Effect of predation on prey abundance and survival in Plio-Pleistocene mammalian communities

摘要

Question: Does predatory pressure affect the abundance and survival of prey species in extinct communities? Data studied: Presence-absence data and body sizes of large mammals (partitioned into predators and prey) in Plio-Pleistocene Italian PaleoCommunities (PCOMs). Transformed variables: (1) Species' occupancy: number of presencesumber of sites. (2) ADI: the index of disparity (ADI) reflects the relative abundance of a prey species in a PCOM. (3) Predatory pressure on a prey species: the proportion of predators in a given PCOM that are expected to feed on it. (4) Nestedness: the extent to which rare species occur only in the species-rich sites of a PCOM. Search method: For each PCOM, the effect of preservation biases on species' occupancy was assessed by a nestedness analysis. The ADI was computed for each prey species in each PCOM. Predatory pressure was calculated for each prey species. We used linear regression to test the effect of predatory pressure on ADI. Non-parametric correlation was performed to determine the effect of ADI on species survival. Results: Species prone to greater pressure appear at fewer sites than would be expected for their size alone. The relationship is limited to rare species only. Taphonomy does not explain this disparity. Abundant species survive longer than rare species. Conclusion: Predation controls abundance and local survival of rare species. In contrast, it does not affect abundant species.