex spatial population structure with non-synchronous demography and genetic divergence. In this study we present a novel approach to identify subpopulations and dispersal barriers based on estimates of dispersal probabilities on the landscape scale. A theoretical framework is presented where the landscape connectivity matrix is analyzed for clusters as a signature of partially isolated subpopulations. Identification of subpopulations is formulated as a minimization problem with a tuneable penalty term that makes it possible to generate population subdivisions with varying degree of dispersal restrictions. We show that this approach produces superior results compared to alternative standard methods. We apply this theory to a dataset of modeled dispersal probabilities for a sessile marine invertebrate with free-swimming larvae in the Baltic Sea. For a range of critical connectivities we produce a hierarchical partitioning into subpopulations spanning dispersal probabilities that are typical for both genetic divergence and demographic independence. The mapping of subpopulations suggests that the Baltic Sea includes a fine-scale (100600 km) mosaic of invisible dispersal barriers. An analysis of the present network of marine protected areas reveal that protection is very unevenly distributed among the suggested subpopulations. Our approach can be used to assess the location and strength of dispersal barriers in the landscape, and identify conservation units when extensive genotyping is prohibitively costly to cover necessary spatial and temporal scales, e.g. in spatial management of marine populations.

  • 41. Jansson, Gunnar
    et al.
    Thulin, Carl-Gustaf
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Population and Conservation Biology.
    Pehrson, Åke
    Factors related to the occurrence of hybrids between brown hares Lepus europaeus and mountain hares L. timidus in Sweden2007In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 30, no 5, p. 709-715Article in journal (Refereed)
    Abstract [en]

    Hybridization occurs among many species, and may have implications for conservation as well as for evolution. Interspecific gene flow between brown hares Lepus europaeus and mountain hares L. timidus has been documented in Sweden and in continental Europe, and has probably to some extent occurred throughout history in sympatric areas. What local factors or ecological relationships that correlate with or trigger hybridization between these species has however been unclear. We studied spatial distribution of hybrids between brown hares and mountain hares in Sweden in relation to characteristics of the sampled localities (hunting grounds). In a sample of 70 brown hares collected from 39 populations in south-central Sweden during 2003–2005, 11 (16%) showed introgressed mtDNA from mountain hares. Among the brown hares from their northern range, i.e. in general the most recent establishments, the corresponding figure was 75% (9/12). The frequency of samples with hybrid ancestry increased significantly with latitude, altitude and hilliness, and were higher (p<0.1) in recently established populations and/or where the proportion of arable land was low. Several site-specific parameters were correlated, e.g. latitude as expected to hilliness, and no parameter explained the occurrence of hybrids exclusively. Instead, the appearance of mountain hare mtDNA among brown hares was associated with a conglomerate of parameters reflecting landscapes atypical for the brown hare, e.g. forest dominated and steep areas where the species quite recently was established. We suggest that these abiotic factors mirror the main aspect influencing hybridization frequency, namely the density or relative frequency of the two species. In atypical brown hare landscapes with recent establishment, mountain hares are probably relatively more common. When one species dominate in numbers, or when both species display low densities, increased frequency of hybridization is expected due to low availability of conspecific partners, a phenomenon referred to as Hubbs' principle.

  • 42.
    Johansson, Helena
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Stoks, Robby
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Nilsson-Örtman, Viktor
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Ingvarsson, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Johansson, Frank
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre of Excellence in Biological Interactions, Dept of Biosciences, Helsinki Univ., PO Box 65, FI-00014 Helsinki.
    Large-scale patterns in genetic variation, gene flow and differentiation in five species of European Coenagrionid damselfly provide mixed support for the central-marginal hypothesis2013In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, no 6, p. 744-755Article in journal (Refereed)
    Abstract [en]

    Recently, an increased effort has been directed towards understanding the distribution of genetic variation within and between populations, particularly at central and marginal areas of a species' distribution. Much of this research is centred on the central-marginal hypothesis, which posits that populations at range margins are sparse, small and genetically diminished compared to those at the centre of a species' distribution range. We tested predictions derived from the central-marginal hypothesis for the distribution of genetic variation and population differentiation in five European Coenagrionid damselfly species. We screened genetic variation (microsatellites) in populations sampled in the centre and margins of the species' latitudinal ranges, assessed genetic diversity (HS) in the populations and the distribution of this genetic diversity between populations (FST). We further assessed genetic substructure and migration with Bayesian assignment methods, and tested for significant associations between genetic substructure and bioclimatic and spatial (altitude and latitude) variables, using general linearized models. We found no general adherence to the central-marginal hypothesis; instead we found that other factors such as historical or current ecological factors often better explain the patterns uncovered. This was illustrated in Coenagrion mercuriale whose colonisation history and behaviour most likely led to the observation of a high genetic diversity in the south and lower genetic diversity with increasing latitude, and in C. armatum and C. pulchellum whose patterns of low genetic diversity coupled with the weakest genetic differentiation at one of their range margins suggested, respectively, possible range shifts and recent, strong selection pressure.

  • 43. Johansson, Helena
    et al.
    Stoks, Robby
    Nilsson-Örtman, Viktor
    Ingvarsson, Pär K.
    Johansson, Frank
    Environmental Science, Umeå University.
    Large-scale patterns in genetic variation, gene flow and differentiation in five species of European Coenagrionid damselfly provide mixed support for the central-marginal hypothesis2013In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, no 6, p. 744-755Article in journal (Refereed)
    Abstract [en]

    Recently, an increased effort has been directed towards understanding the distribution of genetic variation within and between populations, particularly at central and marginal areas of a species’ distribution. Much of this research is centred on the central-marginal hypothesis, which posits that populations at range margins are sparse, small and genetically diminished compared to those at the centre of a species’ distribution range. We tested predictions derived from the central-marginal hypothesis for the distribution of genetic variation and population differentiation in five European Coenagrionid damselfly species. We screened genetic variation (microsatellites) in populations sampled in the centre and margins of the species’ latitudinal ranges, assessed genetic diversity (HS) in the populations and the distribution of this genetic diversity between populations (FST). We further assessed genetic substructure and migration with Bayesian assignment methods, and tested for significant associations between genetic substructure and bioclimatic and spatial (altitude and latitude) variables, using general linearized models. We found no general adherence to the central-marginal hypothesis; instead we found that other factors such as historical or current ecological factors often better explain the patterns uncovered. This was illustrated in Coenagrion mercuriale whose colonisation history and behaviour most likely led to the observation of a high genetic diversity in the south and lower genetic diversity with increasing latitude, and in C. armatum and C. pulchellum whose patterns of low genetic diversity coupled with the weakest genetic differentiation at one of their range margins suggested, respectively, possible range shifts and recent, strong selection pressure.

  • 44.
    Jonason, Dennis
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Ekroos, Johan
    Öckinger, Erik
    Helenius, Juha
    Kuussaari, Mikko
    Tiainen, Juha
    Smith, Henrik G.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Weak functional response to agricultural landscape homogenisation among plants, butterflies and birds2017In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 40, no 10, p. 1221-1230Article in journal (Refereed)
    Abstract [en]

    Measures of functional diversity are expected to predict community responses to land use and environmental change because, in contrast to taxonomic diversity, it is based on species traits rather than their identity. Here, we investigated the impact of landscape homogenisation on plants, butterflies and birds in terms of the proportion of arable field cover in southern Finland at local (0.25 km2) and regional (> 10 000 km2) scales using four functional diversity indices: functional richness, functional evenness, functional divergence and functional dispersion. No uniform response in functional diversity across taxa or scales was found. However, in all cases where we found a relationship between increasing arable field cover and any index of functional diversity, this relationship was negative. Butterfly functional richness decreased with increasing arable field cover, as did butterfly and bird functional evenness. For butterfly functional evenness, this was only evident in the most homogeneous regions. Butterfly and bird functional dispersion decreased in homogeneous regions regardless of the proportion of arable field cover locally. No effect of landscape heterogeneity on plant functional diversity was found at any spatial scale, but plant species richness decreased locally with increasing arable field cover. Overall, species richness responded more consistently to landscape homogenisation than did the functional diversity indices, with both positive and negative effects across species groups. Functional diversity indices are in theory valuable instruments for assessing effects of land use scenarios on ecosystem functioning. However, the applicability of empirical data requires deeper understanding of which traits reliably capture species’ vulnerability to environmental factors and of the ecological interpretation of the functional diversity indices. Our study provides novel insights into how the functional diversity of communities changes in response to agriculturally derived landscape homogenisation; however, the low explanatory power of the functional diversity indices hampers the ability to reliably anticipate impacts on ecosystem functioning.

  • 45.
    Jonsson Cabrajic, Anna V
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Moen, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Palmqvist, Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Predicting growth of mat-forming lichens on a landscape scale: comparing models with different complexities2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, no 5, p. 949-960Article in journal (Refereed)
    Abstract [en]

    During the 20th century, forestry practices has adversely affected lichen-rich habitats. Mat-forming lichens are important components of the vegetation of boreal and arctic ecosystems and are the main reindeer forage during the winter. To support the long-term management of lichens in such habitats we developed models for predicting the growth of two common species. The lichens were transplanted across northern Scandinavia along a west-east gradient varying in precipitation, temperature and irradiance. Growth was recorded seasonally over 16 months and ranged from −4.8 to 34.6% and −12.7 to 34.7% dry weight change for Cetraria stellaris and Cladina islandica, respectively. Growth was light limited below canopies with more than ca 60% cover and highest at the more humid sites when light levels were optimal. The models were based on various meteorological parameters, irradiance, physiological data and lichen hydration status; the latter was derived from a recently developed lichen hydration model. Our models' abilities to predict growth, both annually and seasonally (i.e. in summer), were evaluated in relation to their complexity and their potential usefulness from a management perspective. One parameter related to irradiance (the logarithm of site openness) was valuable in the prediction of annual growth for both species and could, in combination with precipitation, explain 52% of the variation in annual growth for C. stellaris and, in combination with total wet time and the irradiance received while wet, explain 66% of the variation in annual growth for C. islandica. The best simplified model explained 43% of the variation in annual growth for C. stellaris, using stem basal area and the annual normal temperature, and 24% for C. islandica using basal area alone. It is concluded that ensuring sufficient irradiance below the forest canopy is of crucial importance in the long-term management of mat-forming lichens and that simplified models can be used to identify appropriate habitats.

  • 46. Jonsson, Ingemar
    et al.
    Herczeg, Gabor
    O'Hara, Robert B.
    Söderman, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    ter Schure, Arnout F. H.
    Larsson, Per
    Merila, Juha
    Sexual patterns of prebreeding energy reserves in the common frog Rana temporaria along a latitudinal gradient2009In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, no 5, p. 831-839Article in journal (Refereed)
    Abstract [en]

    The ability to store energy is an important life history trait for organisms facing long periods without energy income, and in particular for capital breeders such as temperate zone amphibians, which rely on stored energy during reproduction. However, large scale comparative studies of energy stores in populations with different environmental constraints on energy allocation are scarce. We investigated energy storage patterns in spring (after hibernation and before reproduction) in eight common frog Rana temporaria populations exposed to different environmental conditions along a 1600 km latitudinal gradient across Scandinavia (range of annual activity period is 3-7 months). Analyses of lean body weight (eviscerated body mass), weight of fat bodies, liver weight, and liver fat content, showed that 1) post-hibernation/pre-breeding energy stores increased with increasing latitude in both sexes, 2) males generally had larger energy reserves than females and 3) the difference in energy stores between sexes decreased towards the north. Larger energy reserves towards the north can serve as a buffer against less predictable and/or less benign weather conditions during the short activity period, and may also represent a risk-averse tactic connected with a more pronounced iteroparous life history. In females, the continuous and overlapping vitellogenic activity in the north may also demand more reserves in early spring. The general sexual difference could be a consequence of the fact that, at the time of our sampling, females had already invested their energy into reproduction in the given year (i.e. their eggs were already ovulated), while the males' main reproductive activities (e.g. calling, mate searching, sexual competition) occurred later in the season.

  • 47. Jurasinski, Gerald
    et al.
    Jentsch, Anke
    Retzer, Vroni
    Beierkuhnlein, Carl
    Detecting spatial patterns in species composition with multiple plot similarity coefficients and singularity measures2012In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Ecography, Vol. 35, no 1, p. 73-88Article in journal (Refereed)
    Abstract [en]

    Recently, several multiple plot similarity indices have been presented that cure some of the problems associated with the approaches for the calculation of compositional similarity for groups of plots by averaging pairwise similarities. These new indices calculate the similarity between more than two plots whilst considering the species composition on all compared plots. The resulting similarity value is true for the whole group of plots considered (called neighborhood in the following). Here, we review the possibilities for multiple plot similarity calculation and additionally explore coefficients that examine multiple plot similarity between a reference plot (named focal plot in the following) and any number of surrounding plots. The latter represent measures of singularity. Further, we establish a framework for applying these two kinds of multiple plot measures to gridded data including an algorithm for testing the significance of calculated values against random expectations. The capability of multiple plot measures for detecting species compositional gradients and local/regional hotspots within this framework is tested. For this purpose, several artificial data sets with known gradients in species composition (random, gradient, central hotspot, hotspot bottom right) are constructed on the basis of a real data set from a Tundra ecosystem in northern Sweden (Abisko). The coefficients that best reflect the positions of the plots on the realized gradients in species composition are considered as performing best with regard to pattern detection. The tested measures of multiple plot similarity and singularity produced considerably different results when applied to one real and 4 artificial data sets. The newly proposed symmetric singularity coefficient has the best overall performance which makes it suitable for local/regional hotspot detection and for incorporating local to regional similarity analyses in reserve selection procedures.

  • 48. Jönsson, Ingemar K.
    et al.
    Herczeg, Gabor
    O'Hara, Robert B.
    Söderman, Fredrik
    ter Schure, Arnout F.H.
    Larsson, Per
    Lund Univ, Dept Ecol, SE-22362 Lund.
    Merilä, Juha
    Sexual patterns of prebreeding energy reserves in the common frog Rana temporaria along a latitudinal gradient2009In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, no 5, p. 831-839Article in journal (Refereed)
    Abstract [en]

    The ability to store energy is an important life history trait for organisms facing long periods without energy income, and in particular for capital breeders such as temperate zone amphibians, which rely on stored energy during reproduction. However, large scale comparative studies of energy stores in populations with different environmental constraints on energy allocation are scarce. We investigated energy storage patterns in spring (after hibernation and before reproduction) in eight common frog Rana temporaria populations exposed to different environmental conditions along a 1600 km latitudinal gradient across Scandinavia (range of annual activity period is 3-7 months). Analyses of lean body weight (eviscerated body mass), weight of fat bodies, liver weight, and liver fat content, showed that 1) post-hibernation/pre-breeding energy stores increased with increasing latitude in both sexes, 2) males generally had larger energy reserves than females and 3) the difference in energy stores between sexes decreased towards the north. Larger energy reserves towards the north can serve as a buffer against less predictable and/or less benign weather conditions during the short activity period, and may also represent a risk-averse tactic connected with a more pronounced iteroparous life history. In females, the continuous and overlapping vitellogenic activity in the north may also demand more reserves in early spring. The general sexual difference could be a consequence of the fact that, at the time of our sampling, females had already invested their energy into reproduction in the given year (i.e. their eggs were already ovulated), while the males' main reproductive activities (e.g. calling, mate searching, sexual competition) occurred later in the season.

  • 49.
    Jönsson, K. Ingemar
    Lund University.
    Population density and species composition of moss-living tardigrades in a boreo-nemoral forest2003In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 26, no 3, p. 356-364Article in journal (Refereed)
    Abstract [en]

    This study investigates for the first time the tardigrade fauna in a variety of different mosses from a coniferous forest and an adjacent clear-cut area in southern Sweden. Tardigrades were found in a majority of the samples. Sixteen species were recorded, of which the cosmopolitan species Macrobiotus hufelandi was the far most common. Some mosses, particularly species with "wefts" growth form, contained more tardigrades than other mosses, indicating that growth form may have an impact on tardigrade abundance. Mosses of the same species collected from a forest and from a clear-cut, respectively, did not show a general trend in the overall abundance of tardigrades, but the forest tended to contain more species. Five species of tardigrades (Murrayon dianae, Isohypsibius sattleri, Platicrista angustata, Diphascon belgicae and Diphascon pingue) never previously reported from Sweden were recorded.

  • 50.
    Jönsson, K. Ingemar
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
    Herczeg, Gabor
    Finland.
    O´Hara, Robert
    Finland.
    Söderman, Fredrik
    Uppsala University.
    ter Schure, Arnout
    USA.
    Larsson, Per
    Lund University.
    Merilä, Juha
    Finland.
    Sexual patterns of prebreeding energy reserves in the common frog Rana temporaria along a latitudinal gradient2009In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 32, no 5, p. 831-839Article in journal (Refereed)
    Abstract [en]

    The ability to store energy is an important life history trait for organisms facing long periods without energy income, and in particular for capital breeders such as temperate zone amphibians, which rely on stored energy during reproduction. However, large scale comparative studies of energy stores in populations with different environmental constraints on energy allocation are scarce. We investigated energy storage patterns in spring (after hibernation and before reproduction) in eight common frog (Rana temporaria) populations exposed to different environmental conditions along a 1600 km latitudinal gradient across Scandinavia (range of annual activity period 3-7 months). Analyses of lean body weight (eviscerated body mass), weight of fat bodies, liver weight, and liver fat content, showed that (i) post-hibernation/pre-breeding energy stores increased with increasing latitude in both sexes, (ii) males generally had larger energy reserves than females and (iii) the difference in energy stores between sexes decreased towards the north. Larger energy reserves towards the north can serve as a buffer against less predictable and/or less benign weather conditions during the short activity period, and may also represent a risk-averse tactic connected with a more pronounced iteroparous life history. In females, the continuous and overlapping vitellogenic activity in the north may also demand more reserves in early spring. The general sexual difference could be a consequence of the fact that, at the time of our sampling, females had already invested their energy into reproduction in the given year (i.e. their eggs were already ovulated), while the males' main reproductive activities (e.g. calling, mate searching, sexual competition) occurred later in the season.

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