Microsatellite data for Bull Trout

Freshwater ecosystems are negatively impacted by a variety of
anthropogenic stressors, with concomitant elevated rates of population
decline for freshwater aquatic vertebrates. Because reductions in
population size and extent can negatively impact genetic diversity and
gene flow, which are vital for sustained local adaptation, it is important
to measure these characteristics in threatened species that may yet be
rescued from extinction. Across its native range, Bull Trout (Salvelinus
confluentus) extent and abundance are in decline due to historic
overharvest, invasive nonnative species, and habitat loss. In Alberta’s
Eastern Slope region, populations at the range margin have progressively
been lost, motivating us to better understand the amount and distribution
of genetic variation in headwater habitats and some downstream sites where
they continue to persist. Across this region, we sampled 431 Bull Trout
from 20 sites in the Athabasca and Saskatchewan River basins and assayed
10 microsatellite loci to characterize within- and among-population
genetic variation. The Saskatchewan and Athabasca River basins contained
similar levels of heterozygosity but were differentiated from one another.
Within the Athabasca River basin, five genetically differentiated clusters
were found. Despite the evidence for genetic differentiation, we did not
observe significant isolation-by-distance patterns among these sites. Our
findings of ample genetic diversity and no evidence for hybridization with
non-native Brook Trout in headwater habitats provide motivation to
ameliorate downstream habitats and remove anthropogenic barriers to
connectivity towards the goal of long-term persistence of this species.