Late Pleistocene megafauna extinction leads to missing pieces of ecological space in a North American mammal community

Authors

Felisa A. Smith, University of New MexicoFollow
Emma A. Elliott Smith, University of New Mexico
Amelia Villaseñor, University of ArkansasFollow
Catalina P. Tomé, University of Nebraska-LincolnFollow
S. Kathleen Lyons, University of Nebraska - LincolnFollow
Seth D. Newsome, University of New MexicoFollow

Date of this Version

2022

Citation

PNAS 2022 Vol. 119 No. 39 e2115015119

doi:10.1073/pnas.2115015119

Comments

This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0

Abstract

The conservation status of large-bodied mammals is dire. Their decline has serious consequences because they have unique ecological roles not replicated by smaller-bodied animals. Here, we use the fossil record of the megafauna extinction at the terminal Pleistocene to explore the consequences of past biodiversity loss. We characterize the isotopic and body-size niche of a mammal community in Texas before and after the event to assess the influence on the ecology and ecological interactions of surviving species (>1 kg). Preextinction, a variety of C₄ grazers, C₃ browsers, and mixed feeders existed, similar to modern African savannas, with likely specialization among the two sabertooth species for juvenile grazers. Postextinction, body size and isotopic niche space were lost, and the δ¹³C and δ¹⁵N values of some survivors shifted. We see mesocarnivore release within the Felidae: the jaguar, now an apex carnivore, moved into the specialized isotopic niche previously occupied by extinct cats. Puma, previously absent, became common and lynx shifted toward consuming more C₄-based resources. Lagomorphs were the only herbivores to shift toward C₄ resources. Body size changes from the Pleistocene to Holocene were species-specific, with some animals (deer, hare) becoming significantly larger and others smaller (bison, rabbits) or exhibiting no change to climate shifts or biodiversity loss. Overall, the Holocene body-size-isotopic niche was drastically reduced and considerable ecological complexity lost. We conclude biodiversity loss led to reorganization of survivors and many “missing pieces” within our community; without intervention, the loss of Earth’s remaining ecosystems that support megafauna will likely suffer the same fate.