| 1. |
- Aalberg Haugen, Inger M., 1980-, et al.
(författare)
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The evolution of alternative developmental pathways : footprints of selection on life-history traits in a butterfly
- 2012
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 25:7, s. 1377-1388
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Tidskriftsartikel (refereegranskat)abstract
- Developmental pathways may evolve to optimize alternative phenotypes across environments. However, the maintenance of such adaptive plasticity under relaxed selection has received little study. We compare the expression of life-history traits across two developmental pathways in two populations of the butterfly Pararge aegeria where both populations express a diapause pathway but one never expresses direct development in nature. In the population with ongoing selection on both pathways, the difference between pathways in development time and growth rate was larger, whereas the difference in body size was smaller compared with the population experiencing relaxed selection on one pathway. This indicates that relaxed selection on the direct pathway has allowed life-history traits to drift towards values associated with lower fitness when following this pathway. Relaxed selection on direct development was also associated with a higher degree of genetic variation for protandry expressed as within-family sexual dimorphism in growth rate. Genetic correlations for larval growth rate across sexes and pathways were generally positive, with the notable exception of correlation estimates that involved directly developing males of the population that experienced relaxed selection on this pathway. We conclude that relaxed selection on one developmental pathway appears to have partly disrupted the developmental regulation of life-history trait expression. This in turn suggests that ongoing selection may be responsible for maintaining adaptive developmental regulation along alternative developmental pathways in these populations.
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| 2. |
- Abbott, Jessica K., 1978-, et al.
(författare)
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Sexual conflict in wing size and shape in Drosophila melanogaster
- 2010
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 23:9, s. 1989-1997
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Tidskriftsartikel (refereegranskat)abstract
- Intralocus sexual conflict occurs when opposing selection pressures operate on loci expressed in both sexes, constraining the evolution of sexual dimorphism and displacing one or both sexes from their optimum. We eliminated intralocus conflict in Drosophila melanogaster by limiting transmission of all major chromosomes to males, thereby allowing them to win the intersexual tug-of-war. Here, we show that this male-limited (ML) evolution treatment led to the evolution (in both sexes) of masculinized wing morphology, body size, growth rate, wing loading, and allometry. In addition to more male-like size and shape, ML evolution resulted in an increase in developmental stability for males. However, females expressing ML chromosomes were less developmentally stable, suggesting that being ontogenetically more male-like was disruptive to development. We suggest that sexual selection over size and shape of the imago may therefore explain the persistence of substantial genetic variation in these characters and the ontogenetic processes underlying them.
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| 3. |
- Abbott, Jessica K., et al.
(författare)
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The microevolutionary response to male-limited X-chromosome evolution in Drosophila melanogaster reflects macroevolutionary patterns
- 2020
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Ingår i: Journal of Evolutionary Biology. - : Wiley-Blackwell. - 1010-061X .- 1420-9101. ; 33:6, s. 738-750
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Tidskriftsartikel (refereegranskat)abstract
- Due to its hemizygous inheritance and role in sex determination, the X-chromosome is expected to play an important role in the evolution of sexual dimorphism and to be enriched for sexually antagonistic genetic variation. By forcing the X-chromosome to only be expressed in males over >40 generations, we changed the selection pressures on the X to become similar to those experienced by the Y. This releases the X from any constraints arising from selection in females and should lead to specialization for male fitness, which could occur either via direct effects of X-linked loci or trans-regulation of autosomal loci by the X. We found evidence of masculinization via up-regulation of male-benefit sexually antagonistic genes and down-regulation of X-linked female-benefit genes. Potential artefacts of the experimental evolution protocol are discussed and cannot be wholly discounted, leading to several caveats. Interestingly, we could detect evidence of microevolutionary changes consistent with previously documented macroevolutionary patterns, such as changes in expression consistent with previously established patterns of sexual dimorphism, an increase in the expression of metabolic genes related to mito-nuclear conflict and evidence that dosage compensation effects can be rapidly altered. These results confirm the importance of the X in the evolution of sexual dimorphism and as a source for sexually antagonistic genetic variation and demonstrate that experimental evolution can be a fruitful method for testing theories of sex chromosome evolution.
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| 4. |
- Abbott, Jessica, et al.
(författare)
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Phenotypic and genetic variation in emergence and development time of a trimorphic damselfly
- 2005
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 18:6, s. 1464-1470
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Tidskriftsartikel (refereegranskat)abstract
- Although colour polymorphisms in adult organisms of many taxa are often adaptive in the context of sexual selection or predation, genetic correlations between colour and other phenotypic traits expressed early in ontogeny could also play an important role in polymorphic systems. We studied phenotypic and genetic variation in development time among female colour morphs in the polymorphic damselfly Ischnura elegans in the field and by raising larvae in a common laboratory environment. In the field, the three different female morphs emerged at different times. Among laboratory-raised families, we found evidence of a significant correlation between maternal morph and larval development time in both sexes. This suggests that the phenotypic correlation between morph and emergence time in the field has a parallel in a genetic correlation between maternal colour and offspring development time. Maternal colour morph frequencies could thus potentially change as correlated responses to selection on larval emergence dates. The similar genetic correlation in male offspring suggests that sex-limitation in this system is incomplete, which may lead to an ontogenetic sexual conflict between selection for early male emergence (protandry) and emergence times associated with maternal morph.
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| 5. |
- Abbott, R., et al.
(författare)
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Hybridization and speciation
- 2013
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26:2, s. 229-246
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Forskningsöversikt (refereegranskat)abstract
- Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near-instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky-Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock-on effects on speciation both within and outside regions of hybridization.
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| 6. |
- Abrahamczyk, S., et al.
(författare)
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Pollinator adaptation and the evolution of floral nectar sugar composition
- 2017
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 30:1, s. 112-127
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Tidskriftsartikel (refereegranskat)abstract
- A long-standing debate concerns whether nectar sugar composition evolves as an adaptation to pollinator dietary requirements or whether it is 'phylogenetically constrained'. Here, we use a modelling approach to evaluate the hypothesis that nectar sucrose proportion (NSP) is an adaptation to pollinators. We analyse similar to 2100 species of asterids, spanning several plant families and pollinator groups (PGs), and show that the hypothesis of adaptation cannot be rejected: NSP evolves towards two optimal values, high NSP for specialist-pollinated and low NSP for generalist-pollinated plants. However, the inferred adaptive process is weak, suggesting that adaptation to PG only provides a partial explanation for how nectar evolves. Additional factors are therefore needed to fully explain nectar evolution, and we suggest that future studies might incorporate floral shape and size and the abiotic environment into the analytical framework. Further, we show that NSP and PG evolution are correlated - in a manner dictated by pollinator behaviour. This contrasts with the view that a plant necessarily has to adapt its nectar composition to ensure pollination but rather suggests that pollinators adapt their foraging behaviour or dietary requirements to the nectar sugar composition presented by the plants. Finally, we document unexpectedly sucrose-poor nectar in some specialized nectarivorous bird-pollinated plants from the Old World, which might represent an overlooked form of pollinator deception. Thus, our broad study provides several new insights into how nectar evolves and we conclude by discussing why maintaining the conceptual dichotomy between adaptation and constraint might be unhelpful for advancing this field.
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| 7. |
- Adolfsson, S, et al.
(författare)
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The spread of apomixis and its effect on resident genetic variation
- 2007
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Ingår i: Journal of evolutionary biology. - : Wiley. - 1420-9101 .- 1010-061X. ; 20:5, s. 1933-1940
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Tidskriftsartikel (refereegranskat)abstract
- In a simulation model we investigated how much of the initial genetic variation that is retained in a population after a dominant mutation has brought apomixis to fixation in it. A marker allele associated with the apomixis mutation is generally retained after the fixation of apomixis, particularly if the two alleles are closely linked. The spread of asexuality, however, normally leads to almost no loss of genetic variation, neither with respect to cytotypes nor with respect to genotypes. This holds for large populations and apomixis mutants with strong pollen production. In smaller populations, and with apomicts with reduced pollen production, the outcome is more variable, ranging from no genetic variation retained to only weakly reduced variability compared with the initial state. These results help explain the high genetic variability in many apomicts. They also imply that natural selection will have many genotypes to act on even after the spread of apomixis.
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| 8. |
- Ah-King, Malin, 1973-, et al.
(författare)
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The influence of territoriality and mating system for the evolution of male care, a phylogenetic study on fish
- 2005
-
Ingår i: Journal of Evolutionary Biology. - 1010-061X .- 1420-9101.
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Tidskriftsartikel (refereegranskat)abstract
- Evolution of male care is still poorly understood. Using phylogeneticallymatched-pairs comparisons we tested for effects of territoriality and matingsystem on male care evolution in fish. All origins of male care were found inpair-spawning species (with or without additional males such as sneakers) andnone were found in group-spawning species. However, excluding groupspawners, male care originated equally often in pair-spawning species withadditional males as in strict pair-spawning species. Evolution of male care wasalso significantly related to territoriality. Yet, most pair-spawning taxa withmale care are also territorial, making their relative influence difficult toseparate. Furthermore, territoriality also occurs in group-spawning species.Hence, territoriality is not sufficient for male care to evolve. Rather, we arguethat it is the combination of territoriality and pair spawning with sequentialpolygyny that favours the evolution of male care, and we discuss our results inrelation to paternity assurance and sexual selection.
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| 9. |
- Ah-King, M., et al.
(författare)
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The influence of territoriality and mating system on the evolution of male care: a phylogenetic study on fish.
- 2005
-
Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 18:2, s. 371-382
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Tidskriftsartikel (refereegranskat)abstract
- Evolution of male care is still poorly understood. Using phylogenetically matched-pairs comparisons we tested for effects of territoriality and mating system on male care evolution in fish. All origins of male care were found in pair-spawning species (with or without additional males such as sneakers) and none were found in group-spawning species. However, excluding group spawners, male care originated equally often in pair-spawning species with additional males as in strict pair-spawning species. Evolution of male care was also significantly related to territoriality. Yet, most pair-spawning taxa with male care are also territorial, making their relative influence difficult to separate. Furthermore, territoriality also occurs in group-spawning species. Hence, territoriality is not sufficient for male care to evolve. Rather, we argue that it is the combination of territoriality and pair spawning with sequential polygyny that favours the evolution of male care, and we discuss our results in relation to paternity assurance and sexual selection.
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| 10. |
- Akiyama, Reiko, et al.
(författare)
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Conflicting selection on the timing of germination in a natural population of Arabidopsis thaliana
- 2014
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 27:1, s. 193-199
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Tidskriftsartikel (refereegranskat)abstract
- The timing of germination is a key life-history trait that may strongly influence plant fitness and that sets the stage for selection on traits expressed later in the life cycle. In seasonal environments, the period favourable for germination and the total length of the growing season are limited. The optimal timing of germination may therefore be governed by conflicting selection through survival and fecundity. We conducted a field experiment to examine the effects of timing of germination on survival, fecundity and overall fitness in a natural population of the annual herb Arabidopsis thaliana in north-central Sweden. Seedlings were transplanted at three different times in late summer and in autumn covering the period of seed germination in the study population. Early germination was associated with low seedling survival, but also with high survival and fecundity among established plants. The advantages of germinating early more than balanced the disadvantage and selection favoured early germination. The results suggest that low survival among early germinating seeds is the main force opposing the evolution of earlier germination and that the optimal timing of germination should vary in space and time as a function of the direction and strength of selection acting during different life-history stages.
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| 11. |
- Alho, J. S., et al.
(författare)
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Allen's rule revisited : quantitative genetics of extremity length in the common frog along a latitudinal gradient
- 2011
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 24:1, s. 59-70
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Tidskriftsartikel (refereegranskat)abstract
- Ecogeographical rules linking climate to morphology have gained renewed interest because of climate change. Yet few studies have evaluated to what extent geographical trends ascribed to these rules have a genetic, rather than environmentally determined, basis. This applies especially to Allen's rule, which states that the relative extremity length decreases with increasing latitude. We studied leg length in the common frog (Rana temporaria) along a 1500 km latitudinal gradient utilizing wild and common garden data. In the wild, the body size-corrected femur and tibia lengths did not conform to Allen's rule but peaked at mid-latitudes. However, the ratio of femur to tibia length increased in the north, and the common garden data revealed a genetic cline consistent with Allen's rule in some trait and treatment combinations. While selection may have shortened the leg length in the north, the genetic trend seems to be partially masked by environmental effects.
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| 12. |
- Alström, Per
(författare)
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Recent northward range expansion promotes song evolution in a passerine bird, the Light-vented Bulbul
- 2013
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26, s. 867-877
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Tidskriftsartikel (refereegranskat)abstract
- In common with human speech, song is culturally inherited in oscine passerine birds (songbirds'). Intraspecific divergence in birdsong, such as development of local dialects, might be an important early step in the speciation process. It is therefore vital to understand how songs diverge, especially in founding populations. The northward expansion of the Light-vented Bulbul Pycnonotus sinensis (J. F. Gmelin, 1789) into north China in the last 30years provides an excellent opportunity to study birdsong evolution. We compared similar to 4400 songs from newly established northern populations with similar to 2900 songs from southern populations to evaluate song divergence after recent expansion. The total pool of syllables and especially song types was considerably smaller in the north than in the south, indicating founder effects' in the new population. The ancestral pattern of mosaic song dialects changed into a pattern of wide geographical sharing of a few song types and syllables, likely the result of fewer geographical barriers to meme flow', and the recent spread across a large area in the north. Our results suggest that song evolution and vocal trait shifts can arise rapidly after range expansion, and that in the Light-vented Bulbul founder effects', geographical isolation, and recent rapid expansions played important roles in the evolution of song dialects.
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| 13. |
- Amcoff, Mirjam, et al.
(författare)
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Evolution of egg dummies in Tanganyikan cichlid fishes : the roles of parental care and sexual selection
- 2013
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26:11, s. 2369-2382
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Forskningsöversikt (refereegranskat)abstract
- Sexual selection has been suggested to be an important driver of speciation in cichlid fishes of the Great Lakes of Africa, and the presence of male egg dummies is proposed to have played a key role. Here, we investigate how mouthbrooding and egg dummies have evolved in Tanganyikan cichlids, the lineage which seeded the other African radiations, with a special emphasis on the egg dummies. Using modern phylogenetic comparative analyses and a phylogeny including 86% of the 200 described species, we provide formal evidence demonstrating correlated evolution between mouthbrooding and egg dummies in Tanganyikan cichlids. These results concur with existing evidence, suggesting that egg dummies have evolved through sensory exploitation. We also demonstrate that there is a strong evolutionary correlation between the presence of egg dummies and both pre- and post-copulatory sexual selection. Moreover, egg dummy evolution was contingent on the intensity of pre- and post-copulatory sexual selection in Tanganyikan cichlids. In sum, our results provide evidence supporting the hypothesis of egg dummies evolving through sensory exploitation and highlight the role of sexual selection in favouring the evolution and maintenance of this trait.
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| 14. |
- Andersson, Staffan, 1959, et al.
(författare)
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Effects of egg yolk testosterone on growth and immunity in a precocial bird
- 2004
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X. ; 17:3, s. 501-505
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Tidskriftsartikel (refereegranskat)abstract
- In oviparous vertebrates, maternal steroid allocation to eggs can have important fitness consequences for the offspring. However, elevated testosterone levels are not only associated with beneficial postnatal effects, such as enhanced growth and high social status, but may also entail costs by suppressing the immune system. In this study, testosterone levels in eggs of Chinese painted quail (Coturnix chinensis) were experimentally manipulated to evaluate its effects on growth and immunocompetence. Testosterone did not affect embryonic development, body size or growth during the first 20 days. However, elevated testosterone levels during embryonic development were immunosuppressive for chicks with inherently higher growth rate. Adaptive scenarios where only beneficial effects of increased testosterone levels are considered may therefore need to be re-evaluated.
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| 15. |
- Andersson, Stefan, et al.
(författare)
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Paternal effects on seed germination: a barrier to the genetic assimilation of an endemic plant taxon?
- 2008
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Ingår i: Journal of evolutionary biology. - : Wiley. - 1420-9101 .- 1010-061X. ; 21:5, s. 1408-1417
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Tidskriftsartikel (refereegranskat)abstract
- We used a crossing experiment to investigate post-zygotic barriers that might limit introgression between a pair of closely-related, gynodioecious plant species - the widespread weed Silene vulgaris and the local Swedish endemic S. uniflora ssp. petraea. The study not only considered the effects of hybridization on conventionally-used (primary) fitness components such as seed set and progeny survival, but also provided a test for the effects of interspecific hybridization on characters with more subtle or habitat-specific effects on fitness. We detected highly significant paternal effects on seed germination properties, with the germination characteristics of hybrid seed resembling those of the species that served as the pollen donor. These paternal effects on germination represent a potentially strong barrier to interspecific introgression in the two species' natural habitats, where an inappropriate germination response in the habitat of the maternal parent may lead to the failure of seedling establishment. Interspecific crosses had weak or variable effects on progeny survival, flowering and sex ratio, but these effects could not be interpreted in terms of barriers to introgression. Our results indicate that nuclear restorers in S. vulgaris have the capacity to suppress cytoplasmic male-sterility genes in its endemic congener.
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| 16. |
- Appelgren, A., et al.
(författare)
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Relative fitness of a generalist parasite on two alternative hosts : a cross-infestation experiment to test host specialization of the hen flea Ceratophyllus gallinae (Schrank)
- 2016
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 29:5, s. 1091-1101
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Tidskriftsartikel (refereegranskat)abstract
- Host range is a key element of a parasite's ecology and evolution and can vary greatly depending on spatial scale. Generalist parasites frequently show local population structure in relation to alternative sympatric hosts (i.e. host races) and may thus be specialists at local scales. Here, we investigated local population specialization of a common avian nest-based parasite, the hen flea Ceratophyllus gallinae (Schrank), exploiting two abundant host species that share the same breeding sites, the great tit Parus major (Linnaeus) and the collared flycatcher Ficedula albicollis (Temminck). We performed a cross-infestation experiment of fleas between the two host species in two distinct study areas during a single breeding season and recorded the reproductive success of both hosts and parasites. In the following year, hosts were monitored again to assess the long-term impact of cross-infestation. Our results partly support the local specialization hypothesis: in great tit nests, tit fleas caused higher damage to their hosts than flycatcher fleas, and in collared flycatcher nests, flycatcher fleas had a faster larval development rates than tit fleas. However, these results were significant in only one of the two studied areas, suggesting that the location and history of the host population can modulate the specialization process. Caution is therefore called for when interpreting single location studies. More generally, our results emphasize the need to explicitly account for host diversity in order to understand the population ecology and evolutionary trajectory of generalist parasites.
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| 17. |
- Arnqvist, Göran, et al.
(författare)
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Population differentiation in the swordtail characin (Corynopoma riisei) : a role for sensory drive?
- 2010
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 23:9, s. 1907-1918
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Forskningsöversikt (refereegranskat)abstract
- Sensory drive, where the efficacy of a sexual signal depends on the environment in which it is employed, is a potential mechanism behind divergent evolution of secondary sexual traits. Male swordtail characins are equipped with a narrow and transparent extension of the gill cover with a flag-like structure at its tip. This opercular flag mimics a prey item and is employed by males as a 'lure' to attract the attention of females during mating attempts. We conducted a study of genetic and morphological differentiation across swordtail characin populations throughout their native range in Trinidad. The morphology of the opercular flag varied across populations and several aspects of this variation match the predicted hallmarks of sensory drive. First, morphological differentiation of the flag across populations was unrelated to genetic similarity at neutral genetic markers. Second, the shape of the flag covaried with those aspects of body shape that should reflect adaptation to different feeding regimes. Third, and most importantly, the shape of the flag covaried across populations with those environmental characteristics that should most closely reflect differences in local prey abundance. Overall, our results are consistent with a scenario where the evolution of this male sexual signal tracks food-related shifts in female sensory biases across populations, thus providing at least provisional support for a role for sensory drive in population differentiation.
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| 18. |
- Baur, Julian, et al.
(författare)
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Intraspecific mating system evolution and its effect on complex male secondary sexual traits : Does male–male competition increase selection on size or shape?
- 2020
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Ingår i: Journal of Evolutionary Biology. - : John Wiley & Sons. - 1010-061X .- 1420-9101. ; 33:3, s. 297-308
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Tidskriftsartikel (refereegranskat)abstract
- Sexual selection is generally held responsible for the exceptional diversity in secondary sexual traits in animals. Mating system evolution is therefore expected to profoundly affect the covariation between secondary sexual traits and mating success. Whereas there is such evidence at the interspecific level, data within species remain scarce. We here investigate sexual selection acting on the exaggerated male fore femur and the male wing in the common and widespread dung flies Sepsis punctum and S. neocynipsea (Diptera: Sepsidae). Both species exhibit intraspecific differences in mating systems and variation in sexual size dimorphism (SSD) across continents that correlates with the extent of male–male competition. We predicted that populations subject to increased male–male competition will experience stronger directional selection on the sexually dimorphic male foreleg. Our results suggest that fore femur size, width and shape were indeed positively associated with mating success in populations with male‐biased SSD in both species, which was not evident in conspecific populations with female‐biased SSD. However, this was also the case for wing size and shape, a trait often assumed to be primarily under natural selection. After correcting for selection on overall body size by accounting for allometric scaling, we found little evidence for independent selection on any of these size or shape traits in legs or wings, irrespective of the mating system. Sexual dimorphism and (foreleg) trait exaggeration is therefore unlikely to be driven by direct precopulatory sexual selection, but more so by selection on overall size or possibly selection on allometric scaling.
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| 19. |
- Bengtsson, Bengt Olle
(författare)
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Genetic variation in organisms with sexual and asexual reproduction
- 2003
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Ingår i: Journal of evolutionary biology. - : Wiley. - 1420-9101 .- 1010-061X. ; 16:2, s. 189-199
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Tidskriftsartikel (refereegranskat)abstract
- The genetic variation in a partially asexual organism is investigated by two models suited for different time scales. Only selectively neutral variation is considered. Model 1 shows, by the use of a coalescence argument, that three sexually derived individuals per generation are sufficient to give a population the same pattern of allelic variation as found in fully sexually reproducing organisms. With less than one sexual event every third generation, the characteristic pattern expected for asexual organisms appear, with strong allelic divergence between the gene copies in individuals. At intermediary levels of sexuality, a complex situation reigns. The pair-wise allelic divergence under partial sexuality exceeds, however, always the corresponding value under full sexuality. These results apply to large populations with stable reproductive systems. In a more general framework, Model 2 shows that a small number of sexual individuals per generation is sufficient to make an apparently asexual population highly genotypically variable. The time scale in terms of generations needed to produce this effect is given by the population size and the inverse of the rate of sexuality.
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| 20. |
- Bengtsson, Bengt Olle, et al.
(författare)
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The balance between sexual and asexual reproduction in plants living in variable environments
- 2000
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Ingår i: Journal of evolutionary biology. - : Wiley. - 1420-9101 .- 1010-061X. ; 13:3, s. 415-422
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Tidskriftsartikel (refereegranskat)abstract
- The balance between sexual and asexual propagule production is studied in an evolutionary model where plants produce the two kinds of propagules in genetically determined proportions. The male function of plants producing asexual propagules can be varied, and the sexual and asexual propagules carry different probabilities to turn into new reproductive individuals. These fitnesses may vary over years. The evolution of the population’s reproductive system is studied assuming modifier alleles with small effects. In this setting a balanced, mixed reproductive system can evolve, but only if the difference in fitness between the sexual and asexual propagules varies over years. When the two kinds of propagules are very similar to each other, as is often the case with sexual and asexual seed formation, evolution will tend towards a state dominated by the one or the other reproductive system.
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| 21. |
- Bensch, Hanna, et al.
(författare)
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Environmental effects rather than relatedness determine gut microbiome similarity in a social mammal
- 2023
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Ingår i: Journal of Evolutionary Biology. - : John Wiley & Sons. - 1010-061X .- 1420-9101. ; 36:12, s. 1753-1760
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Tidskriftsartikel (refereegranskat)abstract
- In social species, group members commonly show substantial similarity in gut microbiome composition. Such similarities have been hypothesized to arise either by shared environmental effects or by host relatedness. However, disentangling these factors is difficult, because group members are often related, and social groups typically share similar environmental conditions. In this study, we conducted a cross-foster experiment under controlled laboratory conditions in group-living Damaraland mole-rats (Fukomys damarensis) and used 16S amplicon sequencing to disentangle the effects of the environment and relatedness on gut microbiome similarity and diversity. Our results show that a shared environment is the main factor explaining gut microbiome similarity, overshadowing any effect of host relatedness. Together with studies in wild animal populations, our results suggest that among conspecifics environmental factors are more powerful drivers of gut microbiome composition similarity than host genetics.
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| 22. |
- Berdan, Emma L, 1983, et al.
(författare)
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Genomic landscape of reproductive isolation in Lucania killifish: The role of sex loci and salinity
- 2021
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 34:1, s. 157-174
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Tidskriftsartikel (refereegranskat)abstract
- Adaptation to different environments can directly and indirectly generate reproductive isolation between species. Bluefin killifish (Lucania goodei) and rainwater killifish (L. parva) are sister species that have diverged across a salinity gradient and are reproductively isolated by habitat, behavioural, extrinsic and intrinsic post-zygotic isolation. We asked if salinity adaptation contributes indirectly to other forms of reproductive isolation via linked selection and hypothesized that low recombination regions, such as sex chromosomes or chromosomal rearrangements, might facilitate this process. We conducted QTL mapping in backcrosses between L. parva and L. goodei to explore the genetic architecture of salinity tolerance, behavioural isolation and intrinsic isolation. We mapped traits relative to a chromosome that has undergone a centric fusion in L. parva (relative to L. goodei). We found that the sex locus appears to be male determining (XX-XY), was located on the fused chromosome and was implicated in intrinsic isolation. QTL associated with salinity tolerance were spread across the genome and did not overly co-localize with regions associated with behavioural or intrinsic isolation. This preliminary analysis of the genetic architecture of reproductive isolation between Lucania species does not support the hypothesis that divergent natural selection for salinity tolerance led to behavioural and intrinsic isolation as a by-product. Combined with previous studies in this system, our work suggests that adaptation as a function of salinity contributes to habitat isolation and that reinforcement may have contributed to the evolution of behavioural isolation instead, possibly facilitated by linkage between behavioural isolation and intrinsic isolation loci on the fused chromosome.
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| 23. |
- Berdan, Emma L, 1983, et al.
(författare)
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How chromosomal inversions reorient the evolutionary process
- 2023
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Ingår i: Journal of Evolutionary Biology. - 1010-061X .- 1420-9101. ; 36:12, s. 1761-1782
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Forskningsöversikt (refereegranskat)abstract
- Inversions are structural mutations that reverse the sequence of a chromosome seg-ment and reduce the effective rate of recombination in the heterozygous state. They play a major role in adaptation, as well as in other evolutionary processes such as spe-ciation. Although inversions have been studied since the 1920s, they remain difficult to investigate because the reduced recombination conferred by them strengthens the effects of drift and hitchhiking, which in turn can obscure signatures of selection. Nonetheless, numerous inversions have been found to be under selection. Given re-cent advances in population genetic theory and empirical study, here we review how different mechanisms of selection affect the evolution of inversions. A key difference between inversions and other mutations, such as single nucleotide variants, is that the fitness of an inversion may be affected by a larger number of frequently interacting processes. This considerably complicates the analysis of the causes underlying the evolution of inversions. We discuss the extent to which these mechanisms can be disentangled, and by which approach.
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| 24. |
- Berg, LM, et al.
(författare)
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Neutral genetic differentiation in an island model with cyclical parthenogenesis
- 2000
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Ingår i: JOURNAL OF EVOLUTIONARY BIOLOGY. - 1010-061X. ; 13:3, s. 488-494
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Tidskriftsartikel (refereegranskat)abstract
- Unusually high levels of genetic differentiation are often observed between populations of Daphnia (Crustacea: Cladocera) and other cladocerans. Selection and departure from migration-mutation-drift equilibrium have been invoked to explain this fact. Howe
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| 25. |
- Berger, David, et al.
(författare)
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Experimental evolution for generalists and specialists reveals multivariate genetic constraints on thermal reaction norms
- 2014
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 27:9, s. 1975-1989
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Tidskriftsartikel (refereegranskat)abstract
- Theory predicts the emergence of generalists in variable environments and antagonistic pleiotropy to favour specialists in constant environments, but empirical data seldom support such generalist-specialist trade-offs. We selected for generalists and specialists in the dung fly Sepsis punctum (Diptera: Sepsidae) under conditions that we predicted would reveal antagonistic pleiotropy and multivariate trade-offs underlying thermal reaction norms for juvenile development. We performed replicated laboratory evolution using four treatments: adaptation at a hot (31 degrees C) or a cold (15 degrees C) temperature, or under regimes fluctuating between these temperatures, either within or between generations. After 20 generations, we assessed parental effects and genetic responses of thermal reaction norms for three correlated life-history traits: size at maturity, juvenile growth rate and juvenile survival. We find evidence for antagonistic pleiotropy for performance at hot and cold temperatures, and a temperature-mediated trade-off between juvenile survival and size at maturity, suggesting that trade-offs associated with environmental tolerance can arise via intensified evolutionary compromises between genetically correlated traits. However, despite this antagonistic pleiotropy, we found no support for the evolution of increased thermal tolerance breadth at the expense of reduced maximal performance, suggesting low genetic variance in the generalist-specialist dimension.
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