This project will test the hypotheses that mountains have endemic biodiversity in reptile and amphibian fauna because they i) facilitate speciation at a given geographic scale because of topographic and environmental complexity, and ii) provide opportunities for increased population persistence and isolation under climatic fluctuations. This research combines field work in poorly explored highland regions of Brazil, collection data, species distribution models, comparative phylogeography, studies of microhabitat use, and physiological experiments. While generating new and much needed data about a poorly known tropical region and its fauna, this project expands and tests the generality of a process-based method of biodiversity prediction formalized in the PI's postdoctoral work on lowland diversity in Brazil.
This project will inform research priorities and conservation in montane regions of the Brazilian Atlantic forest hotspot and provide important baseline data for assessing responses to future climate change. Education and training opportunities to CUNY undergraduate and graduate students will encourage students from underrepresented groups to participate in this project. Collaborations between US and Brazilian institutions will be strengthened and will lead to new advances in science and conservation in Brazil and the tropics.
Mountains have long fascinated scientists with their tremendous diversity and unique fauna and flora. Why are they so special? Environmental factors known to influence the number of species that a region can hold (such as environmental complexity, area, energy, and humidity) cannot explain why montane regions are so uniquely diverse. To begin answering this question, we combined extensive field work in the mountains of the threatened yet megadiverse Brazilian Atlantic rainforest (Fig. 1), DNA sequencing, and forest modeling to understand the distribution and the genetic diversity of 11 species of montane amphibians and reptiles found nowhere else in the world. Our study organisms included the delicate glass-frogs in the genus Vitreorana (Fig. 2), and the lizards Placosoma, Colobodactylus, Heterodactylus, and Caparaonia. Through field excursions to previously underexplored areas, we inventoried the amphibian and reptile fauna of more than 10 distinct localities and collected specimens of all local species. These field trips discovered four species new to science (two examples in Fig. 3). With the locality data that we gathered, combined with the DNA information collected from field specimens, we were able to solve an important piece of the puzzle of why mountains are so unique: our data indicate that these montane regions have been very stable, from a climatic perspective, over the last 120,000 years (Fig. 4); this allowed the local fauna to persist, and diversity to accumulate, over time. Today, each one of these mountains holds unique genetic lineages that merit research and conservation, as shown by our DNA analyses (an example in Fig. 5). We also documented the prevalence of pathogens that may threaten some of the montane fauna in Brazil. More specifically, we focused our attention on the chytrid fungus Batrachochytrium dendrobatidis, which has been tied to amphibian population declines worldwide. Our findings show that pathogen loads are strikingly different between the montane southern forests (where they are considerably higher) and the mid-elevation forests of the north. These results indicate that the montane forest frogs may be at higher risk of chytrid-related declines, and pinpoints priority regions for research. On a topic particularly important in the face of global warming, we established a protocol to measure how Brazilian montane and lowland species respond to present-day temperature changes. For this, we used three widely distributed groups of lizards and frogs in physiological assays to record their critical maximum and minimum temperatures. By exposing them to increasingly warmer and colder temperatures under controlled conditions, we recorded those at which the animals lost their ability to move. Our results showed that the montane species are able to tolerate more frigid conditions relative to the lowland species, yet both have similar critical maximum temperatures – especially after acclimation. This result, tied to the fact that the temperatures which these organisms are actually exposed to are higher in the lowlands relative to the montane areas, suggest that global warming may affect the lowland taxa more drastically than the montane species. It remains to be seen how warming will affect animal performance in the mountains; we are now expanding our work to address this question. Being conducted at City University of New York (CUNY), one of the nation's largest urban public university, our project provided education and training opportunities to eleven students. Four female undergraduate students (three of them minority) were involved in various aspects of the study, along with three MSc. students (all Latino), three Ph.D. students (one Brazilian), and one postdoc. Working closely with our collaborators, we hosted three Brazilian students in our laboratory (one postdoc, one Ph.D. student, and one Master's Student – each from a different Brazilian university), for three months each. Through collaborative joint field excursions, analyses, and discoveries, this one-year project resulted in 10 collaborative publications and 22 contributions to international scientific meetings that were co-authored by the many US- and Brazil-based members of our growing research group. The project tremendously strengthened the international linkages and collaborations between CUNY and South American students, and established a strong foundation for ongoing studies in our groups. Moreover, the genetic data from one group of lizards were used to create a hands-on module to teach molecular evolution to CUNY undergraduates – expanding the benefits of our work within the College. This module was implemented as part of a Biotechnology course offered in 2012 to upper-level seniors and Master’s students. Broadening the impacts of our study in Brazil, we used our field work as a channel for communication with local communities, and worked closely with park rangers and managers of the many biological stations we visited, as well as private land owners. As a result of these ties, we are now establishing climate monitoring stations in private residences in several montane areas visited by our group, with the goal of tracking local populations and their environments over longer periods of time.
