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Oecologia. 2014 Aug;175(4):1247-56. doi: 10.1007/s00442-014-2971-1. Epub 2014 May 28.

Reconstructing past ecological networks: the reconfiguration of seed-dispersal interactions after megafaunal extinction.

Author information

1
Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, 11294, São Paulo, SP, 05508-900, Brazil, mathiasmpires@gmail.com.

Abstract

The late Quaternary megafaunal extinction impacted ecological communities worldwide, and affected key ecological processes such as seed dispersal. The traits of several species of large-seeded plants are thought to have evolved in response to interactions with extinct megafauna, but how these extinctions affected the organization of interactions in seed-dispersal systems is poorly understood. Here, we combined ecological and paleontological data and network analyses to investigate how the structure of a species-rich seed-dispersal network could have changed from the Pleistocene to the present and examine the possible consequences of such changes. Our results indicate that the seed-dispersal network was organized into modules across the different time periods but has been reconfigured in different ways over time. The episode of megafaunal extinction and the arrival of humans changed how seed dispersers were distributed among network modules. However, the recent introduction of livestock into the seed-dispersal system partially restored the original network organization by strengthening the modular configuration. Moreover, after megafaunal extinctions, introduced species and some smaller native mammals became key components for the structure of the seed-dispersal network. We hypothesize that such changes in network structure affected both animal and plant assemblages, potentially contributing to the shaping of modern ecological communities. The ongoing extinction of key large vertebrates will lead to a variety of context-dependent rearranged ecological networks, most certainly affecting ecological and evolutionary processes.

PMID:
24865393
DOI:
10.1007/s00442-014-2971-1
[Indexed for MEDLINE]

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