Data from: Habitat fragmentation in coastal southern California disrupts genetic connectivity in the Cactus Wren (Campylorhynchus brunneicapillus)

Characterizing genetic connectivity patterns can be beneficial for managing populations of low vagility species by providing insight on gene flow and the effects of habitat fragmentation. Urbanization over the past half century in coastal southern California has caused both precipitous coastal sage scrub habitat loss and declines in populations of the cactus wren (Campylorhynchus brunneicapillus). Using 22 microsatellite loci, we found that remnant cactus wren aggregations in coastal southern California comprised 20 populations based upon strict exact tests and 12 genetic clusters with hierarchical Bayesian clustering analyses. Isolation by distance patterns varied over the study area, which we attribute to temporal differences in anthropogenic landscape development. Genetic structure patterns largely mirrored underlying land-use, with cluster and population boundaries coinciding with habitat gaps created primarily by urbanization. Using a habitat model we developed, we detected a stronger associations between ecological and genetic distances than geographic distances. Within populations, we developed, we detected a positive association between available local habitat and allelic richness and a negative association with relatedness within populations. We also found that genetic bottleneck signals were associated with wildfire frequency. These results indicate that habitat fragmentation and alterations have reduced genetic connectivity and diversity of cactus wren populations in coastal southern California. Management efforts focused on improving connectivity among remaining populations may help to ensure population persistence.