Master's Theses

Date of Award

2017

Document Type

Thesis

Department

Biology

First Advisor

Ana Carolina Carnaval

Second Advisor

Amy Berkov

Third Advisor

David J. Lohman

Keywords

Atlantic Forest, genetic structure, phylogeography, Placosoma, lizards

Abstract

Placosoma is a genus comprised of the Brazilian spectacled lizards P. champsonotus, P. cipoense, P. cordylinum, P. glabellum, and P. limaverdorum. While P. champsonotus, P. cordylinum, and P. glabellum occupy the southern coast of Brazil, P. cipoense is found in the montane grasslands north of that range, and P. limaverdorum was recently discovered in forest isolates that persist within the semi-arid Caatinga. This study elucidates the ecological and evolutionary relationships among these morphologically similar lizards. Using mitochondrial and nuclear gene sequences, genus-wide phylogenies were inferred through Bayesian inference and a species tree approach, and reconciled with geographical and climate data. I generated DNA sequences for the nuclear markers DNAH3, PRLR, and SINCAIP, and the mitochondrial markers ND4 and 16S for all species but P. limaverdorum (for which tissues are unavailable. Results of the phylogenetic analyses were then compared to an environmental Principle Component Analysis of the range of Placosoma to characterize differences in the environments that each species occupies. Each sampled species of Placosoma was recovered as a monophyletic clade, but discordance was observed between the species tree and non-coalescent-based Bayesian trees. In the environmental PCA, P. champsonotus, P. cordylinum, and P. glabellum occupy similar environmental spaces, while the geographically isolated P. cipoense and P. limaverdorum are each similarly isolated in environmental space, albeit along different climatic variables. Both phylogenetic and environmental analyses suggest that P. champsonotus and its sister species P. glabellum may have diverged recently.

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