The late Quaternary fossil record of mole salamanders in central Texas reveals range shifts and responses to environmental change

Abstract Understanding biotic responses to environmental changes will help identify extinction risks and direct conservation efforts to mitigate negative effects associated with anthropogenic-induced environmental changes. Here we use the Quaternary fossil record of mole salamanders ( Ambystoma ) from the southwestern United States and northern Mexico to reveal geographic patterns of extirpation since the Pleistocene. Ambystoma are known to have previously inhabited regions of central Texas on the Edwards Plateau; however, they are largely absent from the region today. We used a well-dated fossil record of Ambystoma from Hall’s Cave combined with other fossil sites in the region to deduce why Ambystoma was ultimately extirpated from the Edwards Plateau and to test hypotheses related to temperature-driven body-size changes in line with the temperature–size rule. We propose that Ambystoma was likely extirpated from the region due to changing temperature and precipitation regimes that caused increased mortality and disruptions to breeding and larval development. We found some support for decreased body size in Ambystoma with increased temperature during the late Pleistocene, suggesting that body size may be an important feature to monitor in modern populations of Ambystoma as salamanders become subjected to increasingly hotter temperatures in the coming decades.