Understanding how populations adapt to different thermal environments is important for biodiversity conservation in the context of recent global warming.

In a recent study published in Scientific Reports, researchers from Institute of Hydrobiology of Chinese Academy of Sciences investigated the regional differences in thermal adaptation of a cold-water fish Rhynchocypris oxycephalus, and found that populations from southern region are more sensitive to global warming.

Over the years, many studies have found intraspecific differences in thermal tolerance in eurythermal species, yet little is known to cold-water species.

Using critical thermal methodology, researchers found the thermal tolerance range and thermal tolerance polygon area of southern population (Hangzhou, Zhejiang Province) were narrower than the northern (Gaizhou, Liaoning Province) population, indicating populations from southern region were possibly more vulnerable.

Further transcriptomic analysis revealed that the northern population expressed more temperature responding genes (TRGs) than the southern population under high temperature treatment (29°C), which is in agreement with their higher thermal tolerance.

Some TRGs (e.g. heat shock protein) showed higher expression in the southern population under control condition (19°C), suggesting individuals from southern region possibly have already responded to the present higher environmental temperature pressure.

"Our study proposed conservation efforts should pay more attention to southern populations to avoid local extinction," said Prof. LIU Huanzhang, principal investigator of this study.

This work was supported by grants from the Strategic Priority Research Program of Chinese Academy of Sciences and the National Natural Science Foundation of China.