Consistent genomic signatures of reproductive isolation in a hybrid zone responding to climate change

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

Raleigh

Congreso; Evolution meeting 2014; 2014

Studies of hybrid zone dynamics often investigate a single samplingperiod and draw conclusions from that temporal snapshot, butstochasticity can result in loci with patterns that differ from neutralexpectations. Comparing admixed populations from differentgeographic regions is one way to detect consistently divergentregions potentially involved in reproductive isolation. Temporalcomparisons address the same problem, but have not beeninvestigated. In North America, black-capped (Poecile atricapillus)and Carolina (P. carolinensis) chickadees hybridize in a contactzone extending from New Jersey to Kansas. The hybrid zone islikely maintained by strong intrinsic selection against hybrids, and itis moving north in response to climate change. We used a reducedrepresentation genomic approach and temporally spacedsampling?two samples of ~80 individuals separated by a decade?to determine the pattern and consistency of selection andintrogression in the chickadee hybrid zone. We report consistently low introgression for highly divergent loci between P. atricapillusand P. carolinensis in this moving hybrid zone. This is strongevidence that these loci are linked to genomic regions involved inreproductive isolation between chickadees. This spatiotemporalgenomic analysis highlights the benefits of examining hybrid zonesat multiple time points, and in different geographic contexts, wheninvestigating reproductive isolation between closely relatedspecies.