Low but contrasting neutral genetic differentiation shaped by winter temperature in European great tits (original) (raw)
Related papers
Dispersal, Gene Flow, and Population Structure
The Quarterly Review of Biology, 1999
The accuracy ofgenejlozo estinzates is unknown in most natural popzllations becazise direct estimates of dispersal are often not possible. These estimates can be highly imprecise or men biased becazlsepopulation genetic structzlre rejlects more than a simple balance between genetic drft and gene Pow. Most of the models used to estimate gene flow also asszln7e very simple patterns o j movement. As a result, mu1tii)le interpretations of population structure involving contemporary genejlozu, departzlresfrom equilibrium, and otherfactors are almost alwajs possible. One waj to isolate the relative contribution of gene j7ow to lopulation genetic differentiation is to utilize comparative methods. Popzilation genetic statistics szich as F,,, heterozygosity and Areii D can be comfiared between species with d~fmingdis~ersal abilities ifthese species are otizemisephylogeneti-ca10, geopaphicallq' and demopaphicallq' comparable. Accordingb, the available literatzire was searched for all grozips that meet these criteria to determine whether liroad conclzisions regarding the relationships between dispersal, popz~lation genetic structure, and gene flow estimates are posrible. Allozjme and mtDNA data were szimmarizedfor 27 animal grozips i n which dispersal differences can be characterized. I n total, genetic data were obtained for 333 species of vertehrcites and inverlehrates from terrestrial, freshwater and marine habitats. Across these groups, dispersal ability was consistenth related to population structure, with a mean ranlt correlation o f-0.72 between ranlted dispersal ability and F\i. Gene flow estimates derived from private alleles were also cor~elated with dispersal ability, but were less zuideh available. Direct-cozint Izeterozygositj and average values ofNei i D showed moderate de,yrees of correlation with disfiersal ability. Thus, .-despite regzonal, taxonomic and methodological dz3fmnces among tizepoups ofspecies szlr-uejed, available data demonstrate that dispersal makes a measurable contribzition to population qenetic .-A dqferentiation i n the majority of animal species i n natzire, and that genej7ow estimates are rare0 so overwhelmed by population histoq, depaitures from eqziilibjium, or other nzicroevolzitio~zary forces as to be uninformative. A CENTFLU challenge for organismal differ genetically (hereafter referred to as the biologists is to establish links between the level of population genetic differentiation). ecology and the evolution of species. One This is because an in-depth understanding of such link is provided by quantifying the rela-microevolution requires a quantification of tionship between dispersal ability and the mag-how the movement of genes among populanitude and spatial scale over which populations tions (i.e., gene flow) interacts with genetic
Drift and Gene Flow in Shaping Spatial Patterns of Genetic Differentiation
2015
Spatial patterns of neutral genetic diversity are often investigated to infer gene flow in wild populations. However, teasing apart the influence of gene flow from the effect of genetic drift is challenging given that both forces are acting simultaneously on patterns of genetic differentiation. Here, we tested the relevance of a distance-based metric-based on estimates of effective population sizes or on environmental proxies for local carrying capacities-to assess the unique contribution of genetic drift on pairwise measures of genetic differentiation. Using simulations under various models of population genetics, we demonstrated that one of three metrics we tested was particularly promising: it correctly and uniquely captured variance in genetic differentiation that was due to genetic drift when this process was modelled. We further showed that (i) the unique contribution of genetic drift on genetic differentiation was high (up to 20 %) even when gene flow was high and for relatively high effective population sizes, and (ii) that this metric was robust to uncertainty in the estimation of local effective population size (or proxies for carrying capacity). Finally, using an empirical dataset on a freshwater fish (Gobio occitaniae), we demonstrated the usefulness of this metric to quantify the relative contribution of genetic drift and gene flow in explaining pattern of genetic differentiation in this species. We conclude that considering Isolation-by-Drift metrics will substantially improve the understanding of evolutionary drivers of observed spatial patterns of genetic variation.
Biome and migratory behaviour significantly influence vertebrate genetic diversity
Biological Journal of the Linnean Society, 2017
Genetic diversity (GD) is largely determined by effective population size, which may vary dramatically for species that differ in key aspects of their biology such as vagility. To identify evolutionary patterns associated with animal distributions and movements, we examined relationships among GD (i.e. microsatellite heterozygosity and allelic richness), taxonomic class, biome and migratory behaviour. Linear regression revealed that migratory mammals, reptiles, amphibians and fishes had less GD compared to nonmigratory species, whereas migratory birds had more GD than their nonmigratory counterparts. We also found that the biome a species inhabits influences the GD of migratory and nonmigratory species differently. For example, migratory amphibians at low latitudes are more genetically diverse than migratory amphibians at higher latitudes. However, we found the reverse relationship (i.e. decreased GD in low-latitude migratory species compared to higher latitude migratory species) in mammals and fishes and no influence of biome on reptile GD. We suggest that these differences are a result of differences in vagility, the extent of philopatry among the classes and perhaps differential selection between terrestrial and aquatic species. We argue that these categorical disparities in GD reflect changes in effective population size driven at least partly by differences in habitat.
Scientific Reports, 2020
Understanding the population genetic consequences of habitat heterogeneity requires assessing whether patterns of gene flow correspond to landscape configuration. Studies of the genetic structure of populations are still scarce for neotropical forest birds. We assessed range-wide genetic structure and contemporary gene flow in the thorn-tailed rayadito (Aphrastura spinicauda), a passerine bird inhabiting the temperate forests of South America. We used 12 microsatellite loci to genotype 582 individuals from eight localities across a large latitudinal range (30°S-56°S). Using population structure metrics, multivariate analyses, clustering algorithms, and Bayesian methods, we found evidence for moderately low regional genetic structure and reduced gene flow towards the range margins. Genetic differentiation increased with geographic distance, particularly in the southern part of the species' distribution where forests are continuously distributed. populations in the north seem to experience limited gene flow likely due to forest discontinuity, and may comprise a demographically independent unit. The southernmost population, on the other hand, is genetically depauperate and different from all other populations. Different analytical approaches support the presence of three to five genetic clusters. We hypothesize that the genetic structure of the species follows a hierarchical clustered pattern. Investigating how genetic variation is distributed across a species' geographic range is fundamental to identify the factors contributing to demographic and population structure 1. Studies of range-wide genetic structure not only provide information about dispersal rates and population connectivity, but also allow a better understanding of how contemporary population dynamics are linked to spatial and temporal environmental variation 2. In species with restricted dispersal, genetic variation is often found to vary continuously across space, such that genetic differentiation increases with geographic distance-isolation by distance (IBD) 3-5. However, distinct landscape features can act as barriers to dispersal and may have a profound impact on gene flow and population dynamicsisolation by resistance (IBR) 6. As limited dispersal and physical and environmental barriers promote the isolation of local populations, they can ultimately lead to genetic differentiation and divergence or to local extinctions 7,8 .
Extremely reduced dispersal and gene flow in an island bird
Heredity, 2014
The Ré union grey white-eye, Zosterops borbonicus, a passerine bird endemic to Ré union Island in the Mascarene archipelago, represents an extreme case of microgeographical plumage colour variation in birds, with four distinct colour forms occupying different parts of this small island (2512 km 2). To understand whether such population differentiation may reflect low levels of dispersal and gene flow at a very small spatial scale, we examined population structure and gene flow by analysing variation at 11 microsatellite loci among four geographically close localities (o26 km apart) sampled within the distribution range of one of the colour forms, the brown-headed brown form. Our results revealed levels of genetic differentiation that are exceptionally high for birds at such a small spatial scale. This strong population structure appears to reflect low levels of historical and contemporary gene flow among populations, unless very close geographically (o10 km). Thus, we suggest that the Ré union grey white-eye may shows an extremely reduced propensity to disperse, which is likely to be related to behavioural processes.
A novel migratory polymorphism evolved within the last 60 years in blackcaps (Sylvia atricapilla) breeding sympatrically in southwestern Germany. While most individuals winter in the traditional areas in the Mediterranean, a growing number of blackcaps started migrating to Britain instead. The rapid microevolution of this new strategy has been attributed to assortative mating and better physical condition of birds wintering in Britain. However, the isolating barriers as well as the physical condition of birds are not well known. In our study, we examined whether spatial isolation occurred among individuals with distinct migratory behaviour and birds with different arrival dates also differed in physical and genetic condition. We caught blackcaps in six consecutive years upon arrival on the breeding grounds and assigned them via stable isotope analysis to their wintering areas. Analysis of the vegetation structure within blackcap territories revealed different microhabitat preferences of birds migrating to distinct wintering areas. Blackcaps arriving early on the breeding grounds had higher survival rates, better body condition and higher multilocus heterozygosities than later arriving birds. We did however not find an effect of parasite infection status on arrival time. Our results suggest that early arriving birds have disproportionate effects on population dynamics. Allochrony and habitat isolation may thus act together to facilitate ongoing divergence in hybrid zones, and migratory divides in particular.
The multifarious effects of dispersal and gene flow on contemporary adaptation
Functional Ecology, 2007
Dispersal and gene flow can have a variety of interacting effects on evolution. These effects can either promote or constrain adaptive divergence through either genetic or demographic routes. The relative importance of these effects is unknown because few attempts have been made to conceptually integrate and test them. 2. We draw a broad distinction between situations with vs. without strong coevolutionary dynamics. This distinction is important because the adaptive peak for a given population is more mobile in the former than in the latter. This difference makes ongoing evolutionary potential more important in the presence of strong coevolutionary dynamics than in their absence. 3. We advance a conceptual integration of the various effects of gene flow and dispersal on adaptive divergence. In line with other authors, but not necessarily for the same reasons, we suggest that an intermediate level of gene flow will allow the greatest adaptive divergence. 4. When dispersal is quite low, we predict that an increase will have positive effects on adaptive divergence, owing to genetic/demographic rescue and 'reinforcement.' The rescue effect may be more important in small populations and in homogeneous environments. The reinforcement effect may be more common in large populations and in heterogeneous environments. 5. Once a certain level of dispersal is reached, we predict that a further increase may have negative effects on adaptive divergence. These effects may arise if carrying capacity is exceeded or maladaptive genes are introduced. 6. Many additional effects remain to be integrated into this framework, and doing so may yield novel insights into the factors influencing evolution on ecological time-scales.