Conservation units and metapopulation structure inform recovery goals in
a threatened species
Abstract
Monitoring genetic parameters is important for setting effective
conservation and management strategies, particularly for small,
fragmented, and isolated populations. Small populations face increased
rates of genetic drift and inbreeding, which increase extinction risk
especially when gene flow is limited. Here, we applied a
Genotyping-in-Thousands by sequencing (GT-seq) panel to inform recovery
action for the northern Idaho ground squirrel (Urocitellus brunneus),
listed as threatened under the U.S. Endangered Species Act. We evaluated
genetic diversity, structure, connectivity, and effective population
size to address species recovery goals. We delineated 15 conservation
units: (1) three evolutionarily significant units that represent
long-term population structure and evolutionary history, (2) nine
management units that reflect current demographic connectivity and
restrictions to gene flow, and (3) three adaptive units that capture
adaptive differentiation across the species range. Effective population
sizes per management unit were small overall (mean 38.16, range
2.3-220.9), indicating that recovery goals have not been reached. Our
results suggest that connectivity within evolutionarily significant
units should be maintained through the restoration of dispersal
corridors. We recommend further sampling of subpopulations that harbor
unique adaptive differentiation and that are geographically isolated to
refine our understanding of adaptive variation. We recommend ongoing
genetic monitoring with the same GT-seq marker panel to detect
dispersal, assess effective population size, monitor the effects of
inbreeding, and evaluate adaptive differentiation to monitor the effects
of management action and environmental change. This study provides an
illustration of how genetic and genomic tools can inform management and
assess recovery goals for a threatened species.