The purpose of this project is to understand how genetic changes contribute to the evolution of new animal signaling behaviors. The investigators of this collaborative project will study this question in weakly electric fishes from Africa, known as mormyrids. The team has previously discovered a protein, encoded by the gene kcna7a that has undergone intense natural selection mormyrids, which allows mormyrids to produce extremely short electric signals called an electric organ discharge (EOD). Despite the strong selection on mormyrids for brief EOD pulses, the evolution of pulse duration varies dramatically across the more than 200 species of mormyrids, and long duration EOD pulses have evolved at least three times from short-duration EOD pulse ancestors. The underlying hypothesis of this project is that the long-duration EODs are the result of selection acting on amino acid substitutions in the kcna7a gene. In this project, the investigators will test this hypothesis by examining the biophysical properties of kcna7a in species that secondarily evolved long duration EODs, and conduct field-based behavioral studies to determine the selective factors that lead to the evolution of long duration EODs. This project will enhance infrastructure for research by adding data products, refined functionality, and tools to the broadly utilized EFISH Genomics Web Portal, promote teaching and learning by ongoing mentorship of undergraduates, graduate students and postdoctoral associates associated and broaden participation by continuing the productive relationship with a network of institutional partners to recruit talented personnel from underrepresented groups, working with Huston-Tillotson University, a HBCU in Austin, TX.
A major goal of 21st century biology is to understand how changes at the molecular level result in phenotypic changes at the organismal level. Despite the growing progress in unraveling the "molecular basis of phenotype" in a wide variety of taxa, it is important to maintain the view that forces at higher levels of biological organization shape phenotypes from the "top down". In many systems, these factors are well known, but their precise connection to identified genetic variants is still poorly understood. In electric fish, the selective forces that influence electric phenotype are known, the loci that produce them are identified, the specific nucleotides within these loci that affect function are characterized, and these loci are known to be targets of selection on macroevolutionary scales. In Specific Aim 1, this project will: determine the biophysical basis of secondary evolution of long EOD pulses by sequencing kcna7a in species that secondarily evolved long duration EODs and their congeners with short duration EODs, measuring their biophysical properties, examining the role of specific sites using site-directed mutagenesis, and determining whether secondarily derived long-duration EODs evolved once or multiple times in parallel. In Specific Aim 2, the investigators will determine whether species that produce long duration EODs have long-duration APs and, and whether properties of kcna7a currents are sufficient to lengthen them, using a combination of electrophysiology and computational modeling. In Specific Aim 3, the investigators will determine the selective factors that lead to the evolution of long duration EODs using by performing field studies in Gabon West-Central Africa. A investigators will continue their efforts to broaden participation of underrepresented groups in partnership with an HBCU.
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.
