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

Abstract

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 2of24 | DU et al.

Mitochondrial genome data provide insights into the phylogenetic relationships within Triplophysa dalaica (Kessler, 1876) (Cypriniformes, Nemacheilidae)

“…In the divergence-time analysis, these three clades were estimated to diverged 7–10 Ma. The divergence is relatively deep compared to the intraspecies differentiation in other Triplophysa species ( Hu et al 2020 , 2022 ; Wu et al 2020 ; Du et al 2023 ), suggesting they might be divided into several potential subspecies, or even species, which need extra analyses including morphology and phylogeny with more samples. These results offer insights into the evolutionary history of T. dalaica , as well as the correlation between the change of population and historical climate and geological events.…”

“…Due to their widespread distribution, species of Triplophysa exhibit adaptability to diverse habitats, including cold environments, hypoxia, and saline waters. In recent years, multiple aspects including the phylogenetic relationships among Triplophysa species ( Wang et al 2016 , 2023 ; Chen et al 2019 ; Wu et al 2020 ), phylogeography ( Hu et al 2020 , 2022 ; Zhong et al 2022 ; Du et al 2023 ), patterns of population differentiation ( Zhou et al 2021b ; Jin et al 2022 ), and the adaptations to various habitats ( Chen et al 2020b , 2020a ; Zhang et al 2023 ) have been studied.…”

Population structure and adaptability analysis of Schizothorax o’connori based on whole-genome resequencing

“…Numerous studies have shown that ancient climate and geological events might be important factors affecting the current geographical distribution and genetic differentiation of species in the Qinghai-Tibet Plateau [ 58 – 61 ]. In this study, the effective population of S. o’connori decreased for a short time in the late accelerated uplift stage of the Qinghai Tibet Plateau (~ 1 million years ago) and the Quaternary Ice Age [ 24 , 62 , 63 ].…”