Abstract
Dispersal affects both social behavior and population structure and is therefore a key determinant of long-term population persistence. However, dispersal strategies and responses to spatial habitat alteration may differ between sexes. Here we analyzed spatial and temporal variation in ten polymorphic microsatellite DNA loci of male and female Cabanis’s greenbuls ( Phyllastrephus cabanisi ), a cooperative breeder of Afrotropical rainforest, to quantify rates of gene flow and fine-grained genetic structuring within and among fragmented populations. We found genetic evidence for female-biased dispersal at small spatial scales, but not at the landscape level. Local autocorrelation analysis provided evidence of positive genetic structure within 300 m distance ranges, which is consistent with behavioral observations of short-distance natal dispersal. At a landscape scale, individual-based autocorrelation values decreased over time while levels of admixture increased, possibly indicating increased gene flow over the past decade.
Highlights
Dispersal plays a major role in contemporary dynamics and the evolutionary potential of a population [1]
Population structure We identified two genetic clusters (K=2) in period 1 (ΔK=183), whereby population CH was separated from all other populations (Table 1, Figure 3)
Genetic connectivity increased over time, but there was no unequivocal evidence that this was due to a disproportional increase in gene flow by the most dispersive sex
Summary
Dispersal plays a major role in contemporary dynamics and the evolutionary potential of a population [1]. Empirical evidence has accumulated that species exhibiting asymmetrical dispersal behavior, i.e., when one sex is more dispersive than the other, are even more prone to having distorted population dynamics in response to environmental variation [9,10,11,12,13]. According to the resource hypothesis [14], female-biased dispersal predominates in birds as male birds are the most active sex in both resource and territory defense and benefit more from being familiar with their natal surrounding [14,15]. Between-fragment dispersal may be heavily influenced by the intervening matrix in such a way that selective forces are invariant with respect to both sexes, balancing dispersal rates in females and males at a regional scale [17]. The availability and decreasing cost of polymorphic genetic markers has made it possible to indirectly infer the prevalence and extent of such patterns, as asymmetric dispersal typically results in higher genetic similarity between neighbors and more genetic structure in the philopatric sex [18,19,20]
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