Mixed-source introductions successfully enhance the genetic diversity of captive forest musk deer (Moschus berezovskii)

Wild Forest musk deer (FMD) has been declining due to continuing poaching and habitat loss. Although captive breeding has increased population numbers, maintaining genetic diversity in these farmed populations has become increasingly urgent and challenging due to depleted wild stocks and loss of genetic diversity from inbreeding in captive populations. Using samples from 683 individuals, we assessed mitochondrial genetic diversity (ATP8-6, Cytb, control region [CR]), structure, and maternal lineage patterns in a newly established ex-situ population (BB; founded 2019 with 44 breeders) and its three founding source populations (PZH, TZL, GL) in western China. Our results demonstrate that the ex-situ population maintains higher nucleotide diversity (π) in ATP8-6 and Cytb than its source populations, while exhibiting comparable haplotype diversity (Hd). Phylogenetic and haplotype network analyses identified three maternal lineages across populations, with the ex-situ population containing representatives of all lineages and showing significant genetic differentiation from at least some founder groups, indicating the mixed-source introduction strategy successfully created a genetically distinct population. Neutrality tests and mismatch distributions suggested historical bottlenecks in baseline populations, whereas the ex-situ population showed signatures of recent admixture and expansion. These findings highlight the potential benefits of mixed-source introductions in enhancing genetic diversity during ex-situ conservation. We recommend long-term genetic monitoring and in-depth analysis of population history to refine translocation strategies and support the long-term viability of FMD under managed care.