Uma perspectiva macroecológica sobre o risco de extinção em mamíferos
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2019-05-23
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Universidade Federal de Goiás
Resumo
The dynamics of diversity on the planet lead to the appearance and disappearance of species
over time. The fossil record currently forms a consistent body of evidence about extinction
events and this phenomenon raises a fundamental question in the study of biodiversity: Why
do some species become extinct and disappear from systems and others not? In this thesis I
took a macroecological approach to achieve the overall goal of elucidating global causes for
mammalian extinction risk. In the first chapter, I partitioned the relative importance of
phylogenetic age, body size and the change of the geographical distribution of species in
determining the risk of global mammal extinction. I accounted for the uncertainty in
estimating predictors in both current and extinct species. I showed that body size is the single
best predictor of extinction risk in mammals, followed by the combined effect of body size and
phylogenetic age. Both the insertion of extinct species and the consideration of the
uncertainty in predictors were important in extinction risk analysis. In the second chapter, I
examined whether landmass size have influenced mammalian extinction risk by restricting the
change in the size of geographic distribution and/or limiting dispersal in search of suitable
habitats for survival. I found that continental physical limits globally influence the extinction
risk of mammals. Continental boundaries prevent mammalian species from following
environments suitable for survival in a context of climate change. I further showed that this
limitation functions as a horizontal spatial constraint for mammalian dispersal. Thus,
mammals that are more limited by landmass size are more likely to become extinct over time
in the course of climate change. In the third chapter, I assessed whether this same restrictive
effect of landmasses on the ability of species to follow suitable environments for survival
influenced the extinction of the Megafauna at the end of the Quaternary. In this context, I
also compared two methods of analysis of the obtained data, the generalized least squares
and the quantile regression. I concluded that the extinction that wiped out much of
Megafauna was a complex, nonlinear event. Megafauna has been limited on its ability to
disperse to new regions where the climate would allow it to survive longer. This limitation was
imposed by the edge of the continents, causing smaller landmasses to lose more species of
megafauna.
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REIS, Vinícius Silva. Uma perspectiva macroecológica sobre o risco de extinção em mamíferos. 2019. 100 f. Tese (Doutorado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2019.