Mechanisms and evolution of sexually dimorphic electrocommunication signals

Indiana University, Bloomington IN

Investigators

Abstract

Sexually dimorphic communication signals evolve rapidly and are among the most widespread, diverse, and conspicuous behaviors that animals produce. This project will combine evolutionary and physiological approaches to study how sexual differentiation of the brain evolves in relation to sex differences in behavior. The project will address this question by comparatively studying mechanisms that regulate sexual dimorphic signals in a species-rich family of South American electric fish. These animals generate weak electrical signals to communicate information about species, sex, social rank, and motivation. The magnitude and direction of sex differences in electric communication signals vary across species. Sex differences in these signals are regulated by hormones like testosterone and estrogens and by neuromodulators like serotonin. The brain circuit that controls electric communication signals is well-characterized and relatively simple. These features facilitate investigations of how hormone-brain-behavior interactions evolved to produce species diversity in sexual dimorphic behavior. The project has four goals: (1) to compare sex differences in signals across species and investigate the coevolution of sex differences in different signal components; (2) to determine whether species diversity in sexual dimorphic behavior evolves through changes in the hormonal sensitivity of behavior; (3) to determine whether sex differences in behavior evolve through changes in neuromodulation in brain regions that control communication signals; and (4) to determine whether sex differences in behavior evolve through changes in the intrinsic physiology of brain cells. Undergraduates will help collect and analyze data and will be trained and encouraged to pursue scientific careers. The project will maintain a robust international collaboration between Indiana University and the National Institute of Amazon Research in Brazil. The project will generate recordings of electric communication signals that will be deposited in a public database and provide resources for research and teaching on animal communication, sex differences, biodiversity, sensory biology, and biophysics.