Animal behaviors are as diverse as the species that produce them. Behaviors are generated by circuits of interconnected neurons in the nervous system, and behavioral diversity often arises from differences in these circuits. In closely related species that have only recently diverged, the underlying circuits producing distinct behaviors are likely to contain relatively few differences responsible for the observed variation. The goal of this project is to identify functional differences in the brain that contribute to vocal variation between three closely related African clawed frog species. Two general approaches are used: recordings of the electrical signals of individual vocal neurons, and genetic profiling of these neurons. By combining these two complementary approaches, both the functional basis of behavioral differences and the genes responsible for these differences, are being identified. Participation in this project provides students intensive training in physiological, molecular, and computational methods. An inquiry-based research module also is being incorporated in the teaching of the lead investigator, allowing a large number of students from diverse backgrounds to directly engage in neurobiology research. To broaden access to neurobiology training beyond Reed, the lead investigator hosts a laboratory teaching workshop for neuroscience professors around the Pacific northwest. Finally, the lead investigator also convenes a panel of neuroscientists, computer scientists and journalists to develop a new publication platform for efficiently disseminating scientific progress, in which new discoveries can be regularly incorporated into existing "living documents." Together, these efforts aim to accelerate the discovery and dissemination of fundamental principles underlying brain function.
The vertebrate hindbrain includes many neural circuits that generate rhythmic behaviors including vocalizations. Male African clawed frogs produce courtship calls that are unique to each species and differ in temporal patterns. This study investigates neurons that appear to control distinct temporal patterns of vocalizations across three species. Vocal nerve recordings from isolated brains reveal the same pattern of activity that can be recorded in awake, calling frogs. Whole-cell patch-clamp recordings from these 'singing brains' has led to the discovery of premotor neurons that appear to generate the male advertisement call. Because of their apparent importance in the vocal circuit, it is likely that evolutionary changes to these premotor neurons have been important drivers of Xenopus vocal evolution. Whole-cell recordings in the three Xenopus species are used to identify cellular and network properties that correlate with species-specific vocal patterns. To link the physiological bases of behavior differences to their underlying genetic causes, transcriptomes of the premotor nucleus and individual premotor neurons are being generated to identify differentially expressed genes. The studies provide the groundwork for assessing whether certain properties and genes in the vocal circuit are more readily exploited during evolution. Such insights should contribute to novel hypotheses regarding rules and principles of evolution that can be tested across a wide range of species and behaviors.
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.
