160-11 The differing response of cats and dogs to the terminal Pleistocene extinction

Abstract:

The significant extinctions in Earth history have largely been unpredictable in terms of who perished and what traits made them susceptible. This changed in the late Quaternary when human activities began leading to strikingly size-biased extinctions of large-bodied mammals and has accelerated in the modern. Such trophic and body size downgrading is leading to changes in the structure and function of modern ecosystems. Predicting the full effects of biodiversity loss is of obvious importance for effective conservation and management, but many indirect interactions can take decades, centuries or longer to play out. Here, we use the fossil record of the terminal Pleistocene megafauna extinction in the Americas as a proxy for characterizing the consequences of modern biodiversity loss. Using a mammal community in the Edward’s Plateau of Texas, we quantify the isotopic (δ¹³C and δ¹⁵N) and body-size niche before and after biodiversity loss to assess shifts in the ecology and ecological interactions of surviving species. Before the extinction, there was a rich and diverse community quite similar to modern African savannas. In particular, we find regular partitioning of carnivorian dietary isotopic niche with body size; families were largely non-overlapping. Moreover, the largest carnivores were highly specialized. Post-extinction, considerable body size and isotopic niche space were lost, carnivores became more generalized, and some shifted their dietary isotopic niche. We find the ecological roles megafauna play in the earth system are not replicated by smaller-bodied animals. Our work highlights the importance of integrating a paleontological perspective into modern conservation efforts to develop a more synoptic understanding of ecosystems.

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