High Warming Restricts the Growth and Movement of a Larval Chinese Critically Endangered Relict Newt

Amphibians are the most threatened vertebrates, yet their resilience in relation to growth and locomotor performance with rising temperatures remains poorly understood. Here, we chose a critically endangered amphibian-the Chinhai spiny newt (Echinotriton chinhaiensis)-as the study species and set four water temperature gradients (20 °C, 24 °C, 28 °C, and 32 °C) to simulate climate changes. The thermal performance to climate warming was quantified by measuring morphometric parameters, basal metabolic rate (oxygen consumption rate), and the locomotor performance of Chinhai spiny newt larvae. We found that the optimal temperature range for Chinhai spiny newt larvae is 24-28 °C. Within the temperature range of 24-28 °C, the growth, oxygen consumption rate, and locomotor performance of the larvae were positively correlated with temperature. High temperatures inhibited larval growth, oxygen consumption rate, and locomotor performance, and the temperature threshold was 32 °C. In addition, Chinhai spiny newt larvae are more sensitive to acute temperature changes, meaning that climate-driven extreme events (e.g., heatwaves and droughts) pose significant threats to their larvae. The optimal temperature range obtained from this study could guide artificial breeding and early warming; future studies should integrate controlled temperature fluctuations in order to understand the thermal adaption of this threatened species.