Data from: Population genomic diversity and structure at the discontinuous southern range of the Great Gray Owl in North America

Species' distributions are often discontinuous near the edge of the
range where the environment may be more variable than the core of the
range. Range discontinuity can reduce or cut off gene flow to small
peripheral populations and lead to genetic drift and subsequent loss of
genetic diversity. The southern extent of the Great Gray Owl (
Strixnebulosa) range in North America is discontinuous, unlike their
northern core range across the boreal forests. We sampled owls from five
different locations on the periphery of the range across the western US
(Wyoming, Idaho, California, northern Oregon, and southern Oregon) to
investigate genetic population structure and genetic diversity. Using a
reduced-representation genomic sequencing approach to genotype 123
individuals at 4,817 single nucleotide polymorphic loci, we identified
four genetically differentiated populations: California, southern Oregon,
northern Oregon, and Wyoming and Idaho grouped together as a single Rocky
Mountain population. The four genetically differentiated populations of
Great Gray Owls identified in this study display high differentiation and
low genetic variation, which is suggestive of long-term isolation and lack
of connectivity, potentially caused by range discontinuity. The
populations that lack habitat connectivity to the rest of the breeding
range (i.e. those in California and Oregon) had lower genetic diversity
than the Rocky Mountain population that is connected to the core of the
range. These factors and other risks (such as disease and human-caused
mortality) heighten susceptibility of these range-edge populations to
future habitat and climate changes, genetic diversity erosion, and
potential extinction vortex. For these reasons, protecting and monitoring
this species on the southern edge of their range is vital.