Continued collaboration of ex situ and in situ programs is critical for the genetic sustainability of the endangered Rana pretiosa

Abstract

Retaining sufficient genetic variation for both short and long-term sustainability is a chief aim of ex situ programs for threatened species. Conservation breeding and reintroduction programs exist but oftentimes little is known about the genetic variation of in situ or ex situ populations. We collected genetic samples from both wild and zoo populations of Canada’s most endangered anuran, the Oregon Spotted Frog (Rana pretiosa) to compare genetic diversity (observed and expected heterozygosity), inbreeding coefficients (FIS), effective population sizes (Ne) and population structure using single-nucleotide polymorphisms (SNPs). We found low diversity in situ and lower diversity ex situ, with positive inbreeding coefficients indicating assortative mating in both wild and zoo populations. Ex situ breeding programs that allowed free mate choice retained more genetic variation compared to those where breeding groups were pre-determined. Mixed source zoo populations were less differentiated from their wild source populations than the latter were among themselves, indicating sufficient representation of wild populations in zoo populations. The patterns we uncover support continued collaboration of ex situ and in situ endeavours as supplementation will likely be required for the long-term viability of the very wild populations the zoos rely on for genetic sustainability.