Modeling brook trout genetic response to population isolation

Brook trout (Salvelinus fontinalis) reside in a range of habitats including headwater streams where populations may become periodically isolated.  Demographic consequences of population isolation include increased potential for localized extinction. Genetic consequences for population isolation, or populations of sustained small numbers, include increasing susceptibility to inbreeding, the expression of negative fitness traits, and overall loss of genetic variability, which may increase the risk of localized extinction.  Reestablishment of connectivity with larger populations through periodic gene flow into these small populations may act to offset loss of genetic diversity. 

Restoring population connectivity and degraded headwater habitats, especially those that historically harbored wild brook trout populations has been a focus of restoration efforts.  To understand the degree of genetic isolation among headwater brook trout populations, we examined how variability in connectivity between brook trout populations in three different geographic areas has resulted in the partitioning of genetic variation within each population group.  Population isolation within each group varies, either due to natural (waterfalls and logjams) or anthropogenic (dams, pollution) barriers.  Interpretation of genetic and habitat information for each population group was used to develop a predictive model to estimate the genetic response of brook trout to population isolation.