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  • 1.
    Johansson, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Adjusting to the extreme: Thermal adaptation in a freshwater gastropod2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Temperature is a ubiquitous force influencing biological processes ranging from cellular responses to life span. The thermal environment for many organisms is predicted to change with globally increasing temperatures and studies conducted in natural systems incorporating various evolutionary forces, such as gene flow, is needed. In my thesis, I investigate how snails (Radix balthica) originating from distinct geothermal environments within Lake Mývatn in northern Iceland have adapted, both genetically and phenotypically, to the respective thermal regime. Locations were classified as either cold, warm or seasonal depending on the average and variance in temperature. A high resolution spatial distribution of genetic variation within Mývatn was obtained using both neutral and outlier AFLPs. In addition, the genetic profile enabled me identify warm origin snails irrespective of geographic location in Iceland. Warm environments were often more stressful than cold or seasonal environments but snails originating from a high temperature location benefited from increased performance elsewhere. Patterns of growth were identical in both common garden and reciprocal transplant experiment; warm origin snails grew faster than both cold and seasonal origin snails. This result is in concordance with quantitative genetics models of thermal adaptation but suggesting cogradient rather than countergradient variation. Although warm origin snails generally had superior performance, survival at cold temperatures (< 12 °C) was reduced. All snails matured at similar size in the common garden experiment but cold origin snails were observed to mature later and lay fewer eggs. Also, snails had a common optimum for growth rate at 20 °C irrespective of thermal origin. This is arguably the reason why snails were observed to have a common thermal preference. Interestingly, warm origin snails had a reduced tolerance to high temperatures compared to cold and seasonal origin snails which did not differ in tolerance. Putatively, natural selection has reduced a putatively unnecessary trait (high temperature tolerance in a stable thermal environment) in favour of higher growth rate and performance in warm habitats. In conclusion, the price of high performance in a warm environment was paid in terms of reduced survival at low temperatures and a potential disadvantage of reduced genetic variability.

  • 2.
    Johansson, Magnus P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Laurila, Anssi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Maximum thermal tolerance trades off with chronic tolerance of high temperature in contrasting thermal populations of Radix balthica2017In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 7, no 9, p. 3149-3156Article in journal (Refereed)
    Abstract [en]

    Thermal adaptation theory predicts that thermal specialists evolve in environments with low temporal and high spatial thermal variation, whereas thermal generalists are favored in environments with high temporal and low spatial variation. The thermal environment of many organisms is predicted to change with globally increasing temperatures and thermal specialists are presumably at higher risk than thermal generalists. Here we investigated critical thermal maximum (CTmax) and preferred temperature (T-p) in populations of the common pond snail (Radix balthica) originating from a small-scale system of geothermal springs in northern Iceland, where stable cold (ca. 7 degrees C) and warm (ca. 23 degrees C) habitats are connected with habitats following the seasonal thermal variation. Irrespective of thermal origin, we found a common T-p for all populations, corresponding to the common temperature optimum (T-opt) for fitness-related traits in these populations. Warm-origin snails had lowest CTmax. As our previous studies have found higher chronic temperature tolerance in the warm populations, we suggest that there is a trade-off between high temperature tolerance and performance in other fitness components, including tolerance to chronic thermal stress. T-p and CTmax were positively correlated in warm-origin snails, suggesting a need to maintain a minimum "warming tolerance" (difference in CTmax and habitat temperature) in warm environments. Our results highlight the importance of high mean temperature in shaping thermal performance curves.

  • 3.
    Johansson, Magnus P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Population and Conservation Biology.
    Mcmahon, Barry J.
    Höglund, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Population and Conservation Biology.
    Segelbacher, Gernot
    Amplification success of multilocus genotypes from feathers found in the field compared with feathers obtained from shot birds2012In: Ibis, ISSN 0019-1019, E-ISSN 1474-919X, Vol. 154, no 1, p. 15-20Article in journal (Refereed)
    Abstract [en]

    Effective DNA extraction methods from bird feathers have facilitated non-invasive sampling, leading to the suggestion that feathers are a great source for genetic studies. However, few studies have assessed whether all feathers can be used or provide equal numbers of useful templates. In this study, feathers collected in various ways from Red Grouse Lagopus lagopus were examined to establish the quality of DNA extracted. Individual samples were classified into two categories according to whether they were collected from shot birds or found in the field. DNA was extracted from all samples and genotyped at 19 microsatellite loci. PCR products were analysed on a MegaBACE 1000. A total of 93% of the shot category produced a genotype that was considered successful (i.e. 15 of 18 loci) and 23% of the collected category produced successful genotypes under the same criteria. There was a significant difference between shot and collected samples in genotyping success and the observed number of missing loci. Recommendations and best practices are discussed along with the utility of bird feathers as a source of DNA for population and conservation biology.

  • 4.
    Magnus, Johansson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Friederike, Ermold
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Kristjánsson, Bjarni
    Hólar University Collage, Iceland.
    Anssi, Laurila
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Local adaptation of gastropod life history to contrasting thermal environments in a geothermal lakeArticle in journal (Refereed)
  • 5.
    Magnus, Johansson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Quintela, María
    Institute of Marine Research, Norway.
    Anssi, Laurila
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Genetic divergance and isolation by environment in geothermal populations of the common pond snail (Radix balthica)Manuscript (preprint) (Other academic)
  • 6. McMahon, Barry J.
    et al.
    Johansson, Magnus P.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Population and Conservation Biology.
    Piertney, Stuart B.
    Buckley, Kieran
    Höglund, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Population and Conservation Biology.
    Genetic variation among endangered Irish red grouse (Lagopus lagopus hibernicus) populations: implications for conservation and management2012In: Conservation Genetics, ISSN 1566-0621, E-ISSN 1572-9737, Vol. 13, no 3, p. 639-647Article in journal (Refereed)
    Abstract [en]

    Extant populations of Irish red grouse (Lagopus lagopus hibernicus) are both small and fragmented, and as such may have an increased risk of extinction through the effects of inbreeding depression and compromised adaptive potential. Here we used 19 microsatellite markers to assay genetic diversity across 89 georeferenced samples from putatively semi-isolated areas throughout the Republic of Ireland and we also genotyped 27 red grouse from Scotland using the same markers. The genetic variation within Ireland was low in comparison to previously published data from Britain and the sample of Scottish red grouse, and comparable to threatened European grouse populations of related species. Irish and Scottish grouse were significantly genetically differentiated (F-ST = 0.07, 95% CI = 0.04-0.10). There was evidence for weak population structure within Ireland with indications of four distinct genetic clusters. These correspond approximately to grouse populations inhabiting suitable habitat patches in the North West, Wicklow Mountains, Munster and Cork, respectively, although some admixture was detected. Pair-wise F-ST values among these populations ranged from 0.02 to 0.04 and the overall mean allelic richness was 5.5. Effective population size in the Munster area was estimated to be 62 individuals (95% CI = 33.6-248.8). Wicklow was the most variable population with an AR value of 5.4 alleles/locus. Local (Munster) neighbourhood size was estimated to 31 individuals corresponding to an average dispersal distance of 31 km. In order to manage and preserve Irish grouse we recommend that further fragmentation and destruction of habitats need to be prevented in conjunction with population management, including protection of the integrity of the existing population by refraining from augmenting it with individuals from mainland Britain to maximise population size.

  • 7. O'Gorman, Eoin J.
    et al.
    Pichler, Doris E.
    Adams, Georgina
    Benstead, Jonathan P.
    Cohen, Haley
    Craig, Nicola
    Cross, Wyatt F.
    Demars, Benoit O. L.
    Friberg, Nikolai
    Gislason, Gisli Mar
    Gudmundsdottir, Rakel
    Hawczak, Adrianna
    Hood, James M.
    Hudson, Lawrence N.
    Johansson, Liselotte
    Johansson, Magnus P.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Population and Conservation Biology.
    Junker, James R.
    Laurila, Anssi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Population and Conservation Biology.
    Manson, J. Russell
    Mavromati, Efpraxia
    Nelson, Daniel
    Olafsson, Jon S.
    Perkins, Daniel M.
    Petchey, Owen L.
    Plebani, Marco
    Reuman, Daniel C.
    Rall, Bjoern C.
    Stewart, Rebecca
    Thompson, Murray S. A.
    Woodward, Guy
    Impacts of Warming on the Structure and Functioning of Aquatic Communities: Individual-to Ecosystem-Level Responses2012In: Advances in Ecological Research, Vol 47: Global Change in Multispecies Systems, Pt 2, Elsevier, 2012, p. 81-176Chapter in book (Refereed)
    Abstract [en]

    Environmental warming is predicted to rise dramatically over the next century, yet few studies have investigated its effects in natural, multi-species systems. We present data collated over an 8-year period from a catchment of geothermally heated streams in Iceland, which acts as a natural experiment on the effects of warming across different organisational levels and spatiotemporal scales. Body sizes and population biomasses of individual species responded strongly to temperature, with some providing evidence to support temperature size rules. Macroinvertebrate and meiofaunal community composition also changed dramatically across the thermal gradient. Interactions within the warm streams in particular were characterised by food chains linking algae to snails to the apex predator, brown trout These chains were missing from the colder systems, where snails were replaced by much smaller herbivores and invertebrate omnivores were the top predators. Trout were also subsidised by terrestrial invertebrate prey, which could have an effect analogous to apparent competition within the aquatic prey assemblage. Top-down effects by snails on diatoms were stronger in the warmer streams, which could account for a shallowing of mass-abundance slopes across the community. This may indicate reduced energy transfer efficiency from resources to consumers in the warmer systems and/or a change in predator-prey mass ratios. All the ecosystem process rates investigated increased with temperature, but with differing thermal sensitivities, with important implications for overall ecosystem functioning (e.g. creating potential imbalances in elemental fluxes). Ecosystem respiration rose rapidly with temperature, leading to increased heterotrophy. There were also indications that food web stability may be lower in the warmer streams.

  • 8.
    Quintela, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Johansson, Magnus P.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Kristjansson, Bjarni K.
    Barreiro, Rodolfo
    Laurila, Anssi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    AFLPs and Mitochondrial Haplotypes Reveal Local Adaptation to Extreme Thermal Environments in a Freshwater Gastropod2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 7, p. e101821-Article in journal (Refereed)
    Abstract [en]

    The way environmental variation shapes neutral and adaptive genetic variation in natural populations is a key issue in evolutionary biology. Genome scans allow the identification of the genetic basis of local adaptation without previous knowledge of genetic variation or traits under selection. Candidate loci for divergent adaptation are expected to show higher F-ST than neutral loci influenced solely by random genetic drift, migration and mutation. The comparison of spatial patterns of neutral markers and loci under selection may help disentangle the effects of gene flow, genetic drift and selection among populations living in contrasting environments. Using the gastropod Radix balthica as a system, we analyzed 376 AFLP markers and 25 mtDNA COI haplotypes for candidate loci and associations with local adaptation among contrasting thermal environments in Lake Myvatn, a volcanic lake in northern Iceland. We found that 2% of the analysed AFLP markers were under directional selection and 12% of the mitochondrial haplotypes correlated with differing thermal habitats. The genetic networks were concordant for AFLP markers and mitochondrial haplotypes, depicting distinct topologies at neutral and candidate loci. Neutral topologies were characterized by intense gene flow revealed by dense nets with edges connecting contrasting thermal habitats, whereas the connections at candidate loci were mostly restricted to populations within each thermal habitat and the number of edges decreased with temperature. Our results suggest microgeographic adaptation within Lake Myvatn and highlight the utility of genome scans in detecting adaptive divergence.

1 - 8 of 8
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