Behavioral and Historical Processes Jointly Maintain Genetic Connectivity in Fragmented Chinese Water Deer...

Habitat fragmentation poses a major threat to endangered species by isolating populations and disrupting gene flow. The vulnerable Chinese water deer (Hydropotes inermis) in northeastern China offers a critical case for understanding how fragmented landscapes influence genetic viability. Through noninvasive sampling of 286 individuals genotyped at 11 microsatellite loci and mitochondrial markers, we evaluated genetic diversity, structure, and dispersal dynamics. Although microsatellite diversity was moderate (mean H _e = 0.661), positive F _is values indicated inbreeding or nonrandom mating within local groups. Surprisingly, population genetic structure was extremely weak (overall F _st = 0.008), and contemporary gene flow remained high, revealing that connectivity persists despite extensive habitat fragmentation. Our analyses show that this connectivity is maintained primarily through female-biased dispersal-a striking contrast to the male-biased dispersal typical of most artiodactyls. Higher female assignment indices and a greater proportion of females identified as recent dispersers consistently supported this pattern. Mitochondrial data further suggested a historical population expansion, providing context for the current genetic composition. These findings indicate that female-mediated movement functions as a natural genetic rescue mechanism, mitigating the genetic drift and inbreeding expected in small, isolated populations. From a conservation perspective, this behavioral adaptation is essential for sustaining population viability. Effective management should therefore prioritize the protection and restoration of habitat corridors that facilitate female movement, ensuring that natural dispersal processes continue to maintain genetic health and long-term persistence of Chinese water deer in northeastern China.