Genomic variation in the black-throated green warbler (Setophaga virens) suggests divergence in a disjunct Atlantic Coastal Plain population (S. v. waynei)
Running title: Divergence in the Black-throated Green Warbler
John P. Carpenter1*, Alexander J. Worm1,2, Than J. Boves2, Andrew W. Wood3, Joseph P. Poston4, David P.L. Toews3*
1Wildlife Diversity Program, North Carolina Wildlife Resources Commission, Raleigh, NC 27699, USA
2Department of Biological Sciences, Arkansas State University, Jonesboro, Arkansas 72401, USA
3Department of Biology, Penn State University, University Park, PA 16802, USA
4Department of Biology, Catawba College, Salisbury, NC 28144, USA
*Corresponding authors
John P. Carpenter:john.carpenter@ncwildlife.org
David P.L. Toews: toews@psu.edu
Abstract (about 250 words)
New World wood warblers (family: Parulidae) can exhibit strong phenotypic differences among species, particularly in song and plumage. However, within-species variation in these warblers—often designated as subspecies—is much more subtle and has led to significant debate over the origin, maintenance, and conservation status of populations that differ. A species that exhibits controversial subspecific status is the black-throated green warbler (Setophaga virens ), a Neotropical-Nearctic migrant that breeds throughout eastern and boreal North America with several isolated populations at the margins of its range. In particular, uncertainty has lingered over the status ofS. v. waynei , a disjunct population along the southeast Atlantic Coastal Plain of the United States that differs morphologically and ecologically from the nominate subspecies. Despite its unique circumstances, the subspecific status of S. v. wayne i remains questionable in the absence of any population-wide genomic analyses. Here, we employ whole-genome resequencing to estimate the genetic distinctiveness among samples collected across the entirety of S. virens breeding range, including from putative S. v. waynei . Despite detecting low global differentiation (FST = 0.027) across the entire species, we observed discrete genetic clustering among S. v. waynei . Principal components analysis of genome-wide differences shows the main axis of variation separatesS. v. waynei from all other S. v. virens samples. We also found that S. v. waynei is most similar to another isolated population from the Piedmont of North Carolina and detected evidence of a historical north-to-south geographic dispersal among the entire complex. Combined with previously documented ecological and morphological distinctness, our results support that S. v. wayneibe considered a distinct and recognized subspecies worthy of targeted conservation efforts.
KEYWORDS
Setophaga virens waynei , whole-genome resequencing, principal component analysis, phylogeny, next-generation sequencing, population genomics, Parulidae