| 1. |
- Albertsen, Elena, et al.
(författare)
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Using ecological context to interpret spatiotemporal variation in natural selection
- 2021
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 75:2, s. 294-309
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Tidskriftsartikel (refereegranskat)abstract
- Spatiotemporal variation in natural selection is expected, but difficult to estimate. Pollinator-mediated selection on floral traits provides a good system for understanding and linking variation in selection to differences in ecological context. We studied pollinator-mediated selection in five populations of Dalechampia scandens (Euphorbiaceae) in Costa Rica and Mexico. Using a nonlinear path-analytical approach, we assessed several functional components of selection, and linked variation in pollinator-mediated selection across time and space to variation in pollinator assemblages. After correcting for estimation error, we detected moderate variation in net selection on two out of four blossom traits. Both the opportunity for selection and the mean strength of selection decreased with increasing reliability of cross-pollination. Selection for pollinator attraction was consistently positive and stronger on advertisement than reward traits. Selection on traits affecting pollen transfer from the pollinator to the stigmas was strong only when cross-pollination was unreliable and there was a mismatch between pollinator and blossom size. These results illustrate how consideration of trait function and ecological context can facilitate both the detection and the causal understanding of spatiotemporal variation in natural selection.
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| 2. |
- Bartoszek, Krzysztof, et al.
(författare)
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Analytical advances alleviate model misspecification in non-Brownian multivariate comparative methods
- 2023
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Ingår i: Evolution. - : OXFORD UNIV PRESS. - 0014-3820 .- 1558-5646.
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Tidskriftsartikel (refereegranskat)abstract
- Adams and Collyer argue that contemporary multivariate (Gaussian) phylogenetic comparative methods are prone to favouring more complex models of evolution and sometimes rotation invariance can be an issue. Here we dissect the concept of rotation invariance and point out that, depending on the understanding, this can be an issue with any method that relies on numerical instead of analytical estimation approaches. We relate this to the ongoing discussion concerning phylogenetic principal component analysis. Contrary to what Adams and Collyer found, we do not observe a bias against the simpler Brownian motion process in simulations when we use the new, improved, likelihood evaluation algorithm employed by mvSLOUCH, which allows for studying much larger phylogenies and more complex model setups.
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| 3. |
- Bliard, Louis, et al.
(författare)
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Family living and cooperative breeding in birds are associated with the number of avian predators
- 2024
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Ingår i: EVOLUTION. - 0014-3820 .- 1558-5646.
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Tidskriftsartikel (refereegranskat)abstract
- Cooperative breeding occurs when individuals contribute parental care to offspring that are not their own. Numerous intra- and interspecific studies have aimed to explain the evolution of this behavior. Recent comparative work suggests that family living (i.e., when offspring remain with their parents beyond independence) is a critical stepping stone in the evolution of cooperative breeding. Thus, it is key to understand the factors that facilitate the evolution of family living. Within-species studies suggest that protection from predators is a critical function of group living, through both passive benefits such as dilution effects and active benefits such as prosocial antipredator behaviors in family groups. However, the association between predation risk and the formation and prevalence of family groups and cooperative breeding remains untested globally. Here, we use phylogenetic comparative analyses including 2,984 bird species to show that family living and cooperative breeding are associated with increased occurrence of avian predators. These cross-species findings lend support to previous suggestions based on intraspecific studies that social benefits of family living, such as protection against predation, could favor the evolution of delayed dispersal and cooperative breeding.
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| 4. |
- Boyer, Loreleï, et al.
(författare)
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Asexual male production by ZW recombination inArtemia parthenogenetica
- 2022
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Ingår i: Evolution. - : Oxford University Press (OUP). - 0014-3820 .- 1558-5646. ; 77:1, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- In some asexual species, parthenogenetic females occasionally produce males, which may strongly affect the evolution and maintenance of asexuality if they cross with related sexuals and transmit genes causing asexuality to their offspring (“contagious parthenogenesis”). How these males arise in the first place has remained enigmatic, especially in species with sex chromosomes. Here, we test the hypothesis that rare, asexually produced males of the crustacean Artemia parthenogenetica are produced by recombination between the Z and W sex chromosomes during non-clonal parthenogenesis, resulting in ZZ males through loss of heterozygosity at the sex determination locus. We used RAD-sequencing to compare asexual mothers with their male and female offspring. Markers on several sex-chromosome scaffolds indeed lost heterozygosity in all male but no female offspring, suggesting that they correspond to the sex-determining region. Other sex-chromosome scaffolds lost heterozygosity in only a part of the male offspring, consistent with recombination occurring at a variable location. Alternative hypotheses for the production of these males (such as partial or total hemizygosity of the Z) could be excluded. Rare males are thus produced because recombination is not entirely suppressed during parthenogenesis in A. parthenogenetica. This finding may contribute to explaining the maintenance of recombination in these asexuals.
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| 5. |
- Butlin, Roger, 1955, et al.
(författare)
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Homage to Felsenstein 1981, or why are there so few/many species?
- 2021
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 75:5, s. 978-988
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Tidskriftsartikel (refereegranskat)abstract
- If there are no constraints on the process of speciation, then the number of species might be expected to match the number of available niches and this number might be indefinitely large. One possible constraint is the opportunity for allopatric divergence. In 1981, Felsenstein used a simple and elegant model to ask if there might also be genetic constraints. He showed that progress towards speciation could be described by the build-up of linkage disequilibrium among divergently selected loci and between these loci and those contributing to other forms of reproductive isolation. Therefore, speciation is opposed by recombination, because it tends to break down linkage disequilibria. Felsenstein then introduced a crucial distinction between "two-allele" models, which are subject to this effect, and "one-allele" models, which are free from the recombination constraint. These fundamentally important insights have been the foundation for both empirical and theoretical studies of speciation ever since.
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| 6. |
- Celorio-Mancera, Maria de la Paz, et al.
(författare)
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Larval transcriptomes reflect the evolutionary history of plant-insect associations
- 2023
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Ingår i: Evolution. - : Oxford University Press (OUP). - 0014-3820 .- 1558-5646. ; 77:2, s. 519-533
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we investigated whether patterns of gene expression in larvae feeding on different plants can explain important aspects of the evolution of insect-plant associations, such as phylogenetic conservatism of host use and re-colonization of ancestral hosts that have been lost from the host repertoire. To this end, we performed a phylogenetically informed study comparing the transcriptomes of 4 nymphalid butterfly species in Polygonia and the closely related genus Nymphalis. Larvae were reared on Urtica dioica, Salix spp., and Ribes spp. Plant-specific gene expression was found to be similar across butterfly species, even in the case of host plants that are no longer used by two of the butterfly species. These results suggest that plant-specific transcriptomes can be robust over evolutionary time. We propose that adaptations to particular larval food plants can profitably be understood as an evolved set of modules of co-expressed genes, promoting conservatism in host use and facilitating re-colonization. Moreover, we speculate that the degree of overlap between plant-specific transcriptomes may correlate with the strength of trade-offs between plants as resources and hence to the probability of colonizing hosts and complete host shifts.
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| 7. |
- Chase, Madeline A., et al.
(författare)
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Positive selection plays a major role in shaping signatures of differentiation across the genomic landscape of two independent Ficedula flycatcher species pairs
- 2021
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 75:9, s. 2179-2196
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Tidskriftsartikel (refereegranskat)abstract
- A current debate within population genomics surrounds the relevance of patterns of genomic differentiation between closely related species for our understanding of adaptation and speciation. Mounting evidence across many taxa suggests that the same genomic regions repeatedly develop elevated differentiation in independent species pairs. These regions often coincide with high gene density and/or low recombination, leading to the hypothesis that the genomic differentiation landscape mostly reflects a history of background selection, and reveals little about adaptation or speciation. A comparative genomics approach with multiple independent species pairs at a timescale where gene flow and ILS are negligible permits investigating whether different evolutionary processes are responsible for generating lineage-specific versus shared patterns of species differentiation. We use whole-genome resequencing data of 195 individuals from four Ficedula flycatcher species comprising two independent species pairs: collared and pied flycatchers, and red-breasted and taiga flycatchers. We found that both shared and lineage-specific FST peaks could partially be explained by selective sweeps, with recurrent selection likely to underlie shared signatures of selection, whereas indirect evidence supports a role of recombination landscape evolution in driving lineage-specific signatures of selection. This work therefore provides evidence for an interplay of positive selection and recombination to genomic landscape evolution.
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| 8. |
- Clo, Josselin, et al.
(författare)
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Genetics of quantitative traits with dominance under stabilizing and directional selection in partially selfing species
- 2021
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 75:8, s. 1920-1935
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Tidskriftsartikel (refereegranskat)abstract
- Recurrent self-fertilization is thought to lead to reduced adaptive potential by decreasing the genetic diversity of populations, thus leading selfing lineages down an evolutionary “blind alley.” Although well supported theoretically, empirical support for reduced adaptability in selfing species is limited. One limitation of classical theoretical models is that they assume pure additivity of the fitness-related traits that are under stabilizing selection, despite ample evidence that quantitative traits are subject to dominance. Here, we relax this assumption and explore the effect of dominance on a fitness-related trait under stabilizing selection for populations that differ in selfing rates. By decomposing the genetic variance into additional components specific to inbred populations, we show that dominance components can explain a substantial part of the genetic variance of inbred populations. We also show that ignoring these components leads to an upward bias in the predicted response to selection. Finally, we show that when considering the effect of dominance, the short-term evolutionary potential of populations remains comparable across the entire gradient in outcrossing rates, and genetic associations can even make selfing populations more evolvable on the longer term, reconciling theoretical, and empirical results.
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| 9. |
- Davies, Natasha, et al.
(författare)
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Evidence for stronger sexual selection in males than in females using an adapted method of Bateman's classic study of Drosophila melanogaster
- 2023
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Ingår i: Evolution. - : Oxford University Press. - 0014-3820 .- 1558-5646. ; 77:11, s. 2420-2430
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Tidskriftsartikel (refereegranskat)abstract
- Bateman's principles, originally a test of Darwin's theoretical ideas, have since become fundamental to sexual selection theory and vital to contextualizing the role of anisogamy in sex differences of precopulatory sexual selection. Despite this, Bateman's principles have received substantial criticism, and researchers have highlighted both statistical and methodological errors, suggesting that Bateman's original experiment contains too much sampling bias for there to be any evidence of sexual selection. This study uses Bateman's original method as a template, accounting for two fundamental flaws in his original experiments, (a) viability effects and (b) a lack of mating behavior observation. Experimental populations of Drosophila melanogaster consisted of wild-type focal individuals and nonfocal individuals established by backcrossing the brown eye (bw-) eye-color marker-thereby avoiding viability effects. Mating assays included direct observation of mating behavior and total number of offspring, to obtain measures of mating success, reproductive success, and standardized variance measures based on Bateman's principles. The results provide observational support for Bateman's principles, particularly that (a) males had significantly more variation in number of mates compared with females and (b) males had significantly more individual variation in total number of offspring. We also find a significantly steeper Bateman gradient for males compared to females, suggesting that sexual selection is operating more intensely in males. However, female remating was limited, providing the opportunity for future study to further explore female reproductive success in correlation with higher levels of remating.
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| 10. |
- De Lisle, Stephen P., et al.
(författare)
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Interacting phenotypes and the coevolutionary process : Interspecific indirect genetic effects alter coevolutionary dynamics
- 2022
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 76:3, s. 429-444
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Tidskriftsartikel (refereegranskat)abstract
- Coevolution occurs when species interact to influence one another's fitness, resulting in reciprocal evolutionary change. In many coevolving lineages, trait expression in one species is modified by the genotypes and phenotypes of the other, forming feedback loops reminiscent of models of intraspecific social evolution. Here, we adapt the theory of within-species social evolution, characterized by indirect genetic effects and social selection imposed by interacting individuals, to the case of interspecific interactions. In a trait-based model, we derive general expressions for multivariate evolutionary change in two species and the expected between-species covariance in evolutionary change when selection varies across space. We show that reciprocal interspecific indirect genetic effects can dominate the coevolutionary process and drive patterns of correlated evolution beyond what is expected from direct selection alone. In extreme cases, interspecific indirect genetic effects can lead to coevolution when selection does not covary between species or even when one species lacks genetic variance. Moreover, our model indicates that interspecific indirect genetic effects may interact in complex ways with cross-species selection to determine the course of coevolution. Importantly, our model makes empirically testable predictions for how different forms of reciprocal interactions contribute to the coevolutionary process.
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| 11. |
- Enbody, Erik D., et al.
(författare)
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The evolutionary history and mechanistic basis of female ornamentation in a tropical songbird
- 2022
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 76:8, s. 1720-1736
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Tidskriftsartikel (refereegranskat)abstract
- Ornamentation, such as the showy plumage of birds, is widespread among female vertebrates, yet the evolutionary pressures shaping female ornamentation remain uncertain. In part this is due to a poor understanding of the mechanistic route to ornamentation in females. To address this issue, we evaluated the evolutionary history of ornament expression in a tropical passerine bird, the White-shouldered Fairywren, whose females, but not males, strongly vary between populations in occurrence of ornamented black-and-white plumage. We first use phylogenomic analysis to demonstrate that female ornamentation is derived and that female ornamentation evolves independently of changes in male plumage. We then use exogenous testosterone in a field experiment to induce partial ornamentation in naturally unornamented females. By sequencing the transcriptome of experimentally induced ornamented and natural feathers, we identify genes expressed during ornament production and evaluate the degree to which female ornamentation in this system is associated with elevated testosterone, as is common in males. We reveal that some ornamentation in females is linked to testosterone and that sexes differ in ornament-linked gene expression. Lastly, using genomic outlier analysis we identify a candidate melanogenesis gene that lies in a region of high genomic divergence among populations that is also differentially expressed in feather follicles of different female plumages. Taken together, these findings are consistent with sex-specific selection favoring the evolution of female ornaments and demonstrate a key role for testosterone in generating population divergence in female ornamentation through gene regulation. More broadly, our work highlights similarities and differences in how ornamentation evolves in the sexes.
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| 12. |
- Freitas, S., et al.
(författare)
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Parthenogenesis in Darevskia lizards: A rare outcome of common hybridization, not a common outcome of rare hybridization
- 2022
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:5, s. 899-914
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Tidskriftsartikel (refereegranskat)abstract
- Hybridization is a common evolutionary process with multiple possible outcomes. In vertebrates, interspecific hybridization has repeatedly generated parthenogenetic hybrid species. However, it is unknown whether the generation of parthenogenetic hybrids is a rare outcome of frequent hybridization between sexual species within a genus or the typical outcome of rare hybridization events. Darevskia is a genus of rock lizards with both hybrid parthenogenetic and sexual species. Using capture sequencing, we estimate phylogenetic relationships and gene flow among the sexual species, to determine how introgressive hybridization relates to the origins of parthenogenetic hybrids. We find evidence for widespread hybridization with gene flow, both between recently diverged species and deep branches. Surprisingly, we find no signal of gene flow between parental species of the parthenogenetic hybrids, suggesting that the parental pairs were either reproductively or geographically isolated early in their divergence. The generation of parthenogenetic hybrids in Darevskia is, then, a rare outcome of the total occurrence of hybridization within the genus, but the typical outcome when specific species pairs hybridize. Our results question the conventional view that parthenogenetic lineages are generated by hybridization in a window of divergence. Instead, they suggest that some lineages possess specific properties that underpin successful parthenogenetic reproduction.
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| 13. |
- Garamszegi, László Zsolt, et al.
(författare)
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Evolution of relative brain size in dogs—no effects of selection for breed function, litter size, or longevity
- 2023
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Ingår i: Evolution. - 0014-3820 .- 1558-5646. ; 77:7, s. 1591-1606
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Tidskriftsartikel (refereegranskat)abstract
- Domestication is a well-known example of the relaxation of environmentally based cognitive selection that leads to reductions in brain size. However, little is known about how brain size evolves after domestication and whether subsequent directional/artificial selection can compensate for domestication effects. The first animal to be domesticated was the dog, and recent directional breeding generated the extensive phenotypic variation among breeds we observe today. Here we use a novel endocranial dataset based on high-resolution CT scans to estimate brain size in 159 dog breeds and analyze how relative brain size varies across breeds in relation to functional selection, longevity, and litter size. In our analyses, we controlled for potential confounding factors such as common descent, gene flow, body size, and skull shape. We found that dogs have consistently smaller relative brain size than wolves supporting the domestication effect, but breeds that are more distantly related to wolves have relatively larger brains than breeds that are more closely related to wolves. Neither functional category, skull shape, longevity, nor litter size was associated with relative brain size, which implies that selection for performing specific tasks, morphology, and life history does not necessarily influence brain size evolution in domesticated species.
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| 14. |
- Glemin, Sylvain
(författare)
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Balancing selection in self-fertilizing populations
- 2021
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 75:5, s. 1011-1029
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Tidskriftsartikel (refereegranskat)abstract
- Self-fertilization commonly occurs in hermaphroditic species, either occasionally or as the main reproductive mode. It strongly affects the genetic functioning of a population by increasing homozygosity and genetic drift and reducing the effectiveness of recombination. Balancing selection is a form of selection that maintains polymorphism, which has been extensively studied in outcrossing species. Yet, despite recent developments, the analysis of balancing selection in partially selfing species is limited to specific cases and a general treatment is still lacking. In particular, it is unclear whether selfing globally reduced the efficacy of balancing selection as in the well-known case of overdominance. I provide a unifying framework, quantify how selfing affects the maintenance of polymorphism and the efficacy of the different form of balancing selection, and show that they can be classified into two main categories: overdominance-like selection (including true overdominance, selection variable in space and time, and antagonistic selection), which is strongly affected by selfing, and negative frequency dependent selection, which is barely affected by selfing, even at multiple loci. I also provide simple analytical results for all cases under the assumption of weak selection. This framework provides theoretical background to analyze the genomic signature of balancing selection in partially selfing species. It also sheds new light on the evolution of selfing species, including the evolution of selfing syndrome, the interaction with pathogens, and the evolutionary fate of selfing lineages.
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| 15. |
- Harper, Jon Alexander, et al.
(författare)
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Systematic review reveals multiple sexually antagonistic polymorphisms affecting human disease and complex traits
- 2021
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 75:12, s. 3087-3097
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Tidskriftsartikel (refereegranskat)abstract
- An evolutionary model for sex differences in disease risk posits that alleles conferring higher risk in one sex may be protective in the other. These sexually antagonistic (SA) alleles are predicted to be maintained at frequencies higher than expected under purifying selection against unconditionally deleterious alleles, but there are apparently no examples in humans. Discipline-specific terminology, rather than a genuine lack of such alleles, could explain this disparity. We undertook a two-stage review of evidence for SA polymorphisms in humans using search terms from (i) evolutionary biology and (ii) biomedicine. Although the first stage returned no eligible studies, the second revealed 51 genes with sex-opposite effects; 22 increased disease risk or severity in one sex but protected the other. Those with net positive effects occurred at higher frequencies. None were referred to as SA. Our review reveals significant communication barriers to fields as a result of discipline-specific terminology.
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| 16. |
- Holand, Hakon, et al.
(författare)
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Stabilizing selection and adaptive evolution in a combination of two traits in an arctic ungulate
- 2020
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:1, s. 103-115
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Tidskriftsartikel (refereegranskat)abstract
- Stabilizing selection is thought to be common in wild populations and act as one of the main evolutionary mechanisms, which constrain phenotypic variation. When multiple traits interact to create a combined phenotype, correlational selection may be an important process driving adaptive evolution. Here, we report on phenotypic selection and evolutionary changes in two natal traits in a semidomestic population of reindeer (Rangifer tarandus) in northern Finland. The population has been closely monitored since 1969, and detailed data have been collected on individuals since they were born. Over the length of the study period (1969-2015), we found directional and stabilizing selection toward a combination of earlier birth date and heavier birth mass with an intermediate optimum along the major axis of the selection surface. In addition, we demonstrate significant changes in mean traits toward earlier birth date and heavier birth mass, with corresponding genetic changes in breeding values during the study period. Our results demonstrate evolutionary changes in a combination of two traits, which agree closely with estimated patterns of phenotypic selection. Knowledge of the selective surface for combinations of genetically correlated traits are vital to predict how population mean phenotypes and fitness are affected when environments change.
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| 17. |
- Hotzy, Cosima, et al.
(författare)
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Evolutionary history of sexual selection affects microRNA profiles in Drosophila sperm
- 2022
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 76:2, s. 310-319
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Tidskriftsartikel (refereegranskat)abstract
- The presence of small RNAs in sperm is a relatively recent discovery and little is currently known about their importance and functions. Environmental changes including social conditions and dietary manipulations are known to affect the composition and expression of some small RNAs in sperm and may elicit a physiological stress response resulting in an associated change in gamete miRNA profiles. Here, we tested how microRNA profiles in sperm are affected by variation in both sexual selection and dietary regimes in Drosophila melanogaster selection lines. The selection lines were exposed to standard versus low yeast diet treatments and three different population sex ratios (male-biased, female-biased, or equal sex) in a full-factorial design. After 38 generations of selection, all males were maintained on their selected diet and in a common garden male-only environment prior to sperm sampling. We performed transcriptome analyses on miRNAs in purified sperm samples. We found 11 differentially expressed miRNAs with the majority showing differences between male- and female-biased lines. Dietary treatment only had a significant effect on miRNA expression levels in interaction with sex ratio. Our findings suggest that long-term adaptation may affect miRNA profiles in sperm and that these may show varied interactions with short-term environmental changes.
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| 18. |
- Iinatti Brengdahl, Martin, et al.
(författare)
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Age-specific effects of deletions: implications for aging theories
- 2023
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Ingår i: Evolution. - : OXFORD UNIV PRESS. - 0014-3820 .- 1558-5646. ; 77:1, s. 254-263
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of aging requires mutations with late-life deleterious effects. Classic theories assume these mutations either have neutral (mutation accumulation) or beneficial (antagonistic pleiotropy) effects early in life, but it is also possible that they start out as mildly harmful and gradually become more deleterious with age. Despite a wealth of studies on the genetics of aging, we still have a poor understanding of how common mutations with age-specific effects are and what aging theory they support. To advance our knowledge on this topic, we measure a set of genomic deletions for their heterozygous effects on juvenile performance, fecundity at 3 ages, and adult survival. Most deletions have age-specific effects, and these are commonly harmful late in life. Many of the deletions assayed here would thus contribute to aging if present in a population. Taking only age-specific fecundity into account, some deletions support antagonistic pleiotropy, but the majority of them better fit a scenario where their negative effects on fecundity become progressively worse with age. Most deletions have a negative effect on juvenile performance, a fact that strengthens the conclusion that deletions primarily contribute to aging through negative effects that amplify with age.
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| 19. |
- Jiménez-Ortega, Dante, et al.
(författare)
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Long life evolves in large-brained bird lineages
- 2020
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:12, s. 2617-2628
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Tidskriftsartikel (refereegranskat)abstract
- The brain is an energetically costly organ that consumes a disproportionate amount of resources. Species with larger brains relative to their body size have slower life histories, with reduced output per reproductive event and delayed development times that can be offset by increasing behavioral flexibility. The cognitive buffer hypothesis maintains that large brain size decreases extrinsic mortality due to greater behavioral flexibility, leading to a longer lifespan. Alternatively, slow life histories, and long lifespan can be a pre-adaptation for the evolution of larger brains. Here, we use phylogenetic path analysis to contrast different evolutionary scenarios and disentangle direct and indirect relationships between brain size, body size, life history, and longevity across 339 altricial and precocial bird species. Our results support both a direct causal link between brain size and lifespan, and an indirect effect via other life history traits. These results indicate that large brain size engenders longer life, as proposed by the cognitive buffer hypothesis.
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| 20. |
- Joffard, Nina, et al.
(författare)
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Digest : The role of postzygotic isolation in Mimulus speciation
- 2021
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Ingår i: Evolution: international journal of organic evolution. - : Wiley. - 1558-5646 .- 0014-3820. ; 75:3, s. 756-758
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Tidskriftsartikel (refereegranskat)abstract
- Recently diverged species often show incomplete reproductive isolation and subsequently experience hybridization and introgression. The plant genus Mimulus includes many such examples of closely related taxa that prove useful for studying incipient speciation. However, Sandstedt et al. show that in contrast to other Mimulus species, species of the M. tilingii complex are characterized by strong postzygotic isolation mediated by multiple barriers. This finding highlights the diverse speciation histories of related plant groups.
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| 21. |
- Joffard, Nina, et al.
(författare)
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Extensive pollinator sharing does not promote character displacement in two orchid congeners
- 2022
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 76:4, s. 749-764
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Tidskriftsartikel (refereegranskat)abstract
- Pollinator sharing between close relatives can be costly and can promote pollination niche partitioning and floral divergence. This should be reflected by a higher species divergence in sympatry than in allopatry. We tested this hypothesis in two orchid congeners with overlapping distributions and flowering times. We characterized floral traits and pollination niches and quantified pollen limitation in 15 pure and mixed populations, and we measured phenotypic selection on floral traits and performed controlled crosses in one mixed site. Most floral traits differed between species, yet pollinator sharing was extensive. Only the timing of scent emission diverged more in mixed sites than in pure sites, and this was not mirrored by the timing of pollinator visitation. We did not detect divergent selection on floral traits. Seed production was pollen limited in most populations but not more severely in mixed sites than in pure sites. Interspecific crosses produced the same or a higher proportion of viable seeds than intraspecific crosses. The two orchid species attract the same pollinator species despite showing divergent floral traits. However, this does not promote character displacement, implying a low cost of pollinator sharing. Our results highlight the importance of characterizing both traits and ecological niches in character displacement studies.
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| 22. |
- Johansson, Frank, et al.
(författare)
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Natural selection mediated by seasonal time constraints increases the alignment between evolvability and developmental plasticity
- 2021
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 75:2, s. 464-475
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Tidskriftsartikel (refereegranskat)abstract
- Phenotypic plasticity can either hinder or promote adaptation to novel environments. Recent studies that have quantified alignments between plasticity, genetic variation, and divergence propose that such alignments may reflect constraints that bias future evolutionary trajectories. Here, we emphasize that such alignments may themselves be a result of natural selection and do not necessarily indicate constraints on adaptation. We estimated developmental plasticity and broad sense genetic covariance matrices (G) among damselfly populations situated along a latitudinal gradient in Europe. Damselflies were reared at photoperiod treatments that simulated the seasonal time constraints experienced at northern (strong constraints) and southern (relaxed constraints) latitudes. This allowed us to partition the effects of (1) latitude, (2) photoperiod, and (3) environmental novelty on G and its putative alignment with adaptive plasticity and divergence. Environmental novelty and latitude did not affect G, but photoperiod did. Photoperiod increased evolvability in the direction of observed adaptive divergence and developmental plasticity when G was assessed under strong seasonal time constraints at northern (relative to southern) photoperiod. Because selection and adaptation under time constraints is well understood in Lestes damselflies, our results suggest that natural selection can shape the alignment between divergence, plasticity, and evolvability.
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| 23. |
- Koch, E. L., et al.
(författare)
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Genetic architecture of repeated phenotypic divergence in Littorina saxatilis ecotype evolution
- 2022
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:10, s. 2332-2346
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Tidskriftsartikel (refereegranskat)abstract
- Chromosomal inversions have been shown to play a major role in a local adaptation by suppressing recombination between alternative arrangements and maintaining beneficial allele combinations. However, so far, their importance relative to the remaining genome remains largely unknown. Understanding the genetic architecture of adaptation requires better estimates of how loci of different effect sizes contribute to phenotypic variation. Here, we used three Swedish islands where the marine snail Littorina saxatilis has repeatedly evolved into two distinct ecotypes along a habitat transition. We estimated the contribution of inversion polymorphisms to phenotypic divergence while controlling for polygenic effects in the remaining genome using a quantitative genetics framework. We confirmed the importance of inversions but showed that contributions of loci outside inversions are of similar magnitude, with variable proportions dependent on the trait and the population. Some inversions showed consistent effects across all sites, whereas others exhibited site-specific effects, indicating that the genomic basis for replicated phenotypic divergence is only partly shared. The contributions of sexual dimorphism as well as environmental factors to phenotypic variation were significant but minor compared to inversions and polygenic background. Overall, this integrated approach provides insight into the multiple mechanisms contributing to parallel phenotypic divergence. © 2022 The Authors. Evolution published by Wiley Periodicals LLC on behalf of The Society for the Study of Evolution.
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| 24. |
- Lund-Hansen, Katrine K., et al.
(författare)
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Feminization of complex traits in Drosophila melanogaster via female-limited X chromosome evolution
- 2020
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:12, s. 2703-2713
-
Tidskriftsartikel (refereegranskat)abstract
- A handful of studies have investigated sexually antagonistic constraints on achieving sex-specific fitness optima, although exclusively through male-genome-limited evolution experiments. In this article, we established a female-limited X chromosome evolution experiment, where we used an X chromosome balancer to enforce the inheritance of the X through the matriline, thus removing exposure to male selective constraints. This approach eliminates the effects of sexually antagonistic selection on the X chromosome, permitting evolution toward a single sex-specific optimum. After multiple generations of selection, we found strong evidence that body size and development time had moved toward a female-specific optimum, whereas reproductive fitness and locomotion activity remained unchanged. The changes in body size and development time are consistent with previous results, and suggest that the X chromosome is enriched for sexually antagonistic genetic variation controlling these particular traits. The lack of change in reproductive fitness and locomotion activity could be due to a number of mutually nonexclusive explanations, including a lack of sexually antagonistic variance on the X chromosome for those traits or confounding effects of the use of the balancer chromosome. This study is the first to employ female-genome-limited selection and adds to the understanding of the complexity of sexually antagonistic genetic variation.
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| 25. |
- Macartney, Erin, et al.
(författare)
-
Intra-specific correlations between ejaculate traits and competitive fertilization success : a meta-analysis across species and fertilization modes
- 2023
-
Ingår i: Evolution. - 0014-3820 .- 1558-5646. ; 78:3, s. 497-510
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding of how selection can act on traits that improve competitiveness and subsequent paternity has advanced, including the idea that internal and external fertilization presents different environments that may select differentially on ejaculate traits. However, no studies have quantitatively synthesized the intra-specific relationships between these traits and paternity. Therefore, we conducted a meta-analysis across 52 papers to determine which ejaculate traits positively correlate with paternity share and how these correlations vary with fertilization mode. Overall, most ejaculate traits were positively associated with paternity, with the notable exception of sperm length. Sub-analyses on sperm number, sperm length, and sperm velocity revealed no statistical differences between fertilization modes in the relationship between traits and paternity when all effect sizes across species were combined. However, in a sub-analysis on fish species only, we found evidence that sperm velocity may be more important in external fertilizers. We also observed differences in the importance of phylogenetic relatedness and some species-specific differences. Our results suggest that while most ejaculate traits should be under positive directional selection in both internal and external fertilizers, sperm length may be subject to more nuanced selection pressures. Overall, we highlight important patterns of intra-specific relationships between ejaculate traits and competitive fertilization success.
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| 26. |
- Martí, Emiliano, et al.
(författare)
-
Cytogenomic analysis unveils mixed molecular evolution and recurrent chromosomal rearrangements shaping the multigene families on Schistocerca grasshopper genomes
- 2021
-
Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 75:8, s. 2027-2041
-
Tidskriftsartikel (refereegranskat)abstract
- Multigene families are essential components of eukaryotic genomes and play key roles either structurally and functionally. Their modes of evolution remain elusive even in the era of genomics, because multiple multigene family sequences coexist in genomes, particularly in large repetitive genomes. Here, we investigate how the multigene families 18S rDNA, U2 snDNA, and H3 histone evolved in 10 species of Schistocerca grasshoppers with very large and repeat-enriched genomes. Using sequenced genomes and fluorescence in situ hybridization mapping, we find substantial differences between species, including the number of chromosomal clusters, changes in sequence abundance and nucleotide composition, pseudogenization, and association with transposable elements (TEs). The intragenomic analysis of Schistocerca gregaria using long-read sequencing and genome assembly unveils conservation for H3 histone and recurrent pseudogenization for 18S rDNA and U2 snDNA, likely promoted by association with TEs and sequence truncation. Remarkably, TEs were frequently associated with truncated copies, were also among the most abundant in the genome, and revealed signatures of recent activity. Our findings suggest a combined effect of concerted and birth-and-death models driving the evolution of multigene families in Schistocerca over the last 8 million years, and the occurrence of intra- and interchromosomal rearrangements shaping their chromosomal distribution. Despite the conserved karyotype in Schistocerca, our analysis highlights the extensive reorganization of repetitive DNAs in Schistocerca, contributing to the advance of comparative genomics for this important grasshopper genus.
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| 27. |
- Martinossi-Allibert, Ivain, 1991-, et al.
(författare)
-
Female-specific resource limitation does not make the opportunity for selection more female biased
- 2020
-
Ingår i: Evolution. - : WILEY. - 0014-3820 .- 1558-5646. ; 74:12, s. 2714-2724
-
Tidskriftsartikel (refereegranskat)abstract
- Competition for limiting resources and stress can magnify variance in fitness and therefore selection. But even in a common environment, the strength of selection can differ across the sexes, as their fitness is often limited by different factors. Indeed, most taxa show stronger selection in males, a bias often ascribed to intense competition for access to mating partners. This sex bias could reverberate on many aspects of evolution, from speed of adaptation to genome evolution. It is unclear, however, whether stronger opportunity for selection in males is a pattern robust to sex-specific stress or resource limitation. We test this in the model speciesCallosobruchus maculatusby comparing female and male opportunity for selection (i) with and without limitation of quality oviposition sites, and (ii) under delayed age at oviposition. Decreasing the abundance of the resource key to females or increasing their reproductive age was challenging, as shown by a reduction in mean fitness, but opportunity for selection remained stronger in males across all treatments, and even more so when oviposition sites were limiting. This suggests that males remain the more variable sex independent of context, and that the opportunity for selection through males is indirectly affected by female-specific resource limitation.
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| 28. |
- Martinossi-Allibert, Ivain, 1991-, et al.
(författare)
-
Invasion and maintenance of meiotic drivers in populations of ascomycete fungi
- 2021
-
Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 75:5, s. 1150-1169
-
Tidskriftsartikel (refereegranskat)abstract
- Meiotic drivers (MDs) are selfish genetic elements that are able to become overrepresented among the products of meiosis. This transmission advantage makes it possible for them to spread in a population even when they impose fitness costs on their host organisms. Whether an MD can invade a population, and subsequently reach fixation or coexist in a stable polymorphism, depends on the one hand on the biology of the host organism, including its life cycle, mating system, and population structure, and on the other hand on the specific fitness effects of the driving allele on the host. Here, we present a population genetic model for spore killing, a type of drive specific to fungi. We show how ploidy level, rate of selfing, and efficiency of spore killing affect the invasion probability of a driving allele and the conditions for its stable coexistence with a nondriving allele. Our model can be adapted to different fungal life cycles, and is applied here to two well-studied genera of filamentous ascomycetes known to harbor spore-killing elements, Neurospora and Podospora. We discuss our results in the light of recent empirical findings for these two systems.
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| 29. |
- Naresh, Vinesh Shenoi, et al.
(författare)
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On aging and age-specific effects of spontaneous mutations
- 2023
-
Ingår i: Evolution. - : Oxford University Press. - 0014-3820 .- 1558-5646. ; 77:8, s. 1780-1790
-
Tidskriftsartikel (refereegranskat)abstract
- Evolutionary theory assumes that mutations that cause aging either have beneficial early-life effects that gradually become deleterious with advancing age (antagonistic pleiotropy [AP]) or that they only have deleterious effects at old age (mutation accumulation [MA]). Mechanistically, aging is predicted to result from damage accumulating in the soma. While this scenario is compatible with AP, it is not immediately obvious how damage would accumulate under MA. In a modified version of the MA theory, it has been suggested that mutations with weakly deleterious effects at young age can also contribute to aging, if they generate damage that gradually accumulates with age. Mutations with increasing deleterious effects have recently gained support from theoretical work and studies of large-effect mutations. Here we address if spontaneous mutations also have negative effects that increase with age. We accumulate mutations with early-life effects in Drosophila melanogaster across 27 generations and compare their relative effects on fecundity early and late in life. Our mutation accumulation lines on average have substantially lower early-life fecundity compared to controls. These effects were further maintained throughout life, but they did not increase with age. Our results suggest that most spontaneous mutations do not contribute to damage accumulation and aging.
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| 30. |
- Nielsen, Matthew E., et al.
(författare)
-
Why study plasticity in multiple traits? New hypotheses for how phenotypically plastic traits interact during development and selection
- 2022
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:5, s. 858-869
-
Tidskriftsartikel (refereegranskat)abstract
- Organisms can often respond adaptively to a change in their environment through phenotypic plasticity in multiple traits, a phenomenon termed as multivariate plasticity. These different plastic responses could interact and affect each other's development as well as selection on each other, but the causes and consequences of these interactions have received relatively little attention. Here, we propose a new conceptual framework for understanding how different plastic responses can affect each other's development and why organisms should have multiple plastic responses. A plastic change in one trait could alter the phenotype of a second plastic trait by changing either the cue received by the organism (cue-mediated effect) or the response to that cue (response-mediated effect). Multivariate plasticity could benefit the organism either because the plastic responses work better when expressed together (synergy) or because each response is more effective under different environmental circumstances (complementarity). We illustrate these hypotheses with case studies, focusing on interactions between behavior and morphology, plastic traits that differ in their reversibility. Future empirical and theoretical research should investigate the consequences of these interactions for additional factors important for the evolution of plasticity, such as the limits and costs of plasticity.
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| 31. |
- Nordén, Anna K., et al.
(författare)
-
Rapid evolution of sex role specialization in a hermaphrodite under sex-limited selection
- 2023
-
Ingår i: Evolution; international journal of organic evolution. - : Oxford University Press (OUP). - 1558-5646. ; 77:4, s. 1066-1076
-
Tidskriftsartikel (refereegranskat)abstract
- The evolution of separate sexes from hermaphroditism is thought to have occurred independently many times, and may be linked to the evolution of sex chromosomes. Even though we have a good understanding of the theoretical steps in the evolution of sex chromosomes from a hermaphrodite ancestor, the initial stages are still hard to study in animals because many well-studied animal sex chromosome systems are old. We addressed this problem by experimentally selecting a hermaphrodite via sex-limited experimental evolution for several generations, simulating the early stages in the evolution of a sex chromosome. After 14 generations, a fitness assay revealed evidence of incipient sex role specialization in the female-selected lines, presumably reflecting the release from constraints usually imposed by selection on the other sex role. Importantly, however, this was not simply explained by morphology because testis and ovary sizes did not diverge among treatments. There was no evidence of a change in the male-selected lines. Our study shows that sex role specialization can occur rapidly as a result of sex-limited selection, which is consistent with genetic constraints between sex roles, and in line with the first predicted steps toward the evolution of a new sex chromosome system.
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| 32. |
- O'Connor, Emily, et al.
(författare)
-
Tradeoffs in expressed major histocompatibility complex diversity seen on a macro‐evolutionary scale among songbirds
- 2021
-
Ingår i: Evolution: international journal of organic evolution. - : Wiley. - 1558-5646.
-
Tidskriftsartikel (refereegranskat)abstract
- To survive organisms must defend themselves against pathogens. Classical Major Histocompatibility Complex (MHC) genes play a key role in pathogen defense by encoding molecules involved in pathogen recognition. MHC gene diversity influences the variety of pathogens individuals can recognize and respond to and has consequently been a popular genetic marker for disease resistance in ecology and evolution. However, MHC diversity is predominantly estimated using genomic DNA (gDNA) with little knowledge of expressed diversity. This limits our ability to interpret the adaptive significance of variation in MHC diversity, especially in species with very many MHC genes such as songbirds. Here, we address this issue using phylogenetic comparative analyses of the number of MHC class I alleles (MHC‐I diversity) in gDNA and complementary DNA (cDNA), that is, expressed alleles, across 13 songbird species. We propose three theoretical relationships that could be expected between genomic and expressed MHC‐I diversity on a macroevolutionary scale and test which of these are best supported. In doing so, we show that significantly fewer MHC‐I alleles than the number available are expressed, suggesting that optimal MHC‐I diversity could be achieved by modulating gene expression. Understanding the relationship between genomic and expressed MHC diversity is essential for interpreting variation in MHC diversity in an evolutionary context.
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| 33. |
- Olito, Colin, et al.
(författare)
-
Consequences of partially recessive deleterious genetic variation for the evolution of inversions suppressing recombination between sex chromosomes
- 2022
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:6, s. 1320-1330
-
Tidskriftsartikel (refereegranskat)abstract
- The evolution of suppressed recombination between sex chromosomes is widely hypothesized to be driven by sexually antagonistic selection (SA), where tighter linkage between the sex-determining gene(s) and nearby SA loci is favored when it couples male-beneficial alleles to the proto-Y chromosome, and female-beneficial alleles to the proto-X. Despite limited empirical evidence, the SA selection hypothesis overshadows several alternatives, including an incomplete but often-repeated “sheltering hypothesis” that suggests that expansion of the sex-linked region (SLR) reduces homozygous expression of partially recessive deleterious mutations at selected loci. Here, we use population genetic models to evaluate the consequences of deleterious mutational variation for the evolution of neutral chromosomal inversions expanding the SLR on proto-Y chromosomes. We find that SLR-expanding inversions face a race against time: lightly loaded inversions are initially beneficial, but eventually become deleterious as they accumulate new mutations, and must fix before this window of opportunity closes. The outcome of this race is strongly influenced by inversion size, the mutation rate, and the dominance coefficient of deleterious mutations. Yet, small inversions have elevated fixation probabilities relative to neutral expectations for biologically plausible parameter values. Our results demonstrate that deleterious genetic variation can plausibly drive recombination suppression in small steps and would be most consistent with empirical patterns of small evolutionary strata or gradual recombination arrest.
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| 34. |
- Olito, Colin, et al.
(författare)
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The evolution of suppressed recombination between sex chromosomes and the lengths of evolutionary strata
- 2023
-
Ingår i: Evolution; international journal of organic evolution. - : Oxford University Press (OUP). - 1558-5646. ; 77:4, s. 1077-1090
-
Tidskriftsartikel (refereegranskat)abstract
- The idea that sex differences in selection drive the evolution of suppressed recombination between sex chromosomes is well developed in population genetics. Yet, despite a now classic body of theory, empirical evidence that sexually antagonistic selection drives the evolution of recombination arrest remains equivocal and alternative hypotheses underdeveloped. Here, we investigate whether the length of "evolutionary strata" formed by chromosomal inversions (or other large-effect recombination modifiers) expanding the non-recombining sex-linked region (SLR) on sex chromosomes can be informative of how selection influenced their fixation. We develop population genetic models to show how the length of an SLR-expanding inversion, and the presence of partially recessive deleterious mutational variation, affect the fixation probability of three different classes of inversions: (1) intrinsically neutral, (2) directly beneficial (i.e., due to breakpoint or positional effects), and (3) those capturing sexually antagonistic (SA) loci. Our models indicate that neutral inversions, and those capturing an SA locus in linkage disequilibrium with the ancestral SLR, will exhibit a strong fixation bias toward small inversions; while unconditionally beneficial inversions, and those capturing a genetically unlinked SA locus, will favor fixation of larger inversions. The footprint of evolutionary stratum size left behind by different selection regimes is strongly influenced by parameters affecting the deleterious mutation load, the physical position of the ancestral SLR, and the distribution of new inversion lengths.
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| 35. |
- Ottenburghs, Jente
(författare)
-
Digest : Exploring genomic islands of differentiation on the Z chromosome of hummingbirds
- 2020
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:4, s. 793-794
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- What evolutionary processes shaped the genomic landscape of differentiation in Selasphorus hummingbirds? Battey shows that the islands of differentiation on the Z chromosome are most likely the outcome of linked selection. Furthermore, these islands might contain barrier loci that contribute to reproductive isolation between these hybridizing hummingbirds.
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| 36. |
- Ottenburghs, Jente
(författare)
-
Digest : Avian genomes are permeable to introgression for a few million years
- 2020
-
Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 74:5, s. 1010-1011
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Tidskriftsartikel (refereegranskat)abstract
- How wide is the time window for introgression after divergence? Pulido-Santacruz et al. addressed this question by studying the evolutionary history of the bird genus Dendrocincla. They found five introgression events that occurred between a few hundred thousand and around 2.5 million years after divergence. The introgressed genomic proportion declined exponentially with the age of the hybridizing taxa. Hence, this study suggests that species boundaries are permeable up to 2.5 million years after divergence.
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| 37. |
- Pap, Péter L., et al.
(författare)
-
Down feather morphology reflects adaptation to habitat and thermal conditions across the avian phylogeny
- 2020
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:10, s. 2365-2376
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Tidskriftsartikel (refereegranskat)abstract
- Down feathers are the first feather types that appear in both the phylogenetic and the ontogenetic history of birds. Although it is widely acknowledged that the primary function of downy elements is insulation, little is known about the interspecific variability in the structural morphology of these feathers, and the environmental factors that have influenced their evolution. Here, we collected samples of down and afterfeathers from 156 bird species and measured key morphological characters that define the insulatory properties of the downy layer. We then tested if habitat and climatic conditions could explain the observed between-species variation in down feather structure. We show that habitat has a very strong and clearly defined effect on down feather morphology. Feather size, barbule length and nodus density all decreased from terrestrial toward aquatic birds, with riparian species exhibiting intermediate characters. Wintering climate, expressed as windchill (a combined measure of the ambient temperature and wind speed) had limited effects on down morphology, colder climate only being associated with higher nodus density in dorsal down feathers. Overall, an aquatic lifestyle selects for a denser plumulaceous layer, while the effect of harsh wintering conditions on downy structures appear limited. These results provide key evidence of adaptations to habitat at the level of the downy layer, both on the scale of macro- and micro-elements of the plumage. Moreover, they reveal characters of convergent evolution in the avian plumage and mammalian fur, that match the varying needs of insulation in terrestrial and aquatic modes of life.
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| 38. |
- Parrett, Jonathan M., et al.
(författare)
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A sexually selected male weapon characterized by strong additive genetic variance and no evidence for sexually antagonistic polyphenic maintenance
- 2023
-
Ingår i: Evolution. - : Oxford University Press (OUP). - 0014-3820 .- 1558-5646. ; 77:6, s. 1289-1302
-
Tidskriftsartikel (refereegranskat)abstract
- Sexual selection and sexual antagonism are important drivers of eco-evolutionary processes. The evolution of traits shaped by these processes depends on their genetic architecture, which remains poorly studied. Here, implementing a quantitative genetics approach using diallel crosses of the bulb mite, Rhizoglyphus robini, we investigated the genetic variance that underlies a sexually selected weapon that is dimorphic among males and female fecundity. Previous studies indicated that a negative genetic correlation between these two traits likely exists. We found male morph showed considerable additive genetic variance, which is unlikely to be explained solely by mutation-selection balance, indicating the likely presence of large-effect loci. However, a significant magnitude of inbreeding depression also indicates that morph expression is likely to be condition-dependent to some degree and that deleterious recessives can simultaneously contribute to morph expression. Female fecundity also showed a high degree of inbreeding depression, but the variance in female fecundity was mostly explained by epistatic effects, with very little contribution from additive effects. We found no significant genetic correlation, nor any evidence for dominance reversal, between male morph and female fecundity. The complex genetic architecture underlying male morph and female fecundity in this system has important implications for our understanding of the evolutionary interplay between purifying selection and sexually antagonistic selection.
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| 39. |
- Peede, David, et al.
(författare)
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Digest : Species delimitation in the face of demographic processes
- 2020
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:2, s. 499-500
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Existing approaches to species delimitation use the extent of divergence between taxa. However, processes, such as gene flow during divergence or secondary contact, as well as population expansion and migration, complicate this task. Smith and Carstens introduce the R package delimitR, which uses machine learning to integrate gene flow into species delimitation inference.
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| 40. |
- Perini, Samuel, 1990, et al.
(författare)
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Assortative mating, sexual selection, and their consequences for gene flow in Littorina
- 2020
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:7, s. 1482-1497
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Tidskriftsartikel (refereegranskat)abstract
- When divergent populations are connected by gene flow, the establishment of complete reproductive isolation usually requires the joint action of multiple barrier effects. One example where multiple barrier effects are coupled consists of a single trait that is under divergent natural selection and also mediates assortative mating. Such multiple-effect traits can strongly reduce gene flow. However, there are few cases where patterns of assortative mating have been described quantitatively and their impact on gene flow has been determined. Two ecotypes of the coastal marine snail,Littorina saxatilis, occur in North Atlantic rocky-shore habitats dominated by either crab predation or wave action. There is evidence for divergent natural selection acting on size, and size-assortative mating has previously been documented. Here, we analyze the mating pattern inL. saxatiliswith respect to size in intensively sampled transects across boundaries between the habitats. We show that the mating pattern is mostly conserved between ecotypes and that it generates both assortment and directional sexual selection for small male size. Using simulations, we show that the mating pattern can contribute to reproductive isolation between ecotypes but the barrier to gene flow is likely strengthened more by sexual selection than by assortment.
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| 41. |
- Petrén, Hampus, et al.
(författare)
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Differences in mating system and predicted parental conflict affect post-pollination reproductive isolation in a flowering plant
- 2023
-
Ingår i: Evolution; international journal of organic evolution. - : Oxford University Press (OUP). - 1558-5646 .- 0014-3820. ; 77:4, s. 1019-1030
-
Tidskriftsartikel (refereegranskat)abstract
- Mating system shifts from outcrossing to selfing are frequent in plant evolution. Relative to outcrossing, selfing is associated with reduced parental conflict over seed provisioning, which may result in postzygotic, asymmetric, reproductive isolation in crosses between populations of different mating systems. To test the hypothesis that post-pollination reproductive isolation between populations increases with increasing differences in mating system and predicted parental conflict, we performed a crossing experiment involving all combinations of three self-compatible populations (with low outcrossing rates), and three self-incompatible populations (with high outcrossing rates) of the arctic-alpine herb Arabis alpina, assessing fitness-related seed and plant traits of the progeny. Predicted levels of parental conflict ("genome strength") were quantified based on strength of self-incompatibility and estimates of outcrossing rates. Crosses between self-compatible and self-incompatible populations yielded very small seeds of low viability, resulting in strong reproductive isolation. In 14 of 15 reciprocal between-population crosses, seeds were heavier when the paternal plant had the stronger genome, and seed mass differences between cross directions increased with an increased difference in parental conflict. Overall, our results suggest that, when sufficiently large, differences in mating system and hence in expected parental conflict may result in strong post-pollination reproductive barriers contributing to speciation.
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| 42. |
- Rafajlović, Marina, 1983, et al.
(författare)
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Inversions and genomic differentiation after secondary contact: When drift contributes to maintenance, not loss, of differentiation
- 2021
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 75:6, s. 1288-1303
-
Tidskriftsartikel (refereegranskat)abstract
- Due to their effects on reducing recombination, chromosomal inversions may play an important role in speciation by establishing and/or maintaining linked blocks of genes causing reproductive isolation (RI) between populations. This view fits empirical data indicating that inversions typically harbor loci involved in RI. However, previous computer simulations of infinite populations with two to four loci involved in RI implied that, even with gene flux as low as 10(-8) per gamete, per generation between alternative arrangements, inversions may not have large, qualitative advantages over collinear regions in maintaining population differentiation after secondary contact. Here, we report that finite population sizes can help counteract the homogenizing consequences of gene flux, especially when several fitness-related loci reside within the inversion. In these cases, the persistence time of differentiation after secondary contact can be similar to when gene flux is absent and notably longer than the persistence time without inversions. Thus, despite gene flux, population differentiation may be maintained for up to 100,000 generations, during which time new incompatibilities and/or local adaptations might accumulate and facilitate progress toward speciation. How often these conditions are met in nature remains to be determined.
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| 43. |
- Raj Pant, Sara, et al.
(författare)
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The contribution of extra-pair paternity to the variation in lifetime and age-specific male reproductive success in a socially monogamous species
- 2022
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:5, s. 915-930
-
Tidskriftsartikel (refereegranskat)abstract
- In socially monogamous species, extra-pair paternity (EPP) is predicted to increase variance in male reproductive success (RS) beyond that resulting from genetic monogamy, thus, increasing the “opportunity for selection” (maximum strength of selection that can act on traits). This prediction is challenging to investigate in wild populations because lifetime reproduction data are often incomplete. Moreover, age-specific variances in reproduction have been rarely quantified. We analyzed 21 years of near-complete social and genetic reproduction data from an insular population of Seychelles warblers (Acrocephalus sechellensis). We quantified EPP's contribution to lifetime and age-specific opportunities for selection in males. We compared the variance in male genetic RS vs social (“apparent”) RS (RSap) to assess if EPP increased the opportunity for selection over that resulting from genetic monogamy. Despite not causing a statistically significant excess (19%) of the former over the latter, EPP contributed substantially (27%) to the variance in lifetime RS, similarly to within-pair paternity (WPP, 39%) and to the positive WPP-EPP covariance (34%). Partitioning the opportunity for selection into age-specific (co)variance components, showed that EPP also provided a substantial contribution at most ages, varying with age. Therefore, despite possibly not playing the main role in shaping sexual selection in Seychelles warblers, EPP provided a substantial contribution to the lifetime and age-specific opportunity for selection, which can influence evolutionary processes in age-structured populations.
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| 44. |
- Robert, Alois, et al.
(författare)
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Digest : Population genomics reveals convergence toward melanism in different island populations
- 2021
-
Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 75:6, s. 1582-1584
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Distinct traits between mainland and island populations provide an excellent opportunity to study the evolution and genetic basis of these traits. In this issue, Walsh et al. unraveled the evolution of black plumage color that arose independently in two island populations of the white-winged fairywren. They also described the first steps in understanding the genetic underpinnings of this trait.
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| 45. |
- Roth, Steffen, et al.
(författare)
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The evolution of female-biased genital diversity in bedbugs (Cimicidae)
- 2024
-
Ingår i: Evolution. - : Oxford University Press. - 0014-3820 .- 1558-5646. ; 78:2, s. 329-341
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Tidskriftsartikel (refereegranskat)abstract
- Rapid genitalia evolution is believed to be mainly driven by sexual selection. Recently, noncopulatory genital functions have been suggested to exert stronger selection pressure on female genitalia than copulatory functions. In bedbugs (Cimicidae), the impact of the copulatory function can be isolated from the noncopulatory impact. Unlike in other taxa, female copulatory organs have no function in egg-laying or waste-product expulsion. Males perform traumatic mating by piercing the female integument, thereby imposing antagonistic selection on females and suspending selection to morphologically match female genitalia. We found the location of the copulatory organ evolved rapidly, changing twice between dorsal and ventral sides, and several times along the anteroposterior and the left-right axes. Male genital length and shape varied much less, did not appear to follow the positional changes seen in females, and showed no evidence for coevolution. Female genitalia position evolved 1.5 times faster than male genital length and shape and showed little neutral or geographic signals. Instead, we propose that nonmorphological male traits, such as mating behavior, may drive female genitalia morphology in this taxon. Models of genitalia evolution may benefit from considering morphological genital responses to nonmorphological stimuli, such as male mating behavior or copulatory position.
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| 46. |
- Råberg, Lars, et al.
(författare)
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MHC class II genotype-by-pathogen genotype interaction for infection prevalence in a natural rodent-Borrelia system
- 2022
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:9, s. 2067-2075
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Tidskriftsartikel (refereegranskat)abstract
- MHC genes are extraordinarily polymorphic in most taxa. Host-pathogen coevolution driven by negative frequency-dependent selection (NFDS) is one of the main hypotheses for the maintenance of such immunogenetic variation. Here, we test a critical but rarely tested assumption of this hypothesis—that MHC alleles affect resistance/susceptibility to a pathogen in a strain-specific way, that is, there is a host genotype-by-pathogen genotype interaction. In a field study of bank voles naturally infected with the tick-transmitted bacterium Borrelia afzelii, we tested for MHC class II (DQB) genotype-by-B. afzelii strain interactions for infection prevalence between 10 DQB alleles and seven strains. One allele (DQB*37) showed an interaction, such that voles carrying DQB*37 had higher prevalence of two strains and lower prevalence of one strain than individuals without the allele. These findings were corroborated by analyses of strain composition of infections, which revealed an effect of DQB*37 in the form of lower β diversity among infections in voles carrying the allele. Taken together, these results provide rare support at the molecular genetic level for a key assumption of models of antagonistic coevolution through NFDS.
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| 47. |
- Salces-Castellano, A., et al.
(författare)
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Long-term cloud forest response to climate warming revealed by insect speciation history
- 2021
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 75:2, s. 231-244
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Tidskriftsartikel (refereegranskat)abstract
- Montane cloud forests are areas of high endemism, and are one of the more vulnerable terrestrial ecosystems to climate change. Thus, understanding how they both contribute to the generation of biodiversity, and will respond to ongoing climate change, are important and related challenges. The widely accepted model for montane cloud forest dynamics involves upslope forcing of their range limits with global climate warming. However, limited climate data provides some support for an alternative model, where range limits are forced downslope with climate warming. Testing between these two models is challenging, due to the inherent limitations of climate and pollen records. We overcome this with an alternative source of historical information, testing between competing model predictions using genomic data and demographic analyses for a species of beetle tightly associated to an oceanic island cloud forest. Results unequivocally support the alternative model: populations that were isolated at higher elevation peaks during the Last Glacial Maximum are now in contact and hybridizing at lower elevations. Our results suggest that genomic data are a rich source of information to further understand how montane cloud forest biodiversity originates, and how it is likely to be impacted by ongoing climate change.
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| 48. |
- Schrader, Matthew, et al.
(författare)
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Larval environmental conditions influence plasticity in resource use by adults in the burying beetle, Nicrophorus vespilloides
- 2022
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:3, s. 667-674
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have shown that intraspecific patterns of phenotypic plasticity can mirror patterns of evolutionary diversification among species. This appears to be the case in Nicrophorus beetles. Within species, body size is positively correlated with the size of carrion used to provision larvae and parental performance. Likewise, among species, variation in body size influences whether species exploit smaller or larger carrion and the extent to which larvae depend on parental care. However, it is unclear whether developmental plasticity in response to carcass size, parental care, or both underlie transitions to new carcass niches. We examined this by testing whether variation in the conditions experienced by Nicrophorus vespilloides larvae influenced their ability to breed efficiently upon differently sized carcasses as adults. We found that the conditions experienced by larvae during development played a critical role in determining their ability to use large carcasses effectively as adults. Specifically, individuals that developed with parental care and on large carcasses were best able to convert the resources on a large carcass into offspring when breeding themselves. Our results suggest that parentally induced plasticity can be important in the initial stages of niche expansion.
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| 49. |
- Sha, Yongcui, et al.
(författare)
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Ancestral environment determines the current reaction to ultraviolet radiation in Daphnia magna
- 2022
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:8, s. 1821-1835
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Tidskriftsartikel (refereegranskat)abstract
- An individual's phenotype can be altered by direct contact with its present environment but also by environmental features experienced by previous generations, that is, parental or grandparental effects. However, the strength and direction of these transgenerational effects may be highly variable according to the ecological conditions experienced by ancestral generations. Here, we performed a reciprocal split-brood experiment to compare transgenerational responses to the threat of ultraviolet radiation (UVR) in the zooplankter Daphnia magna, which had, or had not, been exposed to UVR for more than 150 generations. We found that the environment at which parents and grandparents were reared significantly influenced both behavior and life-history traits of their descendants. However, such transgenerational responses differed between D. magna individuals with contrasting ancestral stress history, that is, when exposed to UVR previously unexposed individuals rapidly changed their behavior and life-history traits, whereas individuals previously exposed to UVR showed less pronounced response when the UVR threat level relaxed. Hence, we here demonstrate an asymmetric transgenerational plasticity in response to UVR threat. The findings advance our understanding on the evolutionary ecology of such transgenerational effects and their potential role in response to changes in the local environment.
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| 50. |
- Silva, Willian T.A.F.
(författare)
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Digest : A synergistic approach explains the evolutionary connection between brain size and longevity*
- 2020
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 74:12, s. 2743-2745
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Tidskriftsartikel (refereegranskat)abstract
- The cognitive buffer hypothesis poses that brain size evolves to buffer individuals from environmental changes, increasing survival. Jiménez-Ortega et al. (2020) explored this hypothesis using a phylogenetic path analysis and showed that there is a direct causal link between brain size and longevity in birds, even when allometric effects are taken into account. Furthermore, a synergistic model was better supported than models that included independent effects of brain size and body size.
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