Genetic decline and conservation challenges of the yiwu salamander (Hynobius yiwuensis)

Maintaining genetic variability is widely regarded as essential for ensuring the adaptive capacity and long term persistence of threatened species in changing environments. Native to Zhejiang Province in China, Hynobius yiwuensis is a threatened amphibian species that has undergone severe population reductions, primarily attributed to environmental degradation and the loss of suitable habitats. In this study, we applied transcriptome derived microsatellite markers (SSRs) to evaluate genetic diversity and population structure in five H. yiwuensis populations from Zhejiang Province. We identified 9,817 SSR loci in total, of which mononucleotide repeats occurred most frequently. Genetic diversity analyses revealed moderate polymorphism, with an average observed heterozygosity (Ho) of 0.408 and expected heterozygosity (He) of 0.502 across the populations. Among the examined populations, genetic diversity was highest in Lihuang (He = 0.5802) and lowest in Huantan (He = 0.4000), indicating regional differences in heterozygosity levels. Population bottleneck tests indicated genetic constriction, particularly in the Huantan population, significantly increasing extinction risks. The study also found substantial genetic differentiation between island and mainland populations, with the Mahuangshan population being highly isolated. These results underscore the urgency of implementing targeted conservation efforts to preserve the genetic integrity of H. yiwuensis and provide insights for the management of other endangered amphibians.