New Insights into the Variation and Admixture of the Cave-Dwelling Spider Trogloneta yunnanensis in South China Karst

SIMPLE SUMMARY: The subterranean fauna is an important component of global biodiversity. However, research on the subterranean fauna of the Yunnan–Guizhou Plateau in Southwest China, one of three important karst landforms in the world, is limited. In this study, we performed a population genetic analysis and reconstructed the phylogenetic tree of six populations of Trogloneta yunnanensis in South China Karst. The results showed that there was high genetic divergence among six populations, and the divergence of these six populations can be traced back to the late Pleistocene. Our results suggested that isolation was a pivotal factor affecting the biodiversity of cave faunas, and the biodiversity of cave-dwelling faunas needs to be studied as soon as possible. ABSTRACT: Subterranean karst caves can contain unexpected biodiversity, but few studies related to spider population genetics have been conducted in the karst area of Southern China. In this study, we investigated the population genetic structure of Trogloneta yunnanensis (Song & Zhu, 1994) based on 73 spider samples from six underground populations in South China Karst. Population genetic structure analysis showed a clear divergence (F(ST) > 0.9 and Nm < 0.05) among populations according to mitochondrial genes. The phylogenetic gene tree constructed by BI and ML methods recovered six geographic clades. Divergence time estimation indicated that the divergence of these six populations can be traced back to the late Pleistocene. We supposed that the geographic isolation led to the extreme population structure. According to this study and previous studies about troglobites living in this region, the subterranean habitats of the Yunnan-Guizhou Plateau may contain many organisms with similar genetic structures. The subterranean biodiversity in the karst area of Southern China needs to be re-evaluated and protected.