Warbler genomes look to be 99.97 percent alike

Date: August 23, 2016

Source: Cornell University

For decades, conservationists have considered blue-winged warblers to be a threat to golden-winged warblers, a species being considered for federal Endangered Species protection. Blue-winged warbler populations have declined 66 percent since 1968, according to the North American Breeding Bird Survey.

The two species are known to frequently interbreed where they co-occur, and scientists have been concerned that the more numerous blue-winged warblers would genetically swamp the rarer golden-wing gene pool.

New research from the Cornell Lab of Ornithology's Fuller Evolutionary Biology Program shows that, genetically speaking, blue-winged and golden-winged warblers are almost identical. Scientists behind the research say the main differences between the two species are in feather color and pattern, in some cases just a simple matter of dominant or recessive pairings of gene variants, or alleles.

"We think we have finally pinpointed the proverbial genomic 'needle in the haystack' between these taxa," said study co-author David Toews, adding the findings suggest conservationists should be less concerned with hybridization and primarily focused on preserving habitat for both species. "This is something that conservation practitioners have wanted for a very long time."

The research is published in the September issue of the journal Current Biology. Toews' collaborators include fellow Cornell Lab postdoctoral researcher Scott Taylor, along with partners from Cornell University's Department of Biological Statistics and Computational Biology, the University of California at Riverside and Environment and Climate Change Canada.

The team investigated the genetic architecture behind the differences between the two warblers by analyzing the genomes of 10 golden-winged and 10 blue-winged warblers from New York, with birds sampled from the Sterling Forest along the New Jersey border to the St. Lawrence River Valley. Across their analysis of the entire genomes of both species, they found only six regions (or less than .03 percent) that showed strong differences. In other words, blue-winged and golden-winged warblers are 99.97 percent alike genetically.

Continued