Evolutionarily labile dispersal behavior and discontinuous habitats enhance population differentiation in island vs continentally distributed swallows

The causes of population divergence in vagile groups remain a paradox in evolutionary biology: dispersive species should be able to colonize new areas, a prerequisite for allopatric speciation, but dispersal also facilitates gene flow, which erodes population differentiation. Strong dispersal ability has been suggested to enhance divergence in patchy habitats and inhibit divergence in continuous landscapes, but empirical support for this hypothesis is lacking. Here we compared patterns of population divergence in a dispersive clade of swallows distributed across both patchy and continuous habitats. The Pacific Swallow (Hirundo tahitica) has an insular distribution throughout Southeast Asia and the Pacific, while its sister species, the Welcome Swallow (H. neoxena), has a continental distribution in Australia. We used whole-genome data to demonstrate strong genetic structure and limited introgression among insular populations, but not among continental populations. Demographic models sho..., , , # Data from: Evolutionarily labile dispersal behavior and discontinuous habitats enhance population differentiation in island vs. continentally distributed swallows

[https://doi.org/10.5061/dryad.18931zd3m](https://doi.org/10.5061/dryad.18931zd3m)

## Description of the data and file structure

Included is a .vcf file of all samples used in the analysis filtered to have minimum depth of 5, maximum depth of 50, minimum read quality of 30, minor allele frequency of 5%, and less than 15% missing data. Outgroup samples are included. Metadata are available in Table S1 of the manuscript.

The water_gaps.csv file includes the geographic distances and water gap classifications used in analyses of isolation by distance.

* The first column indicates the minimum as the crow flies distance between populations in km.
* The second column indicates the distance between the center of two populations in km; this is relevant only for welcome swallows, where dispersed samples from across different regio...