Analysis of multilocus DNA reveals hybridization in a contact zone between Empidonax flycatchers

Contact zones between recently diverged taxa offer unique opportunities to test whether the forms are reproductively isolated and therefore distinct species. The Pacific-slope flycatcher Empidonax difficilis and Cordilleran flycatcher Empidonax occidentalis are closely related taxa that were officially separated into two species in 1989, a treatment that… CONTINUE READING