HOW STABLE ARE HYBRID ZONES IN THE FACE OF CLIMATE CHANGE?
|Daniel K Pierce; University of California Riverside; email@example.com; Alan Brelsford
Hybrid zone stability depends on a balance between dispersal into the hybrid zone and selection against hybrids. Environmental change can influence dispersal and selection and lead to displacement of a hybrid zone, so a moving hybrid zone may indicate ecologically and evolutionarily important environmental change. We examine a historically stable hybrid zone between Audubon’s and myrtle yellow-rumped warblers to determine if a recent Mountain Pine Beetle outbreak has had an effect on the location of this hybrid zone. The mountain pine beetle outbreak west of the Canadian Rocky Mountains has led to the degradation of much of the yellow-rumped warbler breeding habitat, primarily in the region occupied by Audubon’s warblers. Using geographic clines in genetic data from over a thousand yellow-rumped warblers sampled across 16 years, we estimate the historical and contemporary positions of the hybrid zone. By comparing the location of the hybrid zone between time periods at four transects that differ in severity of the mountain pine beetle outbreak, we assess this hybrid zone's stability and discuss the potential for climate change to influence species boundaries.