The impact of large terrestrial carnivores on Pleistocene ecosystems.
Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator-prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes.
Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095; bvanval@ucla.edu.
Blaire
B
Van Valkenburgh
College of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, United Kingdom; Centre for African Conservation Ecology, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa; Centre for Wildlife Management, University of Pretoria, Pretoria, South Africa;
Matthew W
http://orcid.org/0000-0002-5574-1653
MW
Hayward
Trophic Cascades Program, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331;
William J
WJ
Ripple
Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, United Kingdom;
Carlo
C
Meloro
Department of Biology, Duke University, Durham, NC 27708-0338.
V Louise
VL
Roth
D000349:Africa; D000569:Americas; D063147:Animal Distribution; D000818:Animals; D001208:Asia; D044822:Biodiversity; D049628:Body Size; D002335:Carnivora / Q000502:physiology*; D060435:Carnivory; D017753:Ecosystem; D005060:Europe; D053476:Extinction, Biological; D005544:Forecasting; D005580:Fossils; D056665:Mammoths; D056666:Mastodons; D011156:Population Density; D011235:Predatory Behavior
Carnivora; hypercarnivore; megafauna; megaherbivore; predator