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| Author(s): |
Mathias Mistretta Pires
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2014-03-10 |
| Examining board members: |
Paulo Roberto Guimaraes Junior;
Marcos Amaku;
Roberto Andre Kraenkel;
Sergio Ivan Perez;
Mauro Galetti Rodrigues
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| Advisor: | Paulo Roberto Guimaraes Junior |
| Abstract | |
The extinction of large terrestrial mammals during the late Pleistocene (between 50 and 11 kyrs ago) is one of the most debated topics in ecology. Most studies on the causes of Pleistocene extinctions focus on the role of external factors such as climate changes and the arrival of humans. Nevertheless, the way an ecological community responds to perturbations depends on its properties, such as its number of species, species composition and the way these species interact. This thesis encloses studies with the final objective of understanding how ecological interactions between Pleistocene large mammals were organized and the potential role of such interactions in the Pleistocene extinction episode. First, I adapted food-web models to reproduce networks depicting different types of ecological interactions between consumers and resources. Then, I used these models to reconstruct predator-prey interaction networks between Pleistocene large mammals and examined the structural and dynamic properties of these systems. Finally, as an overview of the ecological impacts of Pleistocene extinctions, I discuss one of the possible consequences of the demise of Pleistocene large mammals: the loss of seed-dispersal services. The results presented here show that (i) different types of interaction networks between consumers and resources share structural properties and can be reproduced by food-web models; (ii) interactions between Pleistocene large mammals were most likely structured in a similar way to modern large-mammals assemblages in Africa, but the former were especially vulnerable to the changes in structure and dynamics caused by a newly arriving predator such as humans; (iii) among the consequences of Pleistocene extinctions is the reconfiguration of other types of interaction networks such as seed-dispersal networks. Taken together these findings emphasize how important it is to consider the role of ecological interactions in modulating the effects of perturbations when studying extinctions events (AU) | |