Conservação filogenética de interações em redes antagonistas bipartidas

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2017-05-26

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Universidade Federal de Goiás

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This thesis comprises three chapters presented in the form of scientific articles, and approaches phylogenetic conservatism of ecological interactions under different aspects. Citations and bibliographic references are formatted in accordance with the norms from the journal Oikos, where a version of the first chapter was published. Supplementary materials cited in the text can be found in the anexes at the end of the thesis. I begin with the text from my qualification exam, that gives a brief overview about community phylogenetics. By presenting this more general literature, this introduction gives a point of view that complements the specific discussions of each chapter. In the first chapter, my coauthors and I explore the correlation between phylogenetic similarity and the similarity between counterpart sets of plants and herbivores in a regional Asteraceae-flowerhead endophages. By using different measures of counterpart similarity and different subsets defined by herbivore lineages I tried to detect how the evolutionary history of plants and herbivores is reflected in their interactions, both at the specific level as at the modular structure of the network. We show that, beyond the compositional similarity previously reported, closely related species also share a greater proportion of the phylogenetic history of their partners, both for resources and consumers. The comparison between patterns found in the entire network with those found in the subsets provides evidence that resource sharing happens mainly at deeper phylogenetic levels, so that phylogenetic sinal is detectable even among closely related consumers. Asymmetry in signal strength between trophic levels is more evident in the way how network modules reflect host plant phylogeny, both in the entire network and the sub-networks. Taken together, these results show that evolutionary processes, such as phylogenetic conservatism and independent colonization history may be the main forces behind phylogenetic structure observed in this particular plant-herbivore system. In the second chapter, I test with more detail the relative contributions of different ecological processes and the evolutionary history in the formation of the Asteraceae-Tephritidae interaction network. By uniting a previously used approach with a coevolutionary analysis method and some new methods proposed in this work I have shown the striking effect of phylogeny in this system and discuss how the patterns in this antagonistic network differ from other systems. In the third chapter I used a data set compiled from the cophylogeny literature to test the generality of the phylogenetic conservatism observed in other systems. I used a meta-analytical approach to estimate overall effect sizes for the correlations between phylogeny and interactions, as well as the asymmetry in signal strength. I have found a general pattern of phylogenetic conservatism in interaction patterns for both trophic levels along with considerable between-study heterogeneity. On the other hand, the asymmetry in signal strength was consistently small and non-significant in each individual study, with a positive albeit small overall effect size. My results provide compelling evidence that phylogenetic consevatism of ecological interactions is common in nature, togheter with a quantitave picture of its heterogeneity and of the asymmetry between trophic levels. Taken togheter, the results from the three chapters highlight the important role of specialization in structuring antagonistic interactions and the striking presence of phylogenetic constraints in the establishment of this interactions. I hope that the contributions presented here, the questions they raise, and the new approaches I have used help to improve our understanding of the processes that mediate the formation of ecological networks.

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BERGAMINI, L. L. Conservação filogenética de interações em redes antagonistas bipartidas. 2017. 136 f. Tese (Doutorado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2017.