Overview—Guiding questions, such as why so many species coexist in tropical rainforests, have inspired naturalists for nearly two centuries. I, too, am fascinated by patterns of species diversity, and work in montane gradients to understand how biological communities are structured across habitats and elevations. I integrate different types of data to examine the links between species’ distributions and their thermal ecology, eco-morphology, and evolutionary history. My collaborators and I use phylogenetic comparative methods to test predictions about how species’ life-history traits vary with elevation and habitat use (von May et al. 2018,  PeerJ). We also use these methods to examine divergence in species’ thermal physiology and determine species’ vulnerability to climate warming (von May et al. 2017, Ecology and Evolution). My research also involves taxonomy and systematics of Neotropical amphibians and reptiles, including the description of new species. Though my ongoing studies largely focus on these taxa, I have also conducted research projects focusing on other organisms (e.g., insects; Jacobs, von May, et al. 2018, PeerJ) and ecosystems (e.g., California vernal pools; see below). 

Phylogenetic diversity in tropical elevational gradients—The integration of phylogenetic data with topographic and climatic data has advanced our understanding of montane biodiversity patterns, and recent studies focusing on speciation have recognized that phylogenetically young taxa are often distributed at high elevation. My collaborators and I have assembled a large database containing habitat and life-history trait data for amphibian species distributed along an elevational gradient spanning almost 4,000 m in Manu National Park. This is the protected area with the highest number of species of amphibians and reptiles on the planet. All analyses are conducted in a phylogenetic framework and we are using a multi-locus phylogenetic tree to examine the links among life-history traits, topography, climate, community assembly, and species turnover across elevations. Over the next 10 years, we will establish a wider network of elevational gradients in Peru. This system will be of great interest for students who want to conduct research focusing on ecology, evolution, and conservation of wildlife in diverse landscapes. This research is conducted in collaboration with Alessandro Catenazzi and other colleagues.

Evolutionary radiation of earless frogs—The loss of hearing structures has occurred multiple times in the amphibian tree of life, in diverse habitats and under different selection pressures. In most cases, male earless frogs have retained the ability to call, and species have evolved alternative sensory pathways that enable the transmission of sound to the inner ear. Several genera of terrestrial breeding frogs (Strabomantidae) contain both eared and earless species, and in some clades the large majority of species are earless. In a recent study focusing on terrestrial breeding frogs in the genus Phrynopus, my collaborators and I identified a single evolutionary transition involving the loss of hearing structures that appears to have predated the increase of species diversity in this group. We also observed the absence of advertisement calls, which is highly unusual within frogs, and found that species’ body size and body shape change with elevation (von May et al. 2018,  PeerJ). This research is important because it will help explain what drives regressive phenotypic evolution (i.e., the loss of traits in derived taxa) at high elevations. This research is conducted in collaboration with Molly Womack and other colleagues.

Phylogenetic community structure of lowland amphibians and reptiles—Lowland Amazonian rainforests exhibit high levels of amphibian and reptile diversity, with local communities often housing 80+ species of each group. How do so many species coexist in relatively small areas is a question that has been explored from different angles, but only a handful of studies have used a comparative phylogenetic approach and combined it with multiple species traits and habitat traits. The goal of this study is to examine patterns of amphibian and reptile community structure in lowland Amazonian forests and the role of phylogenetic relatedness on species co-occurrence and abundance across habitats and sites. This study, conducted in collaboration with Dan Rabosky and other colleagues, will be used to test the role of niche divergence and evolutionary history in community assembly.

Conservation status assessments—Amphibians are the most threatened vertebrate group on the planet as a result of species population declines and extinctions. As a member of the International Union for Conservation of Nature's (IUCN) Amphibian Specialist Group, I participate in species' conservation status assessments for the Red List of Threatened Species. The IUCN Red List database is the most comprehensive source of information on globally threatened species (link to news article). Additionally, I am studying the population status and habitat requirements of several threatened amphibian species in collaboration with colleagues from the Amphibian Specialist Group in Peru.

Vernal pool and amphibian ecology—Amphibian breeding and upland habitats are highly susceptible to human disturbance through agricultural conversion and development in the Central Valley, California, where more than 90% of the original vernal pools have been lost. The main goal of this study is to examine how the increased frequency of droughts is affecting the animal community associated with vernal pools in the Eastern San Joaquin Valley. Climatic conditions in this region vary along a north-south axis, with lower annual rainfall, shorter rainy season, and earlier spring warming on the south. In collaboration with other colleagues based in California, I evaluated which abiotic and biotic characteristics are associated with vernal pools occupied by amphibians (California tiger salamander, Western spadefoot, Western toad, Pacific chorus frog) and other aquatic organisms including tadpole shrimp and several species of fairy shrimp (Branchiopoda). This work started in 2010 and includes spring survey data from ~90 pools distributed across five sites.