DOI: 10.5061/dryad.18931zd3m
title: Data from: Evolutionarily labile dispersal behavior and discontinuous habitats enhance population differentiation in island vs continentally distributed swallows

description: 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 show that historic changes in habitat connectivity have contributed
 to population structure within the clade. Swallows appear to exhibit
 evolutionarily labile dispersal behavior in which they reduce dispersal
 propensity after island colonization despite retaining strong flight
 ability. Our data support the hypothesis that fragmented habitats enhance
 population differentiation in vagile groups, and suggest that labile
 dispersal behavior is a key mechanism underlying this pattern.
description: # 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 regions of Australia were grouped into "populations". * The third column gives the maximum water gap distance between populations in km. The NA's are for continental populations that are not separated by water gaps. * The fourth column gives pairwise FST between populations. * The fifth column indicates the water gap type, with cont = continental (i.e. no water gap), large = water gap &gt; 600km, and small = water gap &lt; 600km. The fifth column indicates which species/populations were compared in the contrast, among Pacific, Welcome, Hill, and Tahiti swallows. For example, "pac" indicates two Pacific swallow populations were compared and "pac_hill" indicates Pacific and Hill swallows were compared. * The sixth column indicates whether the contrast is intra- or interspecific, with e.g. "pac" meaning an intraspecific pacific swallow comparison and "int_sp" indicating an interspecific comparison. * The last column indicates the geographic regions used to measure the maximum water gap distance. For the continental populations, the last column gives which specific populations were compared.