共查询到20条相似文献，搜索用时 15 毫秒
1.
Timothy D. Weaver 《Ecology and evolution》2016,6(21):7783-7786
Comparisons of to can provide insights into the evolutionary processes that lead to differentiation, or lack thereof, among the phenotypes of different groups (e.g., populations, species), and these comparisons have been performed on a variety of taxa, including humans. Here, I show that for neutrally evolving (i.e., by genetic drift, mutation, and gene flow alone) quantitative characters, the two commonly used estimators have somewhat different interpretations in terms of coalescence times, particularly when the number of groups that have been sampled is small. A similar situation occurs for estimators. Consequently, when observations come from only a small number of groups, which is not an unusual situation, it is important to match estimators appropriately when comparing to . 相似文献
2.
David N. Fisher Alastair J. Wilson Stan Boutin Ben Dantzer Jeffrey E. Lane David W. Coltman Jamie C. Gorrell Andrew G. McAdam 《Journal of evolutionary biology》2019,32(6):559-571
Organisms can affect one another's phenotypes when they socially interact. Indirect genetic effects occur when an individual's phenotype is affected by genes expressed in another individual. These heritable effects can enhance or reduce adaptive potential, thereby accelerating or reversing evolutionary change. Quantifying these social effects is therefore crucial for our understanding of evolution, yet estimates of indirect genetic effects in wild animals are limited to dyadic interactions. We estimated indirect phenotypic and genetic effects, and their covariance with direct effects, for the date of spring breeding in North American red squirrels (Tamiasciurus hudsonicus) living in an array of territories of varying spatial proximity. Additionally, we estimated indirect effects and the strength of selection at low and high population densities. Social effects of neighbours on the date of spring breeding were different from zero at high population densities but not at low population densities. Indirect phenotypic effects accounted for a larger amount of variation in the date of breeding than differences attributable to the among‐individual variance, suggesting social interactions are important for determining breeding dates. The genetic component to these indirect effects was however not statistically significant. We therefore showcase a powerful and flexible method that will allow researchers working in organisms with a range of social systems to estimate indirect phenotypic and genetic effects, and demonstrate the degree to which social interactions can influence phenotypes, even in a solitary species. 相似文献
3.
Genome scans have been an important approach for discovering historical signatures of selection in both model and nonmodel species. An exciting new experimental design for genome scans is to measure the change in allele frequency before and after contemporary selection within a generation, from a single population. The most widely‐used methods, however, have two major limitations: they are based on testing one locus at a time, and they only have power to uncover loci that have evolved under relatively strong selection. On the other hand, complex quantitative traits are common in nature and are caused by several loci of small effect. Selection on a quantitative trait at the phenotypic level is predicted to be accompanied by subtle allele frequency changes in many loci that covary (a polygenic soft sweep), rather than a large, single‐effect allele (a selective sweep). In this issue of Molecular Ecology, Bourret et al. (2014) measure the contemporary response to natural selection across the genome in multiple cohorts of Atlantic salmon during their first year at sea. They introduce a multilocus framework based on groups of markers that covary in their genotypic distribution. While the traditional, single‐locus approach did not find evidence for repeated patterns of selection, the multivariate approach found that a group of covarying SNPs was selected for in different cohorts at one site. Their multilocus framework has potential to be a more fruitful approach for uncovering the genomic basis of adaptation in quantitative traits, although caution should be applied as the framework has yet to be validated with simulated data. 相似文献
4.
T. P. Gosden J. R. Thomson M. W. Blows A. Schaul S. F. Chenoweth 《Journal of evolutionary biology》2016,29(6):1278-1283
In accordance with the consensus that sexual selection is responsible for the rapid evolution of display traits on macroevolutionary scales, microevolutionary studies suggest sexual selection is a widespread and often strong form of directional selection in nature. However, empirical evidence for the contemporary evolution of sexually selected traits via sexual rather than natural selection remains weak. In this study, we used a novel application of quantitative genetic breeding designs to test for a genetic response to sexual selection on eight chemical display traits from a field population of the fly, Drosophila serrata. Using our quantitative genetic approach, we were able to detect a genetically based difference in means between groups of males descended from fathers who had either successfully sired offspring or were randomly collected from the same wild population for one of these display traits, the diene (Z,Z)‐5,9‐C27 : 2. Our experimental results, in combination with previous laboratory studies on this system, suggest that both natural and sexual selection may be influencing the evolutionary trajectories of these traits in nature, limiting the capacity for a contemporary evolutionary response. 相似文献
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Understanding the genetic diversity and structure of invasive pathogens in source and in introduced areas is crucial to the revelation of hidden biological features of an organism, to the reconstruction of the course of invasions and to the establishment of effective control measures. Hymenoscyphus pseudoalbidus (anamorph: Chalara fraxinea) is an invasive and highly destructive fungal pathogen found on common ash Fraxinus excelsior in Europe and is native to East Asia. To gain insights into its dispersal mechanisms and history of invasion, we used microsatellite markers and characterized the genetic structure and diversity of H. pseudoalbidus populations at three spatial levels: (i) between Europe and Japan, (ii) in Europe and (iii) at the epidemic's front in Switzerland. Phylogenetic and network analysis demonstrated that individuals from both regions are conspecific. However, populations from Japan harboured a higher genetic diversity and were genetically differentiated from European ones. No evident population structure was found among the 1208 European strains using Bayesian and multivariate clustering analysis. Only the distribution of genetic diversity in space, pairwise population differentiation (GST) and the spatial analysis of principal components revealed a faint geographical pattern around Europe. A significant allele deficiency in most European populations pointed to a recent genetic bottleneck, whereas no pattern of isolation by distance was found. Our data suggest that H. pseudoalbidus was introduced just once by at least two individuals. The potential source region of H. pseudoalbidus is vast, and further investigations are required for a more accurate localization of the source population. 相似文献
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Aapo Kahilainen Inka Keränen Katja Kuitunen Janne S. Kotiaho K. Emily Knott 《Molecular ecology》2014,23(20):4976-4988
Spatial genetic structure (SGS) is largely determined by colonization history, landscape and ecological characteristics of the species. Therefore, sympatric and ecologically similar species are expected to exhibit similar SGSs, potentially enabling prediction of the SGS of one species from that of another. On the other hand, due to interspecific interactions, ecologically similar species could have different SGSs. We explored the SGSs of the closely related Calopteryx splendens and Calopteryx virgo within Finland and related the genetic patterns to characteristics of the sampling localities. We observed different SGSs for the two species. Genetic differentiation even within short distances in C. splendens suggests genetic drift as an important driver. However, we also observed indication of previous gene flow (revealed by a negative relationship between genetic differentiation and increasing potential connectivity of the landscape). Interestingly, genetic diversity of C. splendens was negatively related to density of C. virgo, suggesting that interspecific interactions influence the SGS of C. splendens. In contrast, genetic differentiation between C. virgo subpopulations was low and only exhibited relationships with latitude, pointing to high gene flow, colonization history and range margin effects as the drivers of SGS. The different SGSs of the two ecologically similar species caution indirect inferences of SGS based on ecologically similar surrogate species. 相似文献
8.
Erin E. Collins John S. Hargrove Thomas A. Delomas Shawn R. Narum 《Ecology and evolution》2020,10(17):9486-9502
Fish migrations are energetically costly, especially when moving between freshwater and saltwater, but are a viable strategy for Pacific salmon and trout (Oncorhynchus spp.) due to the advantageous resources available at various life stages. Anadromous steelhead (O. mykiss) migrate vast distances and exhibit variation for adult migration phenotypes that have a genetic basis at candidate genes known as greb1L and rock1. We examined the distribution of genetic variation at 13 candidate markers spanning greb1L, intergenic, and rock1 regions versus 226 neutral markers for 113 populations (n = 9,471) of steelhead from inland and coastal lineages in the Columbia River. Patterns of population structure with neutral markers reflected genetic similarity by geographic region as demonstrated in previous studies, but candidate markers clustered populations by genetic variation associated with adult migration timing. Mature alleles for late migration had the highest frequency overall in steelhead populations throughout the Columbia River, with only 9 of 113 populations that had a higher frequency of premature alleles for early migration. While a single haplotype block was evident for the coastal lineage, we identified multiple haplotype blocks for the inland lineage. The inland lineage had one haplotype block that corresponded to candidate markers within the greb1L gene and immediately upstream in the intergenic region, and the second block only contained candidate markers from the intergenic region. Haplotype frequencies had similar patterns of geographic distribution as single markers, but there were distinct differences in frequency between the two haplotype blocks for the inland lineage. This may represent multiple recombination events that differed between lineages where phenotypic differences exist between freshwater entry versus arrival timing as indicated by Micheletti et al. (2018a). Redundancy analyses were used to model environmental effects on allelic frequencies of candidate markers, and significant variables were migration distance, temperature, isothermality, and annual precipitation. This study improves our understanding of the spatial distribution of genetic variation underlying adult migration timing in steelhead as well as associated environmental factors and has direct conservation and management implications. 相似文献
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Fábio M. Alves Ângela L. B. Sartori Maria I. Zucchi Ana M. G. Azevedo‐Tozzi Evandro V. Tambarussi Alessandro Alves‐Pereira Anete P. de Souza 《Ecology and evolution》2018,8(13):6558-6574
The Gran Chaco is the largest continuous region of the South American dry forest, spanning Argentina, Paraguay, Bolivia, and Brazil. Prosopis rubriflora and Prosopis ruscifolia are typical tree species of chaquenian area forests, which have been subjected to continuous fragmentation caused by cattle raising. This study evaluated P. rubriflora and P. ruscifolia in areas with varying levels of disturbance. We investigated the contemporary genetic diversities of both species in areas with distinct anthropogenic disturbances. Even with a lower heterozygote frequency, disturbed areas can provide important storage for alleles, allowing the maintenance of diversity. The genetic diversity of P. rubriflora was surprisingly similar to that of P. ruscifolia (He = 0.59 and He = 0.60, respectively) even with very different distribution ranges of both species. However, P. ruscifolia exhibited a higher intrapopulation fixation index than P. rubriflora. P. rubriflora showed evidence of bottlenecking in 64% of the sampled areas, while P. ruscifolia showed such evidence in 36% of the sampled areas. Additionally, P. rubriflora had two distinct populations due to its disjunctive geographic distribution, whereas P. ruscifolia had a single population that exhibited few signs of population structure in some areas, possibly due to the main pollinators presenting a short range of dispersion. Our results suggest that 42 Chaco areas should be conserved to retain the minimum of 500 individuals necessary to maintain genetic diversity for 100–1,000 generations. This study improves our understanding of these two Prosopis species and provides information for the conservation of their genetic diversities. 相似文献
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Pierre de Villemereuil Alexis Rutschmann John G. Ewen Anna W. Santure Patricia Brekke 《Evolutionary Applications》2019,12(3):482-497
Many bird species have been observed shifting their laying date to earlier in the year in response to climate change. However, the vast majority of these studies were performed on non‐threatened species, less impacted by reduced genetic diversity (which is expected to limit evolutionary response) as a consequence of genetic bottlenecks, drift and population isolation. Here, we study the relationship between lay date and fitness, as well as its genetic basis, to understand the evolutionary constraints on phenology faced by threatened species using a recently reintroduced population of the endangered New Zealand passerine, the hihi (Notiomystis cincta). A large discrepancy between the optimal laying date and the mode of laying date creates a strong selection differential of −11.24. The impact of this discrepancy on fitness is principally mediated through survival of offspring from hatchling to fledgling. This discrepancy does not seem to arise from a difference in female quality or a trade‐off with lifetime breeding success. We find that start of breeding season depends on female age and average temperature prior to the breeding season. Laying date is not found to be significantly heritable. Overall, our research suggests that this discrepancy is a burden on hihi fitness, which will not be resolved through evolution or phenotypic plasticity. More generally, these results show that threatened species introduced to restored habitats might lack adaptive potential and plasticity to adjust their phenology to their new environment. This constraint is also likely to limit their ability to face future challenges, including climate change. 相似文献
11.
Studying the genetic architecture of sexual traits provides insight into the rate and direction at which traits can respond to selection. Traits associated with few loci and limited genetic and phenotypic constraints tend to evolve at high rates typically observed for secondary sexual characters. Here, we examined the genetic architecture of song traits and female song preferences in the field crickets Gryllus rubens and Gryllus texensis. Song and preference data were collected from both species and interspecific F1 and F2 hybrids. We first analysed phenotypic variation to examine interspecific differentiation and trait distributions in parental and hybrid generations. Then, the relative contribution of additive and additive‐dominance variation was estimated. Finally, phenotypic variance–covariance ( P ) matrices were estimated to evaluate the multivariate phenotype available for selection. Song traits and preferences had unimodal trait distributions, and hybrid offspring were intermediate with respect to the parents. We uncovered additive and dominance variation in song traits and preferences. For two song traits, we found evidence for X‐linked inheritance. On the one hand, the observed genetic architecture does not suggest rapid divergence, although sex linkage may have allowed for somewhat higher evolutionary rates. On the other hand, P matrices revealed that multivariate variation in song traits aligned with major dimensions in song preferences, suggesting a strong selection response. We also found strong covariance between the main traits that are sexually selected and traits that are not directly selected by females, providing an explanation for the striking multivariate divergence in male calling songs despite limited divergence in female preferences. 相似文献
12.
Plant–pollinator interactions are thought to be major drivers of floral trait diversity. However, the relative importance of divergent pollinator‐mediated selection vs. neutral processes in floral character evolution has rarely been explored. We tested for adaptive floral trait evolution by comparing differentiation at neutral genetic loci to differentiation at quantitative floral traits in a putative Ipomopsis aggregata hybrid zone. Typical I. aggregata subsp. candida displays slender white tubular flowers that are typical of flowers pollinated by hawkmoths, and subsp. collina displays robust red tubular flowers typical of flowers pollinated by hummingbirds; yet, hybrid flower morphs are abundant across the East Slope of the Colorado Rockies. We estimated genetic differentiation (FST) for nuclear and chloroplast microsatellite loci and used a half‐sib design to calculate quantitative trait divergence (QST) from collection sites across the morphological hybrid zone. We found little evidence for population structure and estimated mean FST to be 0.032. QST values for several floral traits including corolla tube length and width, colour, and nectar volume were large and significantly greater than mean FST. We performed multivariate comparisons of neutral loci to genetic correlations within and between populations and found a strong signal for divergent selection, suggesting that specific combinations of floral display and reward traits may be the targets of selection. Our results show little support for historical subspecies categories, yet floral traits are more diverged than expected due to drift alone. Non‐neutral divergence for multivariate quantitative traits suggests that selection by pollinators is maintaining a correlation between display and reward traits. 相似文献
13.
Bo Xian Jie Shen Weiyang Chen Na Sun Nan Qiao Dongqing Jiang Tao Yu Yongfan Men Zhijun Han Yuhong Pang Matt Kaeberlein Yanyi Huang Jing‐Dong J. Han 《Aging cell》2013,12(3):398-409
Caenorhabditis elegans is a leading model organism for studying the basic mechanisms of aging. Progress has been limited, however, by the lack of an automated system for quantitative analysis of longevity and mean lifespan. To address this barrier, we developed ‘WormFarm’, an integrated microfluidic device for culturing nematodes. Cohorts of 30–50 animals are maintained throughout their lifespan in each of eight separate chambers on a single WormFarm polydimethylsiloxane chip. Design features allow for automated removal of progeny and efficient control of environmental conditions. In addition, we have developed computational algorithms for automated analysis of video footage to quantitate survival and other phenotypes, such as body size and motility. As proof‐of‐principle, we show here that WormFarm successfully recapitulates survival data obtained from a standard plate‐based assay for both RNAi‐mediated and dietary‐induced changes in lifespan. Further, using a fluorescent reporter in conjunction with WormFarm, we report an age‐associated decrease in fluorescent intensity of GFP in transgenic worms expressing GFP tagged with a mitochondrial import signal under the control of the myo‐3 promoter. This marker may therefore serve as a useful biomarker of biological age and aging rate. 相似文献
14.
Marc T. J. Johnson 《Population Ecology》2011,53(1):9-21
In this review, I consider the contribution that common evening primrose (Oenothera biennis) has made towards integrating the ecology, evolution and genetics of species interactions. Oenothera biennis was among the earliest plant models in genetics and cytogenetics and it played an important role in the modern synthesis of evolutionary biology. More recently, population and ecological genetics approaches have provided insight into the patterns of genetic variation within and between populations, and how a combination of abiotic and biotic factors maintain and select on heritable variation within O. biennis populations. From an ecological perspective, field experiments show that genetic variation and evolution within populations can have cascading effects throughout communities. Plant genotype affects the preference and performance of individual arthropod populations, as well as the composition, biomass, total abundance and diversity of arthropod species on plants. A combination of experiments and simulation models show that natural selection on specific plant traits can drive rapid ecological changes in these same community variables. At the patch level, increasing genotypic diversity leads to a greater abundance and diversity of omnivorous and predaceous arthropods, which is also associated with increased biomass and fecundity of plants in genetically diverse patches. Finally, in questioning whether a community genetics perspective is needed in biology, I review several multifactorial experiments which show that plant genotype often explains as much variation in community variables as other ecological factors typically identified as most important in ecology. As a whole, research in the O. biennis system has contributed to a more complete understanding of the dynamic interplay between ecology, evolution and genetics. 相似文献
15.
Serotiny, the retention of seeds in a canopy seed bank until high temperatures cause seeds to be released, is an important life history trait for many woody plants in fire‐prone habitats. Serotiny provides a competitive advantage after fire but increases vulnerability to predispersal seed predation, due to the seeds being retained in clusters in predictable locations for extended periods. This creates opposing selection pressures. Serotiny is favored in areas of high fire frequency, but is selected against by predispersal seed predators. However, predation also selects for cone traits associated with seed defense that could reduce predation on serotinous cones and thereby relax selection against serotiny. This helps explain the elevated defenses in highly serotinous species. However, whether such interactions drive variation in seed defenses within variably serotinous populations has been studied rarely. We investigated the effects of phenotypic selection exerted by red squirrel (Tamiasciurus hudsonicus) predation on Rocky Mountain lodgepole pine (Pinus contorta latifolia) seeds. Squirrels preferentially harvested cones with more and larger seeds, indicating a preference for a higher food reward. We found evidence for stronger selection on trees with serotinous cones, which presumably accounts for the elevated defenses of and lower predation on serotinous compared to non‐serotinous cones. Lower levels of predation on serotinous cones in turn lessen selection against serotiny by squirrels. This has important implications because the frequency of serotiny in lodgepole pine has profound consequences for post‐fire communities and ecosystems widespread in the Rocky Mountains. 相似文献
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Sara Marin Anaïs Gibert Juliette Archambeau Vincent Bonhomme Mylne Lascoste Benoit Pujol 《Molecular ecology》2020,29(16):3010-3021
Phenotypic divergence among natural populations can be explained by natural selection or by neutral processes such as drift. Many examples in the literature compare putatively neutral (FST) and quantitative genetic (QST) differentiation in multiple populations to assess their evolutionary signature and identify candidate traits involved with local adaptation. Investigating these signatures in closely related or recently diversified species has the potential to shed light on the divergence processes acting at the interspecific level. Here, we conducted this comparison in two subspecies of snapdragon plants (eight populations of Antirrhinum majus pseudomajus and five populations of A. m. striatum) in a common garden experiment. We also tested whether altitude was involved with population phenotypic divergence. Our results identified candidate phenological and morphological traits involved with local adaptation. Most of these traits were identified in one subspecies but not the other. Phenotypic divergence increased with altitude for a few biomass‐related traits, but only in A. m. striatum. These traits therefore potentially reflect A. m. striatum adaptation to altitude. Our findings imply that adaptive processes potentially differ at the scale of A. majus subspecies. 相似文献
18.
Wilson AJ Morrissey MB Adams MJ Walling CA Guinness FE Pemberton JM Clutton-Brock TH Kruuk LE 《Journal of evolutionary biology》2011,24(4):772-783
By determining access to limited resources, social dominance is often an important determinant of fitness. Thus, if heritable, standard theory predicts mean dominance should evolve. However, dominance is usually inferred from the tendency to win contests, and given one winner and one loser in any dyadic contest, the mean proportion won will always equal 0.5. Here, we argue that the apparent conflict between quantitative genetic theory and common sense is resolved by recognition of indirect genetic effects (IGEs). We estimate selection on, and genetic (co)variance structures for, social dominance, in a wild population of red deer Cervus elaphus, on the Scottish island of Rum. While dominance is heritable and positively correlated with lifetime fitness, contest outcomes depend as much on the genes carried by an opponent as on the genotype of a focal individual. We show how this dependency imposes an absolute evolutionary constraint on the phenotypic mean, thus reconciling theoretical predictions with common sense. More generally, we argue that IGEs likely provide a widespread but poorly recognized source of evolutionary constraint for traits influenced by competition. 相似文献
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Chromosomal inversions can play an important role in adaptation, but the mechanism of their action in many natural populations remains unclear. An inversion could suppress recombination between locally beneficial alleles, thereby preventing maladaptive reshuffling with less‐fit, migrant alleles. The recombination suppression hypothesis has gained much theoretical support but empirical tests are lacking. Here, we evaluated the evolutionary history and phenotypic effects of a chromosomal inversion which differentiates annual and perennial forms of Mimulus guttatus. We found that perennials likely possess the derived orientation of the inversion. In addition, this perennial orientation occurs in a second perennial species, M. decorus, where it is strongly associated with life history differences between co‐occurring M. decorus and annual M. guttatus. One prediction of the recombination suppression hypothesis is that loci contributing to local adaptation will predate the inversion. To test whether the loci influencing perenniality pre‐date this inversion, we mapped QTLs for life history traits that differ between annual M. guttatus and a more distantly related, collinear perennial species, M. tilingii. Consistent with the recombination suppression hypothesis, we found that this region is associated with life history in the absence of the inversion, and this association can be broken into at least two QTLs. However, the absolute phenotypic effect of the LG8 inversion region on life history is weaker in M. tilingii than in perennials which possess the inversion. Thus, while we find support for the recombination suppression hypothesis, the contribution of this inversion to life history divergence in this group is likely complex. 相似文献