Data from: Genotyping-in-Thousands by sequencing reveals marked population structure in Western Rattlesnakes to inform conservation status

Delineation of units below the species level is critical for prioritizing
conservation actions for species at-risk. Genetic studies play an
important role in characterizing patterns of population connectivity and
diversity to inform the designation of conservation units, especially for
populations that are geographically isolated. The northernmost range
margin of Western Rattlesnakes (Crotalus oreganus) occurs in British
Columbia, Canada, where it is federally classified as threatened and
restricted to five geographic regions. In these areas, Western
Rattlesnakes hibernate (den) communally, raising questions about
connectivity within and between den complexes. At present, Western
Rattlesnake conservation efforts are hindered by a complete lack of
information on genetic structure and degree of isolation at multiple
scales, from the den to the regional level. To fill this knowledge gap, we
used Genotyping-in-Thousands by sequencing (GT-seq) to genotype an
optimized panel of 362 single nucleotide polymorphisms (SNPs) from
individual samples (n = 461) collected across the snake’s distribution in
western Canada and neighboring Washington (USA). Hierarchical STRUCTURE
analyses found evidence for population structure within and among the five
geographic regions in BC, as well as in Washington. Within these regions,
11 genetically distinct complexes of dens were identified, with some
regions having multiple complexes. No significant pattern of
isolation-by-distance and generally low levels of migration were detected
among den complexes across regions. Additionally, snakes within dens
generally were more related than those among den complexes within a
region, indicating limited movement. Overall, our results suggest that the
single, recognized designatable unit for Western Rattlesnakes in Canada
should be re-assessed to proactively focus conservation efforts on
preserving total genetic variation detected range wide. More broadly, our
study demonstrates a novel application of GT-seq for investigating
patterns of diversity in wild populations at multiple scales to better
inform conservation management.