Overview

Amphibians are a conspicuous and ecologically important component of the world’s vertebrate fauna, with more than 7,000 species worldwide and more than 1,000 species in Brazil. They are also a highly endangered group whose current rate of extinction is hundreds or thousands of times greater than the background extinction rate. Our research seeks to discover and describe amphibian diversity and the evolutionary events and processes that explain it. Specifically, we are mainly pursuing three interrelated lines of research.


Our research is generously supported by





Computer Hope

Amphibian systematics

The general objective of our research in amphibian systematics is to understand the phylogenetic diversification of amphibians and how it relates to the evolution of particular character systems, including morphological, molecular, and behavioral evolution. Using evidence from DNA sequences and adult and larval morphology and behavior, we are studying several groups of amphibians, with emphasis on Neotropical clades.


Computer Hope

Amphibian chemical defense

Amphibians are characterized by their naked, highly permeable skin that provides meager mechanical protection against the predators, parasites, and pathogens that thrive in the moist environments they inhabit. However, all amphibians are protected by an exocrine defense system composed of cutaneous poison glands—specialized cells that secrete a variety of defensive chemicals, defined as substances that are produced in order to reduce the risk of bodily harm by another organism. These secretions are believed to function as an important component of the innate immune system in defending against pathogens and parasites and are also involved in complex antipredator mechanisms. Our studies focus primarily on the evolution and ecology of chemical defense in poison frogs of the families Bufonidae (Melanophryniscus) and Dendrobatidae (independently derived in Epipedobates, Ameerega, and Dendrobatinae), which do not biosynthesize their chemical defenses but instead sequester lipophilic alkaloids from their diet (primarily from mites and ants).


Computer Hope

Invasion biology of the American bullfrog

The American bullfrog, Lithobates catesbeianus, is originally from eastern North America and was brought to Brazil in the 1930s to be cultured for human consumption. Bullfrog farming has great potential as a profitable business that could positively impact the lives of many Brazilians in rural areas and might have a smaller ecological footprint than other agricultural practices like cattle ranching and sugar cane farming. However, the bullfrog is also one of the world's 100 worst invasive species and has the potential to cause major, irreversible, negative impacts on native biodiversity, especially amphibians. Invasive populations occur across much of the Atlantic Forest, especially in southern Brazil, and it is known that both bullfrog production and the distribution of feral populations are expanding. Little is known about the process of this biological invasion and, most importantly, the responses of native fauna. Our research employs comparative and experimental approaches to increase understanding of the process of bullfrog expansion and the responses of native amphibians to invasive bullfrogs. This information is immediately useful to ecosystem managers and policy makers and also provides evolutionary and ecological insights for invasion biology.