“A migratory divide in the Painted Bunting (Passerina ciris)”

Posted on

C. J. Battey, Ethan B. Linck, Kevin L. Epperly, Cooper French, David L. Slager, Paul W. Sykes Jr., and John Klicka (Feb 2018)

The DOI is http://dx.doi.org/10.1086/695439

Genomic data maps migration in a songbird and confirms a 66-yr-old hypothesis of trans-gulf migration

Painted Bunting (Passerina ciris).
(Illustration by Kevin Epperly)

Every spring, temperate North America welcomes the arrival of one of the continent’s most striking songbirds, the Painted Bunting, to their breeding grounds in northern Mexico and the Southeastern US. What we haven’t known, until recently, is exactly where they’re coming from. Now researchers at the University of Washington and Burke Museum of Natural History have used genetic data to map the annual migration of the species, and discovered an unexpected difference in the flight paths of populations in Texas and Louisiana. The team, working in the lab of Burke Museum Curator of Ornithology John Klicka, sequenced DNA and took measurements of the size and shape of Painted Buntings caught both while breeding and while overwintering. With these data, they used mathematical models to identify groups of individuals that share a recent common ancestor, drawing links between different parts of the species’ two seasonal ranges. The researchers found that breeding birds in Louisiana are closely related to wintering birds from the Yucatán Peninsula; meanwhile, breeding populations in Texas, Kansas, and Oklahoma match wintering samples from western and central Mexico. Breeding birds from the Atlantic Coast, meanwhile, appear to winter only in Florida, the Bahamas, and Cuba, and rarely interbreed with other populations. The data provides the first evidence that Painted Buntings using different migratory routes are also genetically differentiated, thus shedding light on how seasonal migration shapes the evolution of songbirds. Additionally, they show that declining populations along the Atlantic Coast and in the Mississippi River Valley are unique in both their genes and their life history, and should be treated as independent units by conservationists looking to preserve this iconic species.


Abstract

In the Painted Bunting (Passerina ciris), a North American songbird, populations on the Atlantic coast and interior southern United States are known to be allopatric during the breeding season, but efforts to map connectivity with wintering ranges have been largely inconclusive. Using genomic and morphological data from museum specimens and banded birds, we found evidence of three genetically differentiated Painted Bunting populations with distinct wintering ranges and molt-migration phenologies. In addition to confirming that the Atlantic coast population remains allopatric throughout the annual cycle, we identified an unexpected migratory divide within the interior breeding range. Populations breeding in Louisiana winter on the Yucatán Peninsula, and are parapatric with other interior populations that winter in mainland Mexico and Central America. Across the interior breeding range, genetic ancestry is also associated with variation in wing length, suggesting that selection may be promoting morphological divergence in populations with different migration strategies.

Read the Article