Diverged Populations Admixture Bolsters Genetic Diversity of a New Island Dibbler (Parantechinus apicalis) Population, but Does Not Prevent Subsequent Loss of Genetic Variation

Abstract

Translocating individuals from multiple source populations is one way to bolster genetic variation and avoid inbreeding in newly established populations. However, mixing isolated populations, especially from islands, can potentially lead to outbreeding depression and/or assortative mating, which may limit interbreeding between source populations. Here, we investigated genetic consequences of mixing individuals from two island populations of the dibbler (Parantechinus apicalis) in an island translocation. Despite a high level of genetic divergence between the source populations (F_ST ranges 0.33–0.64), and significant differences in body size, individuals with different ancestries were able to successfully interbreed in captivity and in the wild. However, the genetic contributions from each source population were unequal initially despite each of the source populations contributing an equal number of founders. Mating success of captive animals based on the pedigree suggests that this bias toward one source population was due to founder mortality and the mating success of younger and heavier animals. Nevertheless, genetic contributions in the translocated population became equal over time with no parental purebreds, suggesting an extreme excess of hybrids across multiple years. While genetic variation in the translocated population was comparable or higher than the source populations, the increase was short-lived. Genetic composition of captive animals may not reflect what happens in the wild. These changes post-translocation highlight the need for continued genetic monitoring.