Genetic rescue leads to higher fitness as a result of increased
heterozygosity across animal taxa
- Julia Clarke,
- Adam Smith,
- Catherine Cullingham
Abstract
Biodiversity loss has reached critical levels due in part to
anthropogenic habitat loss and degradation. These landscape changes are
particularly damaging as they can result in fragmenting species
distributions into small and isolated populations, resulting in limited
gene flow, population declines and reduced adaptive potential. Genetic
rescue, the translocation of individuals for the purpose of restoring
gene flow, has been shown to produce promising results for fragmented
populations but remains relatively under-used due to a lack of long-term
data and monitoring of genetic rescue attempts. To promote a better
understanding of genetic rescue and its potential risks and benefits
over the short-term, we reviewed and analyzed all genetic rescue
attempts to date to identify whether genetic diversity increases
following rescue, and if this change is associated with increased
fitness. Our review identified only 19 genetic rescue studies, that
included experimental, natural, and conservation motivated, with the
majority of studies being on mammals. We used a Bayesian meta-analytical
approach to examine the relationship between fitness and genetic
diversity. We found that genetic diversity, as represented by
heterozygosity, was a positive predictor of population fitness, and this
relationship extended to the third-generation post-rescue. These data
suggest a single introduction can have lasting fitness benefits,
supporting translocation as another tool to ensure conservation success.
Given the limited number of studies with long-term data, we echo the
need for genetic monitoring of translocations to ascertain whether
genetic rescue may also limit the loss of adaptive potential in the
long-term.