Shifts in salamander body size associated with 60 years of climate change

Climate change impacts body size, a fundamental trait central to energetics and reproductive success. Most studies on body size shifts in response to climate change have focused on temperature, with smaller sizes expected under warming. However, precipitation has received less attention, even though water and heat balance interact to impact body size. Precipitation changes may be particularly important for wet-skinned amphibians. We examined body size shifts in 10 plethodontid salamander species in the Balsam Mountains, Virginia, USA. Using historical data (1957-1959) as a baseline, we resurveyed salamanders (2021 and 2023) to assess how temperature and precipitation shifts have influenced body size. We hypothesized warmer, wetter conditions would reduce body sizes across species. Over 60 years, temperatures warmed across elevation, while precipitation increased more at higher compared to lower elevations. After accounting for phylogeny, warming generally reduced body size, with temperature effects amplified by increased precipitation at high elevations. However, the direction and magnitude of body size shifts were species-specific, indicating that size shifts are a complex interplay of environmental factors and species traits. Our findings highlight the importance of considering interacting climate variables when assessing responses to environmental change, particularly in montane ecosystems.