Consistent gemomic signatures of reproductive isolation in a moving avian hybrid zone

TAYLOR, SCOTT A.; CURRY, ROBERT L.; FERRETTI VALENTINA; LOVETTE, IRBY J.

Estes Park

Congreso; American Ornithologists' Union, Cooper Ornithological Society and Society for Canadian Ornithologists joint meeting; 2014

American Ornithologists' Union, Cooper Ornithological Society and Society for Canadian Ornithologists

Studies of hybrid zone dynamics often investigate a single sampling period and draw conclusions from that temporal snapshot, but stochasticity can result in loci with patterns that differ from neutral expectations. Comparing admixed populations from different geographic regions is one way to detect consistently divergent regions potentially involved in reproductive isolation. Temporal comparisons address the same problem, but have not been investigated. In North America, black-capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadees hybridize in a contact zone extending from New Jersey to Kansas. The hybrid zone is likely maintained by strong intrinsic selection against hybrids, and it is moving north in response to climate change. We used a reduced representation genomic approach and temporally spaced sampling?two samples of ~80 individuals separated by a decade? to determine the pattern and consistency of selection and introgression in the chickadee hybrid zone. We report consistently low introgression for highly divergent loci between P. atricapillus and P. carolinensis in this moving hybrid zone. This is strong evidence that these loci are linked to genomic regions involved in reproductive isolation between chickadees. This spatiotemporal genomic analysis highlights the benefits of examining hybrid zones at multiple time points, and in different geographic contexts, when investigating reproductive isolation between closely relatedspecies.