Qinghai-Tibetan Plateau and its surrounding slopes constitute a large high-elevation region with a mean elevation exceeding 4,000 m as well as substantial spatial variation in both oxygen content and solar UV radiation. This makes the Qinghai-Tibetan Plateau an ideal region for the study of high-elevation adaptation (HEA).

Groups of organisms that are broadly distributed with respect to diverse elevations provide an excellent opportunity to study the genetic basis of HEA. Since most high-elevation lineages of the Qinghai-Tibetan Plateau appear to have colonized from low-elevation areas. These lineages provide an opportunity for studying recent HEAs and comparing them to ancestral low-elevation alternatives.

In a recent study published in PNAS, a team of scientists from the Kunming Institute of Zoology of the Chinese Academy of Sciences (CAS) compared four frogs (three species of Nanorana and a close lowland relative) and four lizards (Phrynocephalus) that inhabit a range of elevations on or along the slopes of the Qinghai-Tibetan Plateau and examined the gradual accumulation of HEA at increasing elevations.

They found that many adaptations to high-elevations appear to arise gradually and evolve continuously with increasing elevational distributions. Also, they discovered that numerous related functions, especially DNA repair and energy metabolism pathways, exhibit rapid change and continuous positive selection with increasing elevations.

Interestingly, although the two studied genera are distantly related, they exhibit numerous convergent evolutionary changes, especially at the functional level.

The findings indicated that species groups distributed along a broad elevational gradient provide a more powerful system for testing adaptations to high elevation environments in contrast to studies that compare only pairs of high- versus low-elevation species.

This work was supported by grants from the Strategic Priority Research Program (B) Grant of CAS, National Natural Science Foundation of China Grant, the Animal Branch of the Germplasm Bank of Wild Species of CAS (the Large Research Infrastructure Funding), and the Youth Innovation Promotion Association, CAS.