How far is too close? restricted, sex‐biased dispersal in black‐capped vireos

Abstract

Understanding the interplay of dispersal and how it translates into gene flow is key to understanding population processes, and especially so for endangered species occupying fragmented habitats. In migratory songbirds, there is evidence that long-distance movement capabilities do not translate well into observed dispersal. Our objectives were to (i) define the fine-scale spatial genetic structure in endangered black-capped vireos to characterize dispersal patterns and (ii) to correlate dispersal dynamics to overall population genetic structure using a simulation approach. We sampled 160 individuals over 2 years to (i) describe the fine-scale genetic structuring and (ii) used this information to model scenarios to compare with actual data on change in population structuring over a 100-year interval. We found that black-capped vireos exhibit male philopatry and restricted dispersal distances, relative to females. Our simulations also support a sex-biased dispersal model. Additionally, we find that fragmentation related changes in rates of dispersal might be a likely cause for increasing levels of population structure over a 100-year period. We show that restricted sex-biased dispersal can explain population structuring in this species and that changes in dispersal rates due to fragmentation may be a continuing threat to genetic viability in this species.

Similarity in temporal variation in sex‐biased dispersal over short and long distances in the dark‐eyed junco,Junco hyemalis

“…We note that the number of loci is less important for power of genetic spatial autocorrelation analyses than number of samples, and when sample sizes are large, Type I and Type II error rates are small (Athrey et al . ; Banks & Peakall ). While our number of samples per year (Table ) would have been adequate, though not exceptionally large, the Multiple Population Subsets analyses we used combined multiple years in each analysis, resulting in large sample sizes ( birds) and, theoretically, low error rates.…”

“…Gf05 also had a very high error rate in scoring resulting in an 11.7% mother-offspring mismatch rate (Supplementary Materials: Gerlach et al 2012), so was likewise excluded. We note that the number of loci is less important for power of genetic spatial autocorrelation analyses than number of samples, and when sample sizes are large, Type I and Type II error rates are small (Athrey et al 2012;Banks & Peakall 2012…”

“…; Athrey et al . ). Yet, there is new evidence from mark–recapture studies that sex biases in dispersal are not evolutionarily fixed but can vary in ecological time, both in terms of which sex disperses (Perez‐Gonzalez & Carranza ; Eikenaar et al .…”

“…These phylogenetically distinct patterns found in mammals and birds have led to the generalization that patterns of sex bias in dispersal have evolved in a common ancestor of each taxon (Pusey 1987;Lawson Handley & Perrin 2007). This presumption of an evolutionary basis for sex biases in dispersal that are consistent within species has influenced how molecular indices of dispersal are analysed, and it is common for studies to combine molecular data from multiple years to increase sample size and detection power (Beck et al 2008;Dubey et al 2008;Blackmore et al 2011;Liebgold et al 2011;Athrey et al 2012). Yet, there is new evidence from mark-recapture studies that sex biases in dispersal are not evolutionarily fixed but can vary in ecological time, both in terms of which sex disperses (Perez-Gonzalez & Carranza 2009;Eikenaar et al 2010;Richardson et al 2010), as well as the likelihood or distance of that dispersal (Eikenaar et al 2010;P erez-Espona et al 2010).…”

Fluctuating fire regimes and their historical effects on genetic variation in an endangered shrubland specialist

“…2008; Athrey et al. 2012a,b), there are not multiple evolutionarily significant units within BCVI despite existing as a single distinct lineage for over 1 million ybp. The geographic area occupied as at least the LIG is likely too small for isolating barriers to cause significant historical structuring.…”