Phylogeographical and Morphological Analyses of Triplophysa stenura (Cypriniformes: Nemacheilidae) from the Three Parallel Rivers Region, China.

Qiu Ren, Jun-Xing Yang, and Xiao-Yong Chen (2018) Triplophysa stenura is an indigenous and widely distributed loach in the Qinghai-Tibet plateau and adjacent Three Parallel Rivers region of China. Morphological and phylogenetic analyses were performed in order to explore the genetic and morphological variation in T. stenura populations from different geographic regions and infer the divergence time and relationships between populations from the three rivers (Jinsha River, Nu River and Lancang River). Two mitochondrial genes (Cyt b, D-Loop) and 35 morphological characters were selected for genetic and morphological analyses, respectively. Phylogenetic and network analyses reveal that T. stenura is a single lineage with three well supported clades strictly corresponding to specific river systems. Divergence time analysis suggests that the divergence of T. stenura and formation of the Three Parallel Rivers are closely associated with the Kun-Huang Movement (1.1- 0.6 MYA), which lead to the uplift of the Qinghai-Tibet plateau. AMOVA reveals that there is moderate genetic differentiation among populations. Results from ANOVA suggest that several morphological characters show significant variation among populations and drainages. Descriptive morphological variation (e.g., color pattern) in different populations of T. stenura clarifies a set of characters that can be used to accurately identify members of this group in the future. We conclude that T. stenura has moderate population genetic structure and character variation in this study area and the divergence and evolution of T. stenura is associated with the uplift of the Qinghai-Tibet plateau.