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  • 1. Anderson, Bruce
    et al.
    Alexandersson, Ronny
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Johnson, Steven D
    Evolution and coexistence of pollination ecotypes in an African Gladiolus (Iridaceae)2010In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 64, no 4, p. 960-972Article in journal (Refereed)
    Abstract [en]

    Pollinator-mediated selection has been suggested as a key driver of speciation in plants. We examined the potential role of hawkmoth pollinators in driving allopatric divergence and maintaining sympatric coexistence of morphotypes in the African iris Gladiolus longicollis. Floral tube length in this species varies from 35 mm to 130 mm across its geographic range and reflects the prevailing tongue lengths of local hawkmoth assemblages. The distribution of floral tube lengths is bimodal with two relatively discrete categories—long (about 90 mm) or short (about 50 mm)—that match the bimodal distribution of hawkmoth tongue lengths in eastern South Africa. At a contact site between these two floral morphs, we found few individuals of intermediate length, suggesting limited gene flow between morphs despite their interfertility. A difference in flowering phenology appears to be the main isolating barrier between morphs at this site. Long- and short-tubed morphs differed markedly in the chemical composition of their floral fragrance, a trait that could be used as a cue for morph-specific foraging by hawkmoths. Positive directional selection on tube length was found to occur in both morphs.

  • 2. Antoniazza, Sylvain
    et al.
    Burri, Reto
    Fumagalli, Luca
    Goudet, Jérôme
    Roulin, Alexandre
    Local adaptation maintains clinal variation in melanin-based coloration of European barn owls (Tyto alba).2010In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 64, no 7, p. 1944-1954Article in journal (Refereed)
    Abstract [en]

    Ecological parameters vary in space, and the resulting heterogeneity of selective forces can drive adaptive population divergence. Clinal variation represents a classical model to study the interplay of gene flow and selection in the dynamics of this local adaptation process. Although geographic variation in phenotypic traits in discrete populations could be remainders of past adaptation, maintenance of adaptive clinal variation requires recurrent selection. Clinal variation in genetically determined traits is generally attributed to adaptation of different genotypes to local conditions along an environmental gradient, although it can as well arise from neutral processes. Here, we investigated whether selection accounts for the strong clinal variation observed in a highly heritable pheomelanin-based color trait in the European barn owl by comparing spatial differentiation of color and of neutral genes among populations. Barn owl's coloration varies continuously from white in southwestern Europe to reddish-brown in northeastern Europe. A very low differentiation at neutral genetic markers suggests that substantial gene flow occurs among populations. The persistence of pronounced color differentiation despite this strong gene flow is consistent with the hypothesis that selection is the primary force maintaining color variation among European populations. Therefore, the color cline is most likely the result of local adaptation.

  • 3. Archer, C. R.
    et al.
    Zajitschek, Felix
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Sakaluk, S. K.
    Royle, N. J.
    Hunt, J.
    Sexual selection affects the evolution of lifespan and ageing in the decorated cricket gryllodes sigillatus2012In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 66, no 10, p. 3088-3100Article in journal (Refereed)
    Abstract [en]

    Recent work suggests that sexual selection can influence the evolution of ageing and lifespan by shaping the optimal timing and relative costliness of reproductive effort in the sexes. We used inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, lifespan, and ageing within and between the sexes. Sexual selection theory predicts that males should die sooner and age more rapidly than females. However, a reversal of this pattern may be favored if reproductive effort increases with age in males but not in females. We found that male calling effort increased with age, whereas female fecundity decreased, and that males lived longer and aged more slowly than females. These divergent life-history strategies were underpinned by a positive genetic correlation between early-life reproductive effort and ageing rate in both sexes, although this relationship was stronger in females. Despite these sex differences in life-history schedules, age-dependent reproductive effort, lifespan, and ageing exhibited strong positive intersexual genetic correlations. This should, in theory, constrain the independent evolution of these traits in the sexes and may promote intralocus sexual conflict. Our study highlights the importance of sexual selection to the evolution of sex differences in ageing and lifespan in G. sigillatus.

  • 4.
    Arnqvist, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Assortative mating by fitness and sexually antagonistic genetic variation2011In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, no 7, p. 2111-2116Article in journal (Refereed)
    Abstract [en]

    Recent documentations of sexually antagonistic genetic variation in fitness have spurred an interest in the mechanisms that may act to maintain such variation in natural populations. Using individual-based simulations, I show that positive assortative mating by fitness increases the amount of sexually antagonistic genetic variance in fitness, primarily by elevating the equilibrium frequency of heterozygotes, over most of the range of sex-specific selection and dominance. Further, although the effects of assortative mating by fitness on the protection conditions of polymorphism in sexually antagonistic loci were relatively minor, it widens the protection conditions under most reasonable scenarios (e. g., under heterozygote superiority when fitness is averaged across the sexes) but can also somewhat narrow the protection conditions under other circumstances. The near-ubiquity of assortative mating in nature suggests that it may contribute to upholding standing sexually antagonistic genetic variation in fitness.

  • 5.
    Arnqvist, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Sexual conflict and sexual selection: Lost in the chase2004In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 58, no 6, p. 1383-1388Article in journal (Refereed)
  • 6.
    Arnqvist, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Danielsson, I
    Copulatory behavior, genital morphology, and male fertilization success in water striders1999In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 53, no 1, p. 147-156Article in journal (Refereed)
  • 7.
    Arnqvist, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Dowling, Damian K.
    Eady, Paul
    Gay, Laurene
    Tregenza, Tom
    Tuda, Midori
    Hosken, David J.
    Genetic architecture of metabolic rate: environment specific epistasis between mitochondrial and nuclear genes in an insect2010In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 64, no 12, p. 3354-3363Article in journal (Refereed)
    Abstract [en]

    The extent to which mitochondrial DNA (mtDNA) variation is involved in adaptive evolutionary change is currently being reevaluated. In particular, emerging evidence suggests that mtDNA genes coevolve with the nuclear genes with which they interact to form the energy producing enzyme complexes in the mitochondria. This suggests that intergenomic epistasis between mitochondrial and nuclear genes may affect whole-organism metabolic phenotypes. Here, we use crossed combinations of mitochondrial and nuclear lineages of the seed beetle Callosobruchus maculatus and assay metabolic rate under two different temperature regimes. Metabolic rate was affected by an interaction between the mitochondrial and nuclear lineages and the temperature regime. Sequence data suggests that mitochondrial genetic variation has a role in determining the outcome of this interaction. Our genetic dissection of metabolic rate reveals a high level of complexity, encompassing genetic interactions over two genomes, and genotype x genotype x environment interactions. The evolutionary implications of these results are twofold. First, because metabolic rate is at the root of life histories, our results provide insights into the complexity of life-history evolution in general, and thermal adaptation in particular. Second, our results suggest a mechanism that could contribute to the maintenance of nonneutral mtDNA polymorphism.

  • 8.
    Arnqvist, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Fricke, C
    Arnqvist, G
    Patterns of divergence in the effects of mating on female reproductive performance in flour beetles2002In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 56, no 1, p. 111-120Article in journal (Refereed)
  • 9.
    Arnqvist, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Rowe, L
    Correlated evolution of male and female morphologies in water striders2002In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 56, no 5, p. 936-947Article in journal (Refereed)
  • 10. Aronsen, Tonje
    et al.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Mobley, Kenyon B.
    Ratikainen, Irja I.
    Rosenqvist, Gunilla
    Sex Ratio And Density Affect Sexual Selection In A Sex-Role Reversed Fish2013In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 67, no 11, p. 3243-3257Article in journal (Refereed)
    Abstract [en]

    Understanding how demographic processes influence mating systems is important to decode ecological influences on sexual selection in nature. We manipulated sex ratio and density in experimental populations of the sex-role reversed pipefish Syngnathus typhle. We quantified sexual selection using the Bateman gradient (beta'ss), the opportunity for selection (I), and sexual selection (Is), and the maximum standardized sexual selection differential (s(max)). We also measured selection on body length using standardized selection differentials (s') and mating differentials (m'), and tested whether the observed I and Is differ from values obtained by simulating random mating. We found that I, Is, and s'(max), but not beta'(ss), were higher for females under female than male bias and the opposite for males, but density did not affect these measures. However, higher density decreased sexual selection (m similar to but not s') on female length, but selection on body length was not affected by sex ratio. Finally, Is but not I was higher than expected from random mating, and only for females under female bias. This study demonstrates that both sex ratio and density affect sexual selection and that disentangling interrelated demographic processes is essential to a more complete understanding of mating behavior and the evolution of mating systems.

  • 11.
    Backström, Niclas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Lindell, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Zhang, Yu
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Palkopoulou, Eleftheria
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Qvarnström, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Sætre, Glenn-Peter
    Ellegren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    A high-density scan of the Z chromosome in ficedula flycatchers reveals candidate loci for diversifying selection2010In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 64, no 12, p. 3461-3475Article in journal (Refereed)
    Abstract [en]

    Theoretical and empirical data suggest that genes located on sex chromosomes may play an important role both for sexually selected traits and for traits involved in the build-up of hybrid incompatibilities. We investigated patterns of genetic variation in 73 genes located on the Z chromosomes of two species of the flycatcher genus Ficedula, the pied flycatcher and the collared flycatcher. Sequence data were evaluated for signs of selection potentially related to genomic differentiation in these young sister species, which hybridize despite reduced fitness of hybrids. Seven loci were significantly more divergent between the two species than expected under neutrality and they also displayed reduced nucleotide diversity, consistent with having been influenced by directional selection. Two of the detected candidate regions contain genes that are associated with plumage coloration in birds. Plumage characteristics play an important role in species recognition in these flycatchers suggesting that the detected genes may have been involved in the evolution of sexual isolation between the species.

  • 12.
    Balogh, Alexandra C.V.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gamberale-Stille, Gabriella
    Stockholm University, Faculty of Science, Department of Zoology.
    Tullberg, Birgitta S.
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Feature theory and the two-step hypothesis of Müllerian mimicry evolution2010In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 64, no 3, p. 810-822Article in journal (Refereed)
    Abstract [en]

    The two-step hypothesis of Müllerian mimicry evolution states that mimicry starts with a major mutational leap between adaptive peaks, followed by gradual fine-tuning. The hypothesis was suggested to solve the problem of apostatic selection producing a valley between adaptive peaks, and appears reasonable for a one-dimensional phenotype. Extending the hypothesis to the realistic scenario of multidimensional phenotypes controlled by multiple genetic loci can be problematic, because it is unlikely that major mutational leaps occur simultaneously in several traits. Here we consider the implications of predator psychology on the evolutionary process. According to feature theory, single prey traits may be used by predators as features to classify prey into discrete categories. A mutational leap in such a trait could initiate mimicry evolution. We conducted individual-based evolutionary simulations in which virtual predators both categorize prey according to features and generalize over total appearances. We found that an initial mutational leap towards feature similarity in one dimension facilitates mimicry evolution of multidimensional traits. We suggest that feature-based predator categorization together with predator generalization over total appearances solves the problem of applying the two-step hypothesis to complex phenotypes, and provides a basis for a theory of the evolution of mimicry rings.

  • 13. Barnes, Ian
    et al.
    Duda, Anna
    Pybus, Oliver G.
    Thomas, Mark G.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Ancient urbanization predicts genetic resistance to tuberculosis2011In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, no 3, p. 842-848Article in journal (Refereed)
    Abstract [en]

    A link between urban living and disease is seen in recent and historical records, but the presence of this association in prehistory has been difficult to assess. If the transition to urban living does result in an increase in disease-based mortality, we might expect to see evidence of increased disease resistance in longer-term urbanized populations, as the result of natural selection. To test this, we determined the frequency of an allele (SLC11A1 1729 + 55del4) associated with natural resistance to intracellular pathogens such as tuberculosis and leprosy. We found a highly significantly correlation with duration of urban settlement-populations with a long history of living in towns are better adapted to resisting these infections. This correlation remains strong when we correct for autocorrelation in allele frequencies due to shared population history. Our results therefore support the interpretation that infectious disease loads became an increasingly important cause of human mortality after the advent of urbanization, highlighting the importance of population density in determining human health and the genetic structure of human populations.

  • 14.
    Bastiaans, Eric
    et al.
    Laboratory of Genetics, Wageningen University, Wageningen.
    Debets, Alfons J. M.
    Aanen, Duur K.
    Experimental demonstration of the benefits of somatic fusion and the consequences for allorecognition2015In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 69, no 4, p. 1091-1099Article in journal (Refereed)
    Abstract [en]

    Allorecognition, the ability to distinguish “self” from “nonself” based on allelic differences at allorecognition loci, is common in all domains of life. Allorecognition restricts the opportunities for social parasitism, and is therefore crucial for the evolution of cooperation. However, the maintenance of allorecognition diversity provides a paradox. If allorecognition is costly relative to cooperation, common alleles will be favored. Thus, the cost of allorecognition may reduce the genetic variation upon which allorecognition crucially relies, a prediction now known as “Crozier’s paradox.” We establish the relative costs of allorecognition, and their consequences for the short-term evolution of recognition labels theoretically predicted by Crozier. We use fusion among colonies of the fungus Neurospora crassa, regulated by highly variable allorecognition genes, as an experimental model system. We demonstrate that fusion among colonies is mutually beneficial, relative to absence of fusion upon allorecognition. This benefit is due not only to absence of mutual antagonism, which occurs upon allorecognition, but also to an increase in colony size per se. We then experimentally demonstrate that the benefit of fusion selects against allorecognition diversity, as predicted by Crozier. We discuss what maintains allorecognition diversity.

  • 15.
    Bergek, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Björklund, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Cryptic barriers to dispersal within a lake allow genetic differentiation of Eurasian perch2007In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 61, no 8, p. 2035-2041Article in journal (Refereed)
    Abstract [en]

    Gene flow between coexisting or nearby populations normally prevents genetic divergence and local adaptation. Despite this, there are an increasing number of reports of sympatric sister taxa, indicating potential divergence and speciation in the face of gene flow. A large number of such reported cases involve lake-dwelling fish, which are expected to run into few physical barriers to dispersal within their aquatic habitat. However, such cases may not necessarily reflect sympatric speciation if cryptic dispersal barriers are common in lakes and other aquatic systems. In this study, we examined genetic differentiation in perch (Perca fluviatilis L.) from nine locations in a single, small lake (24 km(2)), using microsatellites. We detected significant genetic differentiation in all but two pairwise comparisons. These patterns were not consistent with divergence by distance or the existence of kin groups. Instead, they suggest that cryptic barriers to dispersal exist within the lake, allowing small-scale genetic divergence. Such an observation suggests that allopatric (or parapatric) divergence may be possible, even in small, apparently homogenous environments such as lakes. This has important consequences for how we currently view evidence from nature for sympatric speciation.

  • 16.
    Berger, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Berg, Elena C
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Widegren, William
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Arnqvist, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Maklakov, Alexei A
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Multivariate intralocus sexual conflict in seed beetles2014In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 68, no 12, p. 3457-69Article in journal (Refereed)
    Abstract [en]

    Intralocus sexual conflict (IaSC) is pervasive because males and females experience differences in selection but share much of the same genome. Traits with integrated genetic architecture should be reservoirs of sexually antagonistic genetic variation for fitness, but explorations of multivariate IaSC are scarce. Previously, we showed that upward artificial selection on male life span decreased male fitness but increased female fitness compared with downward selection in the seed beetle Callosobruchus maculatus. Here, we use these selection lines to investigate sex-specific evolution of four functionally integrated traits (metabolic rate, locomotor activity, body mass, and life span) that collectively define a sexually dimorphic life-history syndrome in many species. Male-limited selection for short life span led to correlated evolution in females toward a more male-like multivariate phenotype. Conversely, males selected for long life span became more female-like, implying that IaSC results from genetic integration of this suite of traits. However, while life span, metabolism, and body mass showed correlated evolution in the sexes, activity did not evolve in males but, surprisingly, did so in females. This led to sexual monomorphism in locomotor activity in short-life lines associated with detrimental effects in females. Our results thus support the general tenet that widespread pleiotropy generates IaSC despite sex-specific genetic architecture.

  • 17.
    Berger, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Grieshop, Karl
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Lind, Martin I.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Goenaga, Julieta
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Maklakov, Alexei A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Arnqvist, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Intralocus Sexual Conflict and Environmental Stress2014In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 68, no 8, p. 2184-2196Article in journal (Refereed)
    Abstract [en]

    Intralocus sexual conflict (IaSC) occurs when selection at a given locus favors different alleles in males and females, placing a fundamental constraint on adaptation. However, the relative impact of IaSC on adaptation may become reduced in stressful environments that expose conditionally deleterious mutations to selection. The genetic correlation for fitness between males and females (r(MF)) provides a quantification of IaSC across the genome. We compared IaSC at a benign (29 degrees C) and a stressful (36 degrees C) temperature by estimating r(MF)s in two natural populations of the seed beetle Callosobruchus maculatus using isofemale lines. In one population, we found substantial IaSC under benign conditions signified by a negative r(MF) (-0.51) and, as predicted, a significant reduction of IaSC under stress signified by a reversed and positive r(MF) (0.21). The other population displayed low IaSC at both temperatures (r(MF): 0.38; 0.40). In both populations, isofemale lines harboring alleles beneficial to males but detrimental to females at benign conditions tended to show overall low fitness under stress. These results offer support for low IaSC under stress and suggest that environmentally sensitive and conditionally deleterious alleles that are sexually selected in males mediate changes in IaSC. We discuss implications for adaptive evolution in sexually reproducing populations.

  • 18.
    Berger, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Postma, Erik
    Blanckenhorn, Wolf U.
    Walters, Richard J.
    Quantitative genetic divergence and standing genetic (CO)variance in thermal reaction norms along latitude2013In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 67, no 8, p. 2385-2399Article in journal (Refereed)
    Abstract [en]

    Although the potential to adapt to warmer climate is constrained by genetic trade-offs, our understanding of how selection and mutation shape genetic (co)variances in thermal reaction norms is poor. Using 71 isofemale lines of the fly Sepsis punctum, originating from northern, central, and southern European climates, we tested for divergence in juvenile development rate across latitude at five experimental temperatures. To investigate effects of evolutionary history in different climates on standing genetic variation in reaction norms, we further compared genetic (co) variances between regions. Flies were reared on either high or low food resources to explore the role of energy acquisition in determining genetic trade-offs between different temperatures. Although the latter had only weak effects on the strength and sign of genetic correlations, genetic architecture differed significantly between climatic regions, implying that evolution of reaction norms proceeds via different trajectories at high latitude versus low latitude in this system. Accordingly, regional genetic architecture was correlated to region-specific differentiation. Moreover, hot development temperatures were associated with low genetic variance and stronger genetic correlations compared to cooler temperatures. We discuss the evolutionary potential of thermal reaction norms in light of their underlying genetic architectures, evolutionary histories, and the materialization of trade-offs in natural environments.

  • 19.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Egg competition in a sex-role reversed pipefish: subdominant females trade reproduction for growth1991In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 45, no 3, p. 770-774Article in journal (Refereed)
  • 20.
    Björklund, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Be careful with your principal components2019In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 73, no 10, p. 2151-2158Article in journal (Other academic)
    Abstract [en]

    Principal components analysis (PCA) is a common method to summarize a larger set of correlated variables into a smaller and more easily interpretable axes of variation. However, the different components need to be distinct from each other to be interpretable otherwise they only represent random directions. This is a fundamental assumption of PCA and, thus, needs to be tested every time. Sample correlation matrices will always result in a pattern of decreasing eigenvalues even if there is no structure. Tests are, therefore, needed to discern real patterns from illusionary ones. Furthermore, the loadings of the vectors need to be larger than expected by random data to be useful in the calculation of PC-scores. PC-scores calculated from nondistinct PC's have very large standard errors and cannot be used for biological interpretations. I give a number of examples to illustrate the potential problems with PCA. Robustness of the PC's increases with increasing sample size but not with the number of traits. I review a few simple test statistics appropriate for testing PC's and use a real-world example to illustrate how this can be done using randomization tests. PCA can be very useful but great care is needed to avoid spurious results.

  • 21.
    Björklund, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Comparative analyses in birds: what is in a correlation?2002In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 56, p. 1883-1884Article, book review (Refereed)
  • 22.
    Björklund, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Evolution, phylogeny, sexual dimorphism and mating system in the grackles (Quiscalus spp, Icterinae)1991In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 45, p. 608-621Article in journal (Refereed)
  • 23.
    Björklund, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Phenotypic variation in growth trajectories in finches1993In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 47, p. 1506-1514Article in journal (Refereed)
  • 24.
    Björklund, Mats
    et al.
    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 Genetics, Animal ecology.
    The stability of the G-matrix: The role of spatial heterogeneity2015In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 69, no 7, p. 1953-1958Article in journal (Refereed)
    Abstract [en]

    The temporal stability of the genetic variance-covariance matrix (G) has been discussed for a long time in the evolutionary literature. A common assumption in all studies, including empirical ones, is that spatial heterogeneity is minor such that the population can be represented by a single mean and variance. We use the well-established allocation-acquisition model to analyze the effect of relaxing of this assumption, simulating a case where the population is divided into patches with a variance in quality between patches. This variance can in turn differ between years. We found that changes in spatial variance in patch quality over years can make the G-matrix vary substantially over years and that the estimated genetic correlations, evolvability, and response to selection are different dependent on whether spatial heterogeneity is taken into account or not. This will have profound implications for our ability to predict evolutionary change and understanding of the evolutionary process.

  • 25.
    Björklund, Mats
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Merilä, Juha
    Baker, Alan J
    Historical demography and present day population structure of the Greenfinch (Carduelis chloris) - an analysis of mtDNA control-region sequences1997In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 51, p. 946-956Article in journal (Refereed)
  • 26.
    Bokma, F
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Bayesian estimation of speciation and extinction rates from (in)complete phylogenies2008In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 62, p. 2441-2445Article in journal (Refereed)
    Abstract [en]

    Speciation and extinction probabilities can be estimated from molecular phylogenies of extant species that are complete at the species level. Because only a fraction of published phylogenies is complete at the species level, methods have been developed to estimate speciation and extinction probabilities also from incomplete phylogenies. However, due to different estimation techniques, estimates from complete and incomplete phylogenies are difficult to compare statistically. Here I show with some examples how existing likelihood functions can be used to obtain Bayesian estimates of speciation and extinction probabilities, and how this approach is applied to both complete and incomplete phylogenies.

  • 27.
    Bokma, Folmer
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    van den Brink, Valentijn
    Stadler, Tanja
    Unexpectedly many extinct hominins2012In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 66, no 9, p. 2969-2974Article in journal (Refereed)
    Abstract [en]

    Recent studies indicate that Neanderthal and Denisova hominins may have been separate species, while debate continues on the status of Homo floresiensis. The decade-long debate between splitters, who recognize over 20 hominin species, and lumpers, who maintain that all these fossils belong to just a few lineages, illustrates that we do not know how many extinct hominin species to expect. Here, we present probability distributions for the number of speciation events and the number of contemporary species along a branch of a phylogeny. With estimates of hominin speciation and extincton rates, we then show that the expected total number of extinct hominin species is 8, but may be as high as 27. We also show that it is highly unlikely that three very recent species disappeared due to natural, background extinction. This may indicate that human-like remains are too easily considered distinct species. Otherwise, the evidence suggesting that Neanderthal and the Denisova hominin represent distinct species implies a recent wave of extinctions, ostensibly driven by the only survivor, H. sapiens.

  • 28.
    Bolund, Elisabeth
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Hayward, Adam
    Pettay, Jenni E.
    Lummaa, Virpi
    Effects of the demographic transition on the genetic variances and covariances of human life-history traits2015In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 69, no 3, p. 747-755Article in journal (Refereed)
    Abstract [en]

    The recent demographic transitions to lower mortality and fertility rates in most human societies have led to changes and even quick reversals in phenotypic selection pressures. This can only result in evolutionary change if the affected traits are heritable, but changes in environmental conditions may also lead to subsequent changes in the genetic variance and covariance (the G matrix) of traits. It currently remains unclear if there have been concomitant changes in the G matrix of life-history traits following the demographic transition. Using 300 years of genealogical data from Finland, we found that four key life-history traits were heritable both before and after the demographic transition. The estimated heritabilities allow a quantifiable genetic response to selection during both time periods, thus facilitating continued evolutionary change. Further, the G matrices remained largely stable but revealed a trend for an increased additive genetic variance and thus evolutionary potential of the population after the transition. Our results demonstrate the validity of predictions of evolutionary change in human populations even after the recent dramatic environmental change, and facilitate predictions of how our biology interacts with changing environments, with implications for global public health and demography.

  • 29.
    Boughman, Janette W.
    et al.
    Michigan State Univ, Dept Integrat Biol, E Lansing, MI 48824 USA..
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Synergistic selection between ecological niche and mate preference primes diversification2017In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 71, no 1, p. 6-22Article in journal (Refereed)
    Abstract [en]

    The ecological niche and mate preferences have independently been shown to be important for the process of speciation. Here, we articulate a novel mechanism by which ecological niche use and mate preference can be linked to promote speciation. The degree to which individual niches are narrow and clustered affects the strength of divergent natural selection and population splitting. Similarly, the degree to which individual mate preferences are narrow and clustered affects the strength of divergent sexual selection and assortative mating between diverging forms. This novel perspective is inspired by the literature on ecological niches; it also explores mate preferences and how they may contribute to speciation. Unlike much comparative work, we do not search for evolutionary patterns using proxies for adaptation and sexual selection, but rather we elucidate how ideas from niche theory relate to mate preference, and how this relationship can foster speciation. Recognizing that individual and population niches are conceptually and ecologically linked to individual and population mate preference functions will significantly increase our understanding of rapid evolutionary diversification in nature. It has potential to help solve the difficult challenge of testing the role of sexual selection in the speciation process. We also identify ecological factors that are likely to affect individual niche and individual mate preference in synergistic ways and as a consequence to promote speciation. The ecological niche an individual occupies can directly affect its mate preference. Clusters of individuals with narrow, differentiated niches are likely to have narrow, differentiated mate preference functions. Our approach integrates ecological and sexual selection research to further our understanding of diversification processes. Such integration may be necessary for progress because these processes seem inextricably linked in the natural world.

  • 30.
    Braga, Mariana P.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Araujo, Sabrina B. L.
    Agosta, Salvatore
    Brooks, Daniel
    Hoberg, Eric
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology.
    Boeger, Walter A.
    Host use dynamics in a heterogeneous fitness landscape generates oscillations in host range and diversification2018In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 72, no 9, p. 1773-1783Article in journal (Refereed)
    Abstract [en]

    Colonization of novel hosts is thought to play an important role in parasite diversification, yet little consensus has been achieved about the macroevolutionary consequences of changes in host use. Here, we offer a mechanistic basis for the origins of parasite diversity by simulating lineages evolved in silico. We describe an individual-based model in which (i) parasites undergo sexual reproduction limited by genetic proximity, (ii) hosts are uniformly distributed along a one-dimensional resource gradient, and (iii) host use is determined by the interaction between the phenotype of the parasite and a heterogeneous fitness landscape. We found two main effects of host use on the evolution of a parasite lineage. First, the colonization of a novel host allowed parasites to explore new areas of the resource space, increasing phenotypic and genotypic variation. Second, hosts produced heterogeneity in the parasite fitness landscape, which led to reproductive isolation and therefore, speciation. As a validation of the model, we analyzed empirical data from Nymphalidae butterflies and their host plants. We then assessed the number of hosts used by parasite lineages and the diversity of resources they encompass. In both simulated and empirical systems, host diversity emerged as the main predictor of parasite species richness.

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  • 31.
    Brengdahl, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Kimber, Christopher
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Maguire-Baxter, Jack
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Friberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Sex differences in life span: Females homozygous for the X chromosome do not suffer the shorter life span predicted by the unguarded X hypothesis2018In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 72, no 3, p. 568-577Article in journal (Refereed)
    Abstract [en]

    Life span differs between the sexes in many species. Three hypotheses to explain this interesting pattern have been proposed, involving different drivers: sexual selection, asymmetrical inheritance of cytoplasmic genomes, and hemizygosity of the X(Z) chromosome (the unguarded X hypothesis). Of these, the unguarded X has received the least experimental attention. This hypothesis suggests that the heterogametic sex suffers a shortened life span because recessive deleterious alleles on its single X(Z) chromosome are expressed unconditionally. In Drosophila melanogaster, the X chromosome is unusually large (approximate to 20% of the genome), providing a powerful model for evaluating theories involving the X. Here, we test the unguarded X hypothesis by forcing D. melanogaster females from a laboratory population to express recessive X-linked alleles to the same degree as males, using females exclusively made homozygous for the X chromosome. We find no evidence for reduced life span or egg-to-adult viability due to X homozygozity. In contrast, males and females homozygous for an autosome both suffer similar, significant reductions in those traits. The logic of the unguarded X hypothesis is indisputable, but our results suggest that the degree to which recessive deleterious X-linked alleles depress performance in the heterogametic sex appears too small to explain general sex differences in life span.

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  • 32.
    Budd, Graham
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Mann, Richard P.
    Univ Leeds, Sch Math, Dept Stat, Leeds LS2 9JT, W Yorkshire, England.
    History is written by the victors: The effect of the push of the past on the fossil record2018In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 72, no 11, p. 2276-2291Article in journal (Refereed)
    Abstract [en]

    Survivorship biases can generate remarkable apparent rate heterogeneities through time in otherwise homogeneous birth-death models of phylogenies. They are a potential explanation for many striking patterns seen in the fossil record and molecular phylogenies. One such bias is the "push of the past": clades that survived a substantial length of time are likely to have experienced a high rate of early diversification. This creates the illusion of a secular rate slow-down through time that is, rather, a reversion to the mean. An extra effect increasing early rates of lineage generation is also seen in large clades. These biases are important but relatively neglected influences on many aspects of diversification patterns in the fossil record and elsewhere, such as diversification spikes after mass extinctions and at the origins of clades; they also influence rates of fossilization, changes in rates of phenotypic evolution and even molecular clocks. These inevitable features of surviving and/or large clades should thus not be generalized to the diversification process as a whole without additional study of small and extinct clades, and raise questions about many of the traditional explanations of the patterns seen in the fossil record.

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  • 33.
    Burri, Reto
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Antoniazza, Sylvain
    Univ Lausanne, Biophore, Dept Ecol & Evolut, CH-1015 Lausanne, Switzerland.;Swiss Ornithol Inst, CH-6204 Sempach, Switzerland..
    Gaigher, Arnaud
    Univ Lausanne, Biophore, Dept Ecol & Evolut, Lab Conservat Biol, CH-1015 Lausanne, Switzerland..
    Ducrest, Anne-Lyse
    Univ Lausanne, Biophore, Dept Ecol & Evolut, CH-1015 Lausanne, Switzerland..
    Simon, Celine
    Univ Lausanne, Biophore, Dept Ecol & Evolut, CH-1015 Lausanne, Switzerland..
    Fumagalli, Luca
    Univ Lausanne, Biophore, Dept Ecol & Evolut, Lab Conservat Biol, CH-1015 Lausanne, Switzerland..
    Goudet, Jerome
    Univ Lausanne, Biophore, Dept Ecol & Evolut, CH-1015 Lausanne, Switzerland..
    Roulin, Alexandre
    Univ Lausanne, Biophore, Dept Ecol & Evolut, CH-1015 Lausanne, Switzerland..
    The genetic basis of color-related local adaptation in a ring-like colonization around the Mediterranean2016In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 70, no 1, p. 140-153Article in journal (Refereed)
    Abstract [en]

    Uncovering the genetic basis of phenotypic variation and the population history under which it established is key to understand the trajectories along which local adaptation evolves. Here, we investigated the genetic basis and evolutionary history of a clinal plumage color polymorphism in European barn owls (Tyto alba). Our results suggest that barn owls colonized the Western Palearctic in a ring-like manner around the Mediterranean and meet in secondary contact in Greece. Rufous coloration appears to be linked to a recently evolved nonsynonymous-derived variant of the melanocortin 1 receptor (MC1R) gene, which according to quantitative genetic analyses evolved under local adaptation during or following the colonization of Central Europe. Admixture patterns and linkage disequilibrium between the neutral genetic background and color found exclusively within the secondary contact zone suggest limited introgression at secondary contact. These results from a system reminiscent of ring species provide a striking example of how local adaptation can evolve from derived genetic variation.

  • 34.
    Carlsson-Graner, Ulla
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Thrall, Peter H.
    Host resistance and pathogen infectivity in host populations with varying connectivity2015In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 69, no 4, p. 926-938Article in journal (Refereed)
    Abstract [en]

    Theory predicts that hosts and pathogens will evolve higher resistance and aggressiveness in systems where populations are spatially connected than in situations in which populations are isolated and dispersal is more local. In a large cross-inoculation experiment we surveyed patterns of host resistance and pathogen infectivity in anther-smut diseased Viscaria alpina populations from three contrasting areas where populations range from continuous, through patchy but spatially connected to highly isolated demes. In agreement with theory, isolated populations of V. alpina were more susceptible on average than either patchily distributed or continuous populations. While increased dispersal in connected systems increases disease spread, it may also increase host gene flow and the potential for greater host resistance to evolve. In the Viscaria-Microbotryum system, pathogen infectivity mirrored patterns of host resistance with strains from the isolated populations being the least infective and strains from the more resistant continuous populations being the most infective on average, suggesting that high resistance selects for high infectivity. To our knowledge this study is the first to characterize the impacts of varying spatial connectivity on patterns of host resistance and pathogen infectivity in a natural system.

  • 35.
    Caruso, Christina M.
    et al.
    Univ Guelph, Dept Integrat Biol, Guelph, ON, Canada.
    Eisen, Katherine E.
    Univ Guelph, Dept Integrat Biol, Guelph, ON, Canada; Cornell Univ, Dept Ecol & Evolutionary Biol, Ithaca, NY, USA.
    Martin, Ryan A.
    Case Western Reserve Univ, Dept Biol, Cleveland, OH, USA.
    Sletvold, Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    A meta-analysis of the agents of selection on floral traits2019In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 73, no 1, p. 4-14Article in journal (Refereed)
    Abstract [en]

    Floral traits are hypothesized to evolve primarily in response to selection by pollinators. However, selection can also be mediated by other environmental factors. To understand the relative importance of pollinator-mediated selection and its variation among trait and pollinator types, we analyzed directional selection gradients on floral traits from experiments that manipulated the environment to identify agents of selection. Pollinator-mediated selection was stronger than selection by other biotic factors (e.g., herbivores), but similar in strength to selection by abiotic factors (e.g., soil water), providing partial support for the hypothesis that floral traits evolve primarily in response to pollinators. Pollinator-mediated selection was stronger on pollination efficiency traits than on other trait types, as expected if efficiency traits affect fitness via interactions with pollinators, but other trait types also affect fitness via other environmental factors. In addition to varying among trait types, pollinator-mediated selection varied among pollinator taxa: selection was stronger when bees, long-tongued flies, or birds were the primary visitors than when the primary visitors were Lepidoptera or multiple animal taxa. Finally, reducing pollinator access to flowers had a relatively small effect on selection on floral traits, suggesting that anthropogenic declines in pollinator populations would initially have modest effects on floral evolution.

  • 36. Cayetano, Luis
    et al.
    Maklakov, Alexei A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Brooks, Robert C.
    Bonduriansky, Russell
    Evolution of male and female genitalia following release from sexual selection2011In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, no 8, p. 2171-2183Article in journal (Refereed)
    Abstract [en]

    Despite the key functions of the genitalia in sexual interactions and fertilization, the role of sexual selection and conflict in shaping genital traits remains poorly understood. Seed beetle (Callosobruchus maculatus) males possess spines on the intromittent organ, and females possess a thickened reproductive tract wall that also bears spines. We investigated the role of sexual selection and conflict by imposing monogamous mating on eight replicate populations of this naturally polygamous insect, while maintaining eight other populations under polygamy. To establish whether responses to mating system manipulation were robust to ecological context, we simultaneously manipulated life-history selection (early/late reproduction). Over 18-21 generations, male genital spines evolved relatively reduced length in large males (i.e., shallower static allometry) in monogamous populations. Two nonintromittent male genital appendages also evolved in response to the interaction of mating system and ecology. In contrast, no detectable evolution occurred in female genitalia, consistent with the expectation of a delayed response in defensive traits. Our results support a sexually antagonistic role for the male genital spines, and demonstrate the evolution of static allometry in response to variation in sexual selection opportunity. We argue that further advances in the study of genital coevolution will require a much more detailed understanding of the functions of male and female genital traits.

  • 37.
    Collet, Julie M.
    et al.
    UCL, Res Dept Genet Evolut & Environm, London, England.;Univ Queensland, Sch Biol Sci, St Lucia, Qld, Australia..
    Fuentes, Sara
    UCL, Res Dept Genet Evolut & Environm, London, England..
    Hesketh, Jack
    UCL, Res Dept Genet Evolut & Environm, London, England..
    Hill, Mark S.
    UCL, Res Dept Genet Evolut & Environm, London, England..
    Innocenti, Paolo
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Morrow, Edward H.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology. Univ Sussex, Sch Life Sci, Brighton, E Sussex, England..
    Fowler, Kevin
    UCL, Res Dept Genet Evolut & Environm, London, England..
    Reuter, Max
    UCL, Res Dept Genet Evolut & Environm, London, England..
    Rapid evolution of the intersexual genetic correlation for fitness in Drosophila melanogaster2016In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 70, no 4, p. 781-795Article in journal (Refereed)
    Abstract [en]

    Sexual antagonism (SA) arises when male and female phenotypes are under opposing selection, yet genetically correlated. Until resolved, antagonism limits evolution toward optimal sex-specific phenotypes. Despite its importance for sex-specific adaptation and existing theory, the dynamics of SA resolution are not well understood empirically. Here, we present data from Drosophila melanogaster, compatible with a resolution of SA. We compared two independent replicates of the LHM population in which SA had previously been described. Both had been maintained under identical, controlled conditions, and separated for around 200 generations. Although heritabilities of male and female fitness were similar, the intersexual genetic correlation differed significantly, being negative in one replicate (indicating SA) but close to zero in the other. Using population sequencing, we show that phenotypic differences were associated with population divergence in allele frequencies at nonrandom loci across the genome. Large frequency changes were more prevalent in the population without SA and were enriched at loci mapping to genes previously shown to have sexually antagonistic relationships between expression and fitness. Our data suggest that rapid evolution toward SA resolution has occurred in one of the populations and open avenues toward studying the genetics of SA and its resolution.

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  • 38.
    Corl, Ammon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Ellegren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    The genomic signature of sexual selection in the genetic diversity of the sex chromosomes and autosomes2012In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 66, no 7, p. 2138-2149Article in journal (Refereed)
    Abstract [en]

    Genomic levels of variation can help reveal the selective and demographic forces that have affected a species during its history. The relative amount of genetic diversity observed on the sex chromosomes as compared to the autosomes is predicted to differ among monogamous and polygynous species. Many species show departures from the expectation for monogamy, but it can be difficult to conclude that this pattern results from variation in mating system because forces other than sexual selection can act upon sex chromosome genetic diversity. As a critical test of the role of mating system, we compared levels of genetic diversity on the Z chromosome and autosomes of phylogenetically independent pairs of shorebirds that differed in their mating systems. We found general support for sexual selection shaping sex chromosome diversity because most polygynous species showed relatively reduced genetic variation on their Z chromosomes as compared to monogamous species. Differences in levels of genetic diversity between the sex chromosomes and autosomes may therefore contribute to understanding the long-term history of sexual selection experienced by a species.

  • 39.
    Cramer, Emily R. A.
    et al.
    Univ Oslo, Nat Hist Museum, N-0318 Oslo, Norway.;Smithsonian Migratory Bird Ctr, POB 37012 MRC5503, Washington, DC 20008 USA.;Cornell Lab Ornithol, Ithaca, NY 14850 USA..
    Ålund, Murielle
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    McFarlane, S. Eryn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Johnsen, Arild
    Univ Oslo, Nat Hist Museum, N-0318 Oslo, Norway..
    Qvarnström, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Females discriminate against heterospecific sperm in a natural hybrid zone2016In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 70, no 8, p. 1844-1855Article in journal (Refereed)
    Abstract [en]

    When hybridization is maladaptive, species-specific mate preferences are selectively favored, but low mate availability may constrain species-assortative pairing. Females paired to heterospecifics may then benefit by copulating with multiple males and subsequently favoring sperm of conspecifics. Whether such mechanisms for biasing paternity toward conspecifics act as important reproductive barriers in socially monogamous vertebrate species remains to be determined. We use a combination of long-term breeding records from a natural hybrid zone between collared and pied flycatchers (Ficedula albicollis and F. hypoleuca), and an in vitro experiment comparing conspecific and heterospecific sperm performance in female reproductive tract fluid, to evaluate the potential significance of female cryptic choice. We show that the females most at risk of hybridizing (pied flycatchers) frequently copulate with multiple males and are able to inhibit heterospecific sperm performance. The negative effect on heterospecific sperm performance was strongest in pied flycatcher females that were most likely to have been previously exposed to collared flycatcher sperm. We thus demonstrate that a reproductive barrier acts after copulation but before fertilization in a socially monogamous vertebrate. While the evolutionary history of this barrier is unknown, our results imply that there is opportunity for it to be accentuated via a reinforcement-like process.

  • 40.
    de Boer, Raïssa A.
    et al.
    University of Antwerp, Belgium.
    Eens, Marcel
    Fransen, Erik
    Müller, Wendt
    Hatching asynchrony aggravates inbreeding depression in a songbird (Serinus canaria): An inbreeding–environment interaction2015In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 69, no 4, p. 1063-1068Article in journal (Refereed)
    Abstract [en]

    Understanding how the intensity of inbreeding depression is influenced by stressful environmental conditions is an important area of enquiry in various fields of biology. In birds, environmental stress during early development is often related to hatching asynchrony; differences in age, and thus size, impose a gradient in conditions ranging from benign (first hatched chick) to harsh (last hatched chick). Here, we compared the effect of hatching order on growth rate in inbred (parents are full siblings) and outbred (parents are unrelated) canary chicks (Serinus canaria). We found that inbreeding depression was more severe under more stressful conditions, being most evident in later hatched chicks. Thus, consideration of inbreeding‐environment interactions is of vital importance for our understanding of the biological significance of inbreeding depression and hatching asynchrony. The latter is particularly relevant given that hatching asynchrony is a widespread phenomenon, occurring in many bird species. The exact causes of the observed inbreeding‐environment interaction are as yet unknown, but may be related to a decrease in maternal investment in egg contents with laying position (i.e. prehatching environment), or to performance of the chicks during sibling competition and/or their resilience to food shortage (i.e. posthatching environment).

  • 41.
    Dordevic, Mirko
    et al.
    Univ Belgrade, Inst Biol Res, Dept Evolutionary Biol, Despota Stefana Blvd 142, Belgrade 11060, Serbia..
    Stojkovic, Biljana
    Univ Belgrade, Inst Biol Res, Dept Evolutionary Biol, Despota Stefana Blvd 142, Belgrade 11060, Serbia.;Univ Belgrade, Fac Biol, Inst Zool, Studentskitrg 16, Belgrade 11000, Serbia..
    Savkovic, Uros
    Univ Belgrade, Inst Biol Res, Dept Evolutionary Biol, Despota Stefana Blvd 142, Belgrade 11060, Serbia..
    Immonen, Elina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Tucic, Nikola
    Univ Belgrade, Inst Biol Res, Dept Evolutionary Biol, Despota Stefana Blvd 142, Belgrade 11060, Serbia..
    Lazarevic, Jelica
    Univ Belgrade, Inst Biol Res, Dept Insect Physiol & Biochem, Despota Stefana Blvd 142, Belgrade 11060, Serbia..
    Arnqvist, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Sex-specific mitonuclear epistasis and the evolution of mitochondrial bioenergetics, ageing, and life history in seed beetles2017In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 71, no 2, p. 274-288Article in journal (Refereed)
    Abstract [en]

    The role of mitochondrial DNA for the evolution of life-history traits remains debated. We examined mitonuclear effects on the activity of the multisubunit complex of the electron transport chain (ETC) involved in oxidative phosphorylation (OXPHOS) across lines of the seed beetle Acanthoscelides obtectus selected for a short (E) or a long (L) life for more than >160 generations. We constructed and phenotyped mitonuclear introgression lines, which allowed us to assess the independent effects of the evolutionary history of the nuclear and the mitochondrial genome. The nuclear genome was responsible for the largest share of divergence seen in ageing. However, the mitochondrial genome also had sizeable effects, which were sex-specific and expressed primarily as epistatic interactions with the nuclear genome. The effects of mitonuclear disruption were largely consistent with mitonuclear coadaptation. Variation in ETC activity explained a large proportion of variance in ageing and life-history traits and this multivariate relationship differed somewhat between the sexes. In conclusion, mitonuclear epistasis has played an important role in the laboratory evolution of ETC complex activity, ageing, and life histories and these are closely associated. The mitonuclear architecture of evolved differences in life-history traits and mitochondrial bioenergetics was sex-specific.

  • 42.
    Dowling, Damian K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Chávez-Abiega, Katia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Arnqvist, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Temperature-specific outcomes of cytoplasmic-nuclear interactions on egg-to-adult development time in seed beetles2007In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 61, no 1, p. 194-201Article in journal (Refereed)
    Abstract [en]

    The integration of the mitochondrial and nuclear genomes coordinates cellular energy production and is fundamental to life among eukaryotes. Therefore, there is potential for strong selection to shape the interactions between the two genomes. Several studies have now demonstrated that epistatic interactions between cytoplasmic and nuclear genes for fitness can occur both at a "within" and "across" population level. Genotype-by-environment interactions are common for traits that are encoded by nuclear genes, but the effects of environmental heterogeneity on traits that are partly encoded by cytoplasmic genes have received little attention despite the fact that there are reasons to believe that phenotypic effects of cytoplasmic genetic variation may often be environment specific. Consequently, the importance of environmental heterogeneity to the outcomes of cyto-nuclear fitness interactions and to the maintenance of mitochondrial polymorphism is unclear. Here, we assess the influence of temperature on cyto-nuclear effects on egg-to-adult development time in seed beetles (Callosobruchus maculatus). We employed an "across-population" design, sourcing beetles from five distinct populations and using backcrossing to create orthogonal combinations of distinct introgression lines, fixed for their cytoplasmic and nuclear lineages. We then assayed development times at two different temperatures and found sizeable cyto-nuclear effects in general, as well as temperature- and block-specific cyto-nuclear effects. These results demonstrate that environmental factors such as temperature do exert selection on cytoplasmic genes by favoring specific cyto-nuclear genetic combinations, and are consistent with the suggestion that complex genotype-by-environment interactions may promote the maintenance of polymorphism in mitochondrial genes.

  • 43.
    Dynesius, Mats
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Persistence of within-species lineages: a neglected control of speciation rates2014In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 68, no 4, p. 923-934Article in journal (Refereed)
    Abstract [en]

    We present a framework distinguishing three principal controls of speciation rate: rate of splitting, level of persistence, and length of speciation duration. We contend that discussions on diversification become clearer in the light of this framework, because speciation rate variation could be attributed to any of these controls. In particular, we claim that the role of persistence of within-species lineages in controlling speciation rates has been greatly underappreciated. More emphasis on the persistence control would change expectations of the role of several biological traits and environmental factors, because they may drive speciationrate in one direction through the persistence control and in the opposite direction through the other two controls. Traits and environments have been little studied regarding their influence on speciation rate through the persistence control, with climatic fluctuations being a relatively well-studied exception. Considering the recent advances in genomic and phylogenetic analysis, we think that the time is ripe for applying the framework in empirical research. Variation among clades and areas (and thus among traits and environments) in the importance of the three rate controls could be addressed for example by dating splitting events, detecting within-species lineages, and scanning genomes for evidence of divergent selection.

  • 44.
    Eckerström-Liedholm, Simon
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Sowersby, Will
    Stockholm University, Faculty of Science, Department of Zoology.
    Gonzalez-Voyer, Alejandro
    Stockholm University, Faculty of Science, Department of Zoology. Universidad Nacional Autónoma de México, Mexico.
    Rogell, Björn
    Stockholm University, Faculty of Science, Department of Zoology.
    Time-limited environments affect the evolution of egg-body size allometry2017In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 71, no 7, p. 1900-1910Article in journal (Refereed)
    Abstract [en]

    Initial offspring size is a fundamental component of absolute growth rate, where large offspring will reach a given adult body size faster than smaller offspring. Yet, our knowledge regarding the coevolution between offspring and adult size is limited. In time-constrained environments, organisms need to reproduce at a high rate and reach a reproductive size quickly. To rapidly attain a large adult body size, we hypothesize that, in seasonal habitats, large species are bound to having a large initial size, and consequently, the evolution of egg size will be tightly matched to that of body size, compared to less time-limited systems. We tested this hypothesis in killifishes, and found a significantly steeper allometric relationship between egg and body sizes in annual, compared to nonannual species. We also found higher rates of evolution of egg and body size in annual compared to nonannual species. Our results suggest that time-constrained environments impose strong selection on rapidly reaching a species-specific body size, and reproduce at a high rate, which in turn imposes constraints on the evolution of egg sizes. In combination, these distinct selection pressures result in different relationships between egg and body size among species in time-constrained versus permanent habitats.

  • 45.
    Eckerström-Liedholm, Simon
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Sowersby, Will
    Stockholm University, Faculty of Science, Department of Zoology.
    Morozov, Sergey
    van der Bijl, Wouter
    Stockholm University, Faculty of Science, Department of Zoology. University of British Columbia, Canada.
    Rowiński, Piotr K.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gonzalez-Voyer, Alejandro
    Stockholm University, Faculty of Science, Department of Zoology. Universidad Nacional Autónoma de México, Mexico.
    Rogell, Björn
    Stockholm University, Faculty of Science, Department of Zoology.
    Macroevolutionary evidence suggests trait-dependent coevolution between behavior and life-history2019In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 73, no 11, p. 2312-2323Article in journal (Refereed)
    Abstract [en]

    Species with fast life-histories typically prioritize current over future reproductive events, compared to species with slow life-histories. These species therefore require greater energetic input into reproduction, and also likely have less time to realize their reproductive potential. Hence, behaviors that increase access to both resources and mating opportunities, at a cost of increased mortality risk, could coevolve with the pace of life-history. However, whether this prediction holds across species, remains untested under standardized conditions. Here, we test how risky behaviors, which facilitate access to resources and mating opportunities (i.e., activity, boldness, and aggression), along with metabolic rate, coevolve with the pace of life-history across 20 species of killifish that present remarkable divergences in the pace of life-history. We found a positive association between the pace of life-history and aggression, but interestingly not with other behavioral traits or metabolic rate. Aggression is linked to interference competition, and in killifishes is often employed to secure mates, while activity and boldness are more relevant for exploiting energetic resources. Our results suggest that the trade-off between current and future reproduction plays a more prominent role in shaping mating behavior, while behaviors related to energy acquisition may be influenced by ecological factors.

  • 46.
    Edelaar, Pim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Siepielski, Adam M.
    Clobert, Jean
    Matching habitat choice causes directed gene flow: A neglected dimension in evolution and ecology2008In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 62, p. 2462-2472Article in journal (Refereed)
    Abstract [en]

    Gene flow among populations is typically thought to be antagonistic to population differentiation and local adaptation. However,this assumes that dispersing individuals disperse randomly with respect to their ability to use the environment. Yet dispersingindividuals often sample and compare environments and settle in those environments that best match their phenotype, causingdirected gene flow, which can in fact promote population differentiation and adaptation. We refer to this process as “matchinghabitat choice.” Although this process has been acknowledged by several researchers, no synthesis or perspective on its potentiallywidespread importance exists. Here we synthesize empirical and theoretical studies, and offer a new perspective that matchinghabitat choice can have significant effects on important and controversial topics. We discuss the potential implications of matchinghabitat choice for the degree and rate of local adaptation, the evolution of niche width, adaptive peak shifts, speciation in thepresence of gene flow, and on our view and interpretation of measures of natural selection. Because of its potential importance forsuch a wide range of topics, we call for heightened empirical and theoretical attention for this neglected dimension in evolutionaryand ecological studies.

  • 47.
    Ellegren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    A selection model of molecular evolution incorporating the effective population size.2009In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 63, no 2, p. 301-305Article in journal (Refereed)
  • 48. Engen, Steinar
    et al.
    Ringsby, Thor Harald
    Saether, Bernt-Erik
    Lande, Russell
    Jensen, Henrik
    Lillegård, Magnar
    Ellegren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Evolutionary Biology.
    Effective size of fluctuating populations with two sexes and overlapping generations2007In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 61, no 8, p. 1873-1885Article in journal (Refereed)
    Abstract [en]

    We derive formulas that can be applied to estimate the effective population size N(e) for organisms with two sexes reproducing once a year and having constant adult mean vital rates independent of age. Temporal fluctuations in population size are generated by demographic and environmental stochasticity. For populations with even sex ratio at birth, no deterministic population growth and identical mean vital rates for both sexes, the key parameter determining N(e) is simply the mean value of the demographic variance for males and females considered separately. In this case Crow and Kimura's generalization of Wright's formula for N(e) with two sexes, in terms of the effective population sizes for each sex, is applicable even for fluctuating populations with different stochasticity in vital rates for males and females. If the mean vital rates are different for the sexes then a simple linear combination of the demographic variances determines N(e), further extending Wright's formula. For long-lived species an expression is derived for N(e) involving the generation times for both sexes. In the general case with nonzero population growth and uneven sex ratio of newborns, we use the model to investigate numerically the effects of different population parameters on N(e). We also estimate the ratio of effective to actual population size in six populations of house sparrows on islands off the coast of northern Norway. This ratio showed large interisland variation because of demographic differences among the populations. Finally, we calculate how N(e) in a growing house sparrow population will change over time.

  • 49.
    Eroukhmanoff, Fabrice
    et al.
    Section for Animal Ecology, Ecology Building, Lund University, Lund, Sweden.
    Hargeby, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Svensson, Erik I.
    Section for Animal Ecology, Ecology Building, Lund University, Lund, Sweden.
    THE ROLE OF DIFFERENT REPRODUCTIVE BARRIERS DURING PHENOTYPIC DIVERGENCE OF ISOPOD ECOTYPES2011In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, no 9, p. 2631-2640Article in journal (Refereed)
    Abstract [en]

    The question of how diverging populations become separate species by restraining gene flow is a central issue in evolutionary biology. Assortative mating might emerge early during adaptive divergence, but the role of other types of reproductive barriers such as migration modification have recently received increased attention. We demonstrate that two recently diverged ecotypes of a freshwater isopod (Asellus aquaticus) have rapidly developed premating isolation, and this isolation barrier has emerged independently and in parallel in two south Swedish lakes. This is consistent with ecological speciation theory, which predicts that reproductive isolation arises as a byproduct of ecological divergence. We also find that in one of these lakes, habitat choice acts as the main barrier to gene flow. These observations and experimental results suggest that migration modification might be as important as assortative mating in the early stages of ecological speciation. Simulations suggest that the joint action of these two isolating barriers is likely to greatly facilitate adaptive divergence, compared to if each barrier was acting alone.

  • 50. Evans, Simon R.
    et al.
    Gustafsson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Sheldon, Ben C.
    Divergent Patterns of Age-dependence in Ornamental and Reproductive Traits in the Collared Flycatcher2011In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, no 6, p. 1623-1636Article in journal (Refereed)
    Abstract [en]

    Sexual ornaments are predicted to honestly signal individual condition. We might therefore expect ornament expression to show a senescent decline, in parallel with late-life deterioration of other characters. Conversely, life-history theory predicts the reduced residual reproductive value of older individuals will favor increased investment in sexually attractive traits. Using a 25-year dataset of more than 5000 records of breeding collared flycatchers (Ficedula albicollis) of known age, we quantify cross-sectional patterns of age-dependence in ornamental plumage traits and report long-term declines in expression that mask highly significant positive age-dependency. We partition this population-level age-dependency into its between- and within-individual components and show expression of ornamental white plumage patches exhibits within-individual increases with age in both sexes, consistent with life-history theory. For males, ornament expression also covaries with life span, such that, within a cohort, ornamentation indicates survival. Finally, we compared longitudinal age-dependency of reproductive traits and ornamental traits in both sexes, to assess whether these two trait types exhibit similar age-dependency. These analyses revealed contrasting patterns: reproductive traits showed within-individual declines in late-life females consistent with senescence; ornamental traits showed the opposite pattern in both males and females. Hence, our results for both sexes suggest that age-dependent ornament expression is consistent with life-history models of optimal signaling and, unlike reproductive traits, proof against senescence.

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