The relationship between climate and adult body size in redback salamanders (Plethodon cinereus)

Abstract

Several biogeographic studies of salamanders have described relationships between salamander body size and climate. We specifically selected Plethodon cinereus as a widely distributed species that was well represented in museum collections to investigate the effects of warming climate on adult body size. We found a positive correlation between mean maximum July temperature and body size, and a negative correlation between precipitation of the driest month and body size. Surface-collected adult P. cinereus were 2.3% larger in warmer counties on the coastal plain compared with cooler counties in the Appalachian Mountains. We compared salamanders collected between 1950 and 1970 versus those collected between 1980 and 2000 and found that body size increased 1.8% in counties on the coastal plain where mean maximum July temperatures had also increased by 0.5–1.2 °C. Warming temperatures alone, however, did not adequately account for the observed size increases, because body size also increased 1.3% in places that experienced less than 0.25 °C warming, but that difference was not statistically significant.