Riparian areas potentially provide crucial corridors through fragmented landscape for black-capped vireo (Vireo atricapilla) source-sink system

Abstract

Dispersal is a foundational ecological and evolutionary process that facilitates population connectivity and resiliency and yet is vastly understudied. With landscape genetics, we can elucidate how environmental features and patch characteristics influence gene flow and therefore dispersal. Our main objective was to investigate how landscape features influence gene flow in the black-capped vireo source-sink system in central Texas. We genotyped 338 black-capped vireos at 12 microsatellite loci from 6 differentiated populations to test the relationships of Euclidean distance, elevation, and land cover types (water, development, forest, scrub, open, agriculture and riparian) with gene flow. We also tested how at-site variables, brown-headed cowbird control and area of scrub habitat, affected gene flow in our models. We found that riparian and agricultural areas facilitate gene flow while development and open habitat impede gene flow. Agriculture as a potential corridor was an unexpected finding in need of further study but indicates an exciting new avenue for black-capped vireo dispersal research. In combination with findings from Dittmar et al. (2014), we inferred that riparian areas may be important corridors for black-capped vireo dispersal during post-fledgling movements, particularly in fragmented landscapes. Therefore, protecting riparian areas may help mitigate the isolating effects of habitat fragmentation and would be an important conservation effort as habitat fragmentation continues in the future.