Before, during and after megafaunal extinctions: Human impact on Pleistocene-Holocene trophic networks in South Patagonia

PIRES, MATHIAS M.; RINDEL, DIEGO; MOSCARDI, BRUNO; CRUZ, LIVIA R.; GUIMARÃES, PAULO R.; DOS REIS, SERGIO F.; PEREZ, S. IVAN

QUATERNARY SCIENCE REVIEWS

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2020 vol. 250 p. 1 - 11

0277-3791

Worldwide extinctions of large terrestrial vertebrates in the late Pleistocene provide insight on howhumans reshape ecological communities. Understanding the ecological causes and consequences ofmegafaunal extinctions requires integrating approaches to reconstruct the ecological communities fromthe past. Here, we combined archeological and paleontological evidence with network analyses to understandthe changes in ecological communities from late Pleistocene to the Holocene in South Patagonia,the last continental region where the encounter between humans and extinct megafaunaoccurred. The zooarcheological record suggests humans would have interacted mainly with large-bodiedspecies, which comprise a small subset of the available prey. Accordingly, using network reconstructionsand structural analyses, we found that human arrival would have produced minor changes in the overallstructure of trophic networks. However, those few novel interactions established by humans would havecreated multiple indirect paths among megafaunal species. Indirect paths are the route for indirect effectssuch as competition and increase the vulnerability of interaction networks to perturbations. Afterthe extinctions of most of the megafauna, the impoverished network became structurally simpler anddensely connected. Our reconstructions of past trophic networks show that multiple indirect effects,potentially contributing to extinctions, can emerge even from a limited number of novel interactions andillustrate how network organization can affect and be affected by extinctions events