Master's Theses

Date of Award

2014

Document Type

Thesis

First Advisor

Ana Carolina Carnaval

Second Advisor

Michael J. Hickerson

Third Advisor

Robert P. Anderson

Keywords

Brazilian Atlantic Rainforest, climatic refugia, climatic stability, glassfrogs, molecular evolution, phylogeography, species distribution modeling, landscape genetics, Vitreorana

Abstract

The Brazilian Atlantic Forest harbors one of the most diverse faunas of the world, including 2-3% of all known vertebrate species. Understanding the role of both climate and landscape in shaping current biodiversity patterns has been the focus of many recent phylogeographic studies. Here I explore multiple factors thought to have impacted the generation of local diversity in the Brazilian Atlantic Forest (AF) using two montane, stream-associated species of glassfrogs – V. eurygnatha and V. uranoscopa. I integrate species distribution modeling, path analysis, and molecular data to test the role of climatic stability, rivers, mountain chains, and geographic distance in shaping genetic differentiation. Moreover, I test the affect of climatic stability on the maintenance and spatial distribution of diversity and test for signatures of demographic change. My molecular data suggest cryptic speciation and the possibility of a third Vitreorana species inhabiting the AF. Intraspecific phylogenies indicate significant regional structure in both species, with a phylogeographical break in São Paulo State that matches breaks found in several other AF taxa. Contrary to previous studies of lowland taxa, models of reconstructed paleodistributions reveal that these montane species were likely able to persist in the southern AF during glacial periods, particularly during the LGM. Molecular data failed to detect signatures of population expansion or evidence of a latitudinal diversity gradient in these species. Lastly, results highlight the importance of testing the impacts of multiple mechanisms underpinning diversity patterns in this region.

 
 

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