Collaborative Research: IntBio: Integrating behavior, neurophysiology,and neural circuit modeling to understand speciation at multiple scales of organization

About This Grant

How can we explain the enormous diversity of life on our planet? For example, there are over 7,000 species of frogs and toads alone. What is the origin of this diversity? Biologists tend to agree that species differ in their basic biology, but how species differences arise is often difficult to study unless one can see catch species just as they form. Social communication in frogs, where individuals produce sounds heard by others, is a key aspect of what makes a species. This project will explore the idea that processes in the brain that influence the choice of mates play a pivotal role in promoting formation of new species (speciation). The work will investigate how neuronal circuits in the brain change in Upland chorus frogs when they encounter other frogs that also produce sounds that are needed for females to choose mates. A primary objective is to better understand what aspects of brain function are particularly prone to change among frog populations and how this divergence promotes the formation of new species. The populations of Upland chorus frogs to be studied are presently undergoing speciation and, therefore, are ideal for this investigation. This project will also train postdoctoral researchers and graduate students to understand brain physiology, animal behavior, and evolution. This project will investigate how ultimate evolutionary forces drive diversification of proximate neural mechanisms of speciation, and how neural divergence, in turn, feeds back to accelerate the engine of speciation. Specifically, the objective is to investigate how the relationship between auditory neural circuits and mating behaviors facilitates reproductive isolation (RI) during speciation. The overarching hypothesis is that divergent selection, acting directly on mating behaviors used in species recognition, can drive differential changes in auditory neuronal circuits, thereby promoting the evolution of RI and the radiation of new species. This project will focus on a species (the Upland chorus frog, Pseudacris feriarum) in which RI has evolved among populations, driven by independent reinforcement of mating behaviors in multiple lineages. Given knowledge of mating behavior and the auditory neurons mediating these behaviors, a series of complementary experiments will characterize the neural architecture of behavioral phenotypes. An empirically informed auditory neural circuit model will be used to generate predictions about the mechanistic neural changes underlying behavioral diversification. These models will then be validated through directed neurophysiological experiments. Finally, integrative modeling will test the evolutionary consequences of this neurodiversity in nature and how this variation contributes to the origin of species. This project is jointly funded by the Evolutionary Processes Program in the Division of Environmental Biology, the Neural Systems Activation Program in the Division of Integrative Organismal Systems, and the Division of Emerging Frontiers, all in the Directorate for Biological Sciences. 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.