Sex-biased gene flow in spectacled eiders (Anatidae): inferences from molecular markers with contrasting modes of inheritance.
ABSTRACT Genetic markers that differ in mode of inheritance and rate of evolution (a sex-linked Z-specific microsatellite locus, five biparentally inherited microsatellite loci, and maternally inherited mitochondrial [mtDNA] sequences) were used to evaluate the degree of spatial genetic structuring at macro- and microgeographic scales, among breeding regions and local nesting populations within each region, respectively, for a migratory sea duck species, the spectacled eider (Somateria fisheri). Disjunct and declining breeding populations coupled with sex-specific differences in seasonal migratory patterns and life history provide a series of hypotheses regarding rates and directionality of gene flow among breeding populations from the Indigirka River Delta, Russia, and the North Slope and Yukon-Kuskokwim Delta, Alaska. The degree of differentiation in mtDNA haplotype frequency among breeding regions and populations within regions was high (phiCT = 0.189, P < 0.01; phiSC = 0.059, P < 0.01, respectively). Eleven of 17 mtDNA haplotypes were restricted to a single breeding region. Genetic differences among regions were considerably lower for nuclear DNA loci (sex-linked: phiST = 0.001, P > 0.05; biparentally inherited microsatellites: mean theta = 0.001, P > 0.05) than was observed for mtDNA. Using models explicitly designed for uniparental and biparentally inherited genes, estimates of spatial divergence based on nuclear and mtDNA data together with elements of the species' breeding ecology were used to estimate effective population size and degree of male and female gene flow. Differences in the magnitude and spatial patterns of gene correlations for maternally inherited and nuclear genes revealed that females exhibit greater natal philopatry than do males. Estimates of generational female and male rates of gene flow among breeding regions differed markedly (3.67 x 10(-4) and 1.28 x 10(-2), respectively). Effective population size for mtDNA was estimated to be at least three times lower than that for biparental genes (30,671 and 101,528, respectively). Large disparities in population sizes among breeding areas greatly reduces the proportion of total genetic variance captured by dispersal, which may accelerate rates of inbreeding (i.e., promote higher coancestries) within populations due to nonrandom pairing of males with females from the same breeding population.
SourceAvailable from: Jennifer Ann Moore[Show abstract] [Hide abstract]
ABSTRACT: Predictive relationships between estimates of functional population connectivity and physical and biotic landscape features can provide important insights into present and future population responses to human-mediated landscape change. Quantification of associations between landscape features and dispersal or genetic surrogates such as gene flow among areas can be particularly challenging for continuously distributed and highly mobile wildlife species. We assessed the relative influence of natural and human-altered landscape features on white-tailed deer (Odocoileus virginianus) spatial genetic structure (SGS) in southern Michigan (USA) using 7 microsatellite markers assayed for 326 adult individuals from 21 contiguous counties (33,284 km2). We used previously collected telemetry data to quantify probabilities of habitat occupancy and seasonal movements that allowed selection and weighting of landscape features to create habitat suitability indices (HSI). We assigned individuals to groups (n = 13) for statistical analyses quantifying relationships between measures of SGS (response variable) with Euclidean distance, least cost distances parameterized using HSI, and presence of natural (rivers) and man-made (roads) barriers to dispersal. Over the entire study area, genetic differentiation was significant (mean Fst = 0.019, P < 0.001) and increased with increasing inter-group geographic distance (r2 = 0.381; P < 0.05). We identified features in the landscape matrix between groups including rivers, high traffic roads, and habitats of intermediate HSI as inhibiting gene flow. Low HSI was associated with low between-group Fst and appeared to facilitate gene flow. Quantification of the relative importance of man-made barriers (roads) and habitat suitability to SGS for white-tailed deer emphasizes the importance of joint use of ecological and genetic analyses in conservation and control efforts for abundant and mobile wildlife species. © 2014 The Wildlife Society.Journal of Wildlife Management 12/2014; 79(2). DOI:10.1002/jwmg.826 · 1.61 Impact Factor
Technical Report: Spatiotemporal distribution and migratory patterns of Spectacled Eiders