Genetic Sample Preparation
Our final dataset (n = 29) included five S. v. virenssamples from New York that were sequenced in a previous study (Baiz,
Wood, Brelsford, Lovette, & Toews, 2021). These samples were prepared
with an identical method but sequenced separately from the new samples
included in the current study (n = 24). For phylogenetic analyses
we also included a single golden-cheeked warbler (Setophaga
chrysoparia ) as an outgroup, also published in Baiz et al., (2021).
Genomic DNA was extracted from blood using the Qiagen DNeasy Blood and
Tissue kit following the nucleated blood spin-column protocol with these
minor modifications: we used 75 μL of blood and the 56°C incubation was
performed overnight. All samples were normalized to 2ng/μL and DNA was
sheared with a Covaris S220 to a target insert size of 350bp, according
to the TruSeq Nano protocol. We then prepared sequencing libraries using
the Illumina TruSeq Nano DNA kit and submitted them to the Pennsylvania
State University Genomics Core Facility for sequencing (150nt,
paired-end) on a single NextSeq High Output lane.