Challenges of introgression in conservation: non-invasive sampling and surveillance of genetic diversity of in-situ and ex-situ populations of the Critically Endangered Wild Camel in Mongolia

Hybridisation is a naturally occurring evolutionary process important in the facilitation of both adaptation and speciation but is often considered an extinction risk for threatened species. Anthropogenic novel distributions of species, exacerbated by habitat destruction and climate change, accelerates the rate, frequency, and extent to which populations interact, thereby increasing the opportunity for hybridisation. Hybridisation can be considered a threat to, or an opportunity for, species' population viability, and this dilemma creates challenges in conservation management. We used non-invasive sampling combined with nuclear and mitochondrial DNA markers to gain a greater understanding of the extent and source of introgression and levels of genetic diversity in the critically endangered Wild camel, Camelus ferus, in both the in-situ population and the ex-situ insurance population in Mongolia. Our results show evidence of both nuclear, mitochondrial and historic introgression of Bactrian camel, Camelus bactrianus, genes in the C. ferus population in-situ, and in some individuals within the ex-situ herd. We also show reduced heterozygosity and elevated inbreeding in the in-situ population and reveal similar characteristics in the ex-situ herd. Our findings illustrate that, whilst the global conservation community currently adopts largely arbitrary thresholds for what is an acceptable level of introgression, a detailed genetic perspective is crucial in increasing our understanding of hybridisation in conservation and is an important first step towards identifying options for conservation management.