Elevation shapes thermal breadth and climate sensitivity in Moltrecht's treefrog tadpoles

Global climate change causes rising annual temperatures and an increase in extreme climate events, posing higher risks to organisms. Understanding the thermal tolerance of organisms is therefore crucial to evaluate the temperature limits they can withstand. Previous studies have hypothesized that species thriving in regions with higher climatic variability tend to have broader thermal tolerance breadth to adapt to such environments, a concept known as the climate variability hypothesis. However, few studies have explored whether different populations of the same species, distributed across varying environments, follow this trend. In this study, we examined the critical thermal tolerance abilities and recorded the microclimates of Moltrecht's green treefrog (Zhangixalus moltrechti) tadpoles across different elevations. We aimed to test the climate variability hypothesis and assess the plasticity of their upper and lower thermal tolerance limits. Our results revealed that tadpoles from higher elevations exhibit a broader thermal tolerance breadth, with elevation primarily influencing their critical thermal minimum. Additionally, the plasticity of cold tolerance was greater than that of heat tolerance. Our study highlights that even within the same species, populations in different environments face distinct threats from climate change. Notably, global warming poses a greater risk to low-elevation populations.