Understanding the Effects of Climate Change on the Distributional Range of Plateau Fish: A Case Study of Species Endemic to the Hexi River System in the Qinghai–Tibetan Plateau.

Prediction of species' potentially suitable distribution areas and their range shifts under future climate change has long been the focus of macroecology and biogeography. Gymnocypris chilianensis of Schizothoracinae and Triplophysa hsutschouensis of Triplophysa are isolated to the Shiyang, Heihe, and Shule Rivers of the Hexi River system, listed from east to west, along the northeastern part of the Qinghai–Tibetan Plateau (QTP). This spatial distribution provides a valuable set of conditions for investigating patterns of habitat suitability and potential impacts of accelerated plateau climate change on endemic plateau fish species. Here, we employed the maximum entropy (MaxEnt) model to first evaluate potentially suitable habitats of the two species and identify the primary impact factors under the current climate based on occurrence records and environmental variables; then, we predicted changes in suitable habitat areas and distribution centers under two representative concentration pathways (RCPs), 2.6 and 8.5, for the future (2050 and 2070). The results showed that annual precipitation and altitude were the two most important environmental factors predicting the suitable habitat of G. chilianensis and T. hsutschouensis. The areas of suitable habitat for G. chilianensis and T. hsutschouensis experienced a sequential westward decrease from the Shiyang River towards the Heihe and Shule Rivers under the current climate conditions. Under future climate changes, the areas of the potential geographical distribution of G. chilianensis and T. hsutschouensis were concentrated eastward towards the Shiyang River, the area of the species' ancestral origins. Suitable habitat centers of the two species shifted eastward from the Heihe River to the Shiyang River and higher altitude areas. Additionally, G. chilianensis showed a greater reduction in suitable habitat and greater eastward range shift compared to T. hsutschouensis. These findings provide empirical evidence that accelerated climate change on the QTP has severe consequences for endemic populations with restricted and isolated habitats. This study demonstrates that different plateau fish have similarities and differences in their responses to climate change. Our findings also highlight that the effects of climate change must be incorporated into the integrated conservation plans for fish species on the QTP and its adjacent areas. [ABSTRACT FROM AUTHOR]