Biodiversity and distribution patterns of Triplophysa species in the northeastern margin of the Tibetan Plateau

Abstract

The northeastern region of the Tibetan Plateau is a region with high genetic diversity for endemic species. To comprehensively document the patterns of diversity and the distribution of Triplophysa species in this area, we probed the allocation of Triplophysa species using field surveys from 2012 to 2015. We found that areal shrinkage and fragmentation had occurred in some species. Species richness in this area was uneven. But the middle to upper reaches of the Heihe River, Datong River and Taohe River were uncommon areas with high species-richness and high biodiversity. Along altitudinal gradients, species richness presented a unimodal pattern and peaked at mid-elevations (2,200–2,400 m), which was the transition area between two community zones with high species richness. The unimodal pattern fit Lomolino’s prediction regarding species density and altitude. Biodiversity indices displayed uniform patterns with species richness and elevation. Consistent with most studies, the unimodal shape may be the universal pattern of biodiversity distribution along elevational gradients in the Tibetan Plateau and its adjacent highlands. The intermediate elevational regions should be conservation priorities.