Evolutionary and neurogenomic mechanisms of species discrimination during character displacement

Speciation is a fundamental evolutionary process by which new species form. Behavioral isolation often plays a key role in speciation and occurs when mismatches in mating traits (signals and/or discrimination of those signals) prevent closely related species from interbreeding. The relative importance of changes in signals versus changes in signal discrimination to behavioral isolation remains unknown, as studying cognitive traits such as discrimination has traditionally posed a major challenge in natural populations.

It is now feasible to develop genomic resources and functional genetic tools in non-model systems, providing an exciting opportunity to investigate the neural and genetic basis of behavioral isolation. This project will integrate cutting-edge transcriptomic and genomic approaches to connect patterns of behavioral, neural, and genomic variation within species to large-scale processes of species diversification.

This innovative work will move the field forward by identifying how selection acts on cognitive traits underlying behavioral isolation, providing novel insight into the mechanisms that generate and maintain biodiversity. The broader impacts of this project focus on developing initiatives aimed at supporting underrepresented groups in biology. First, training opportunities and curriculum resources centered on inquiry-based learning will be provided to secondary education teachers from minority serving schools.

Second, curriculum on coding for biology will be designed and implemented through an existing local program for girls interested in gaining experience in coding. Third, students from underrepresented groups will be recruited for paid research positions on this project.

Interspecific reproductive interactions can play a key role in species diversification by favoring the evolution of enhanced behavioral isolation in sympatry relative to allopatry between closely related species, resulting in a pattern of character displacement. Understanding how traits underlying behavioral isolation evolve is central to understanding how species diversify in this manner.

Yet, strikingly little is known about the proximate mechanisms of behavioral isolation, representing a critical gap in our understanding of speciation. This project will test the hypothesis that selection on cognitive traits underlying species discrimination plays a key role in the evolution of behavioral isolation. Well-documented patterns of character displacement in darters, a diverse group of North American stream fishes, will be leveraged in combination with recently developed genomic resources and functional tools in this system.

The mechanistic basis of enhanced behavioral isolation in sympatry will be investigated using three approaches: (1) individuals from sympatric and allopatric populations will be raised in the lab to investigate the genetic and environmental contributions to species discrimination, (2) molecular profiling of behaviorally relevant neurons will uncover the neurogenomic basis of species discrimination, and (3) population genomic analyses in sympatric and allopatric populations will identify the genetic basis of behavioral isolation and speciation. This integrative project will provide unprecedented insight into the mechanistic basis of behavioral isolation.

Furthermore, this project will support the development of educational, training, and mentorship resources for secondary and post-secondary students from groups underrepresented in STEM and for high school biology teachers from minority-serving schools.

This project is jointly funded by the Behavioral Systems Cluster in the Division of Integrative and Organismal Systems, and the Evolutionary Processes program in the Division of Environmental Biology.

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.