Unrecognized diversity, genetic structuring, and phylogeography of the genus Triplophysa (Cypriniformes: Nemacheilidae) sheds light on two opposite colonization routes during Quaternary glaciation that occurred in the Qilian Mountains.

In recent years, the influence of historical geological and climatic events on the evolution of flora and fauna in the Tibetan Plateau has been a hot research topic. The Qilian Mountain region is one of the most important sources of biodiversity on the Qinghai-Tibet Plateau. Many species existed in the region during the Pleistocene glacial oscillation, and the complex geographical environment provided suitable conditions for the survival of local species. The shrinkage, expansion, and transfer of the distribution range and population size of species have significant effects on genetic diversity and intraspecific differentiation. To reveal the effects of geological uplift and climate oscillation on the evolution of fish populations in the Qilian Mountains, we investigated the genetic structure, phylogenetic relationship, and phylogeographical characteristics of genus Triplophysa species in the Qilian Mountains using the mitochondrial DNA gene (COI), three nuclear genes (RAG1, sRH, and Myh6) and 11 pairs of nuclear microsatellite markers. We collected 11 species of genus Triplophysa living in the Qilian Mountains, among which Triplophysa hsutschouensis and Triplophysa papillosolabiata are widely distributed in the rivers on the northern slope of the Qilian Mountains. There was a high degree of lineage differentiation among species, and the genetic diversity of endemic species was low. The different geographical groups of T. papillosolabiata presented some allogeneic adaptation and differentiation, which was closely related to the changes in the river system. Except for the population expansion event of T. hsutschouensis during the last glacial period of the Qinghai-Tibet Plateau (0.025 MYA), the population sizes of other plateau loach species remained stable without significant population expansion. Starting from the east and west sides of the Qilian Mountains, T. hsutschouensis, and T. papillosolabiata showed two species colonization routes in opposite directions. The geological events of the uplift of the Qinghai-Tibet Plateau and the climatic oscillation of the Quaternary glaciation had a great influence on the genetic structure of the plateau loach in the Qilian Mountains, which promoted the genetic differentiation of the plateau loach and formed some unique new species. The results of this study have important guiding significance for fish habitat protection in the Qilian Mountains.

Characterization of the complete mitochondrial genome of Gymnocypris chilianensis (Teleostei: Cypriniformes: Cyprinidae).

The complete mitochondrial DNA sequence of Gymnocypris chilianensis was determined and analyzed. The mitogenome of G. chilianensis is 16,667 bp long, containing 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 2 non-coding regions: control region (D-loop) and origin of light-strand replication (OL). The gene order of mitogenome is identical to that observed in most other vertebrates. The complete mitogenome sequence information of G. chilianensis can provide useful data for further studies on molecular systematic, taxonomic status, stock evaluation and conservation genetics.

Sequence and organization of the complete mitochondrial genome of Schizothorax davidi (Teleostei: Cypriniformes: Cyprinidae).

In this study, we determined the complete mitochondrial genome sequence of Schizothorax davidi. The length of the genome is 16,577 bp, which contains 13 protein coding genes, 22 transfer RNAs, two ribosomal RNAs, and two non-coding regions: control region (D-loop) and origin of light-strand replication (OL). The complete mitochondrial DNA sequence of S. davidi provides useful genetic markers for the studies on molecular systematic, population genetics, and phylogeography.