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