BRC-BIO: Phenotypic convergence and trait loss in high-elevation Andean frogs

California State University Channel Islands, Camarillo CA

Investigators

Abstract

Tropical mountains are natural laboratories to study how the environment generates and shapes organismal diversity. In the high Andes, cold temperatures and unique habitats play an important role in the distribution, activity, and behavior of organisms. Interestingly, these conditions support a diverse group of amphibians known as terrestrial-breeding frogs. Recent work on these frogs has revealed that distantly-related species living at high elevations exhibit more similar body shape to one another (e.g., they have shorter limbs and shorter snout) than species at lower elevations. Additionally, high-elevation frogs often lack ears compared to those found at lower elevations. This project will identify factors that explain these predictable body forms. It will also explore how lacking ears may affect the social communication of high-elevation Andean frogs. Through collaborations across universities and natural history museums, the project team will obtain X-ray images and measure the skeleton and other internal structures in preserved specimens. The team will use genetic data to determine the species’ evolutionary relationships and identify patterns of repeated evolution among similar features. This project will provide practical and engaging research experiences for undergraduate students. Additionally, high school students will participate in a workshop providing information about education and research opportunities at the university. Through these experiences, the project will advance the goal of increasing participation of underrepresented groups in Science, Technology, Engineering, and Mathematics. Convergent evolution is the emergence of similar phenotypic traits in distantly-related species. It is a common feature of many evolutionary radiations. Classic examples of adaptive radiations on islands (e.g., Anolis lizards) reveal that predictable phenotypes can evolve across biogeographic space. These patterns provide insights into the role of the environment in shaping morphological, physiological, and behavioral traits. However, understanding how different morphological traits evolve in replicate evolutionary radiations remains challenging because traits can vary independently (e.g., skull shape and limb length in frogs can exhibit different rates of morphological change). Additionally, the loss of some traits can lead to changes in other linked or unlinked traits. This project aims to use new data on morphological diversity, phylogenetic relationships, and elevational distribution of terrestrial breeding frogs (Strabomantidae) to understand patterns of phenotypic convergence and trait loss at high elevations. Research will focus on eight genera (Bryophryne, Lynchius, Noblella, Microkayla, Oreobates, Phrynopus, Pristimantis, and Psychrophrynella), containing species living in high-elevation Andean habitats. Morphological data collected using X-ray micro-computed tomography (microCT scanning) will be combined with ecological and phylogenetic data. The data will be used to test if similar high-elevation environments lead to similar body shapes. Additionally, this research will examine whether independent losses of key structures in acoustic communication have been lost or modified at high elevation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.