Same, same, or different? Mechanisms of Parental Care Between Sexes

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Sex differences are a common feature of animal behavior. Yet, the mechanisms underlying these behavioral differences have proven difficult to understand because brains and genes are nearly identical between males and females, and behavior typical of one sex may occasionally be performed by the opposite sex. The goal of this project is to understand how hormones, neural activity, and gene expression interact to give rise to sex differences and reversals in behavior. Parental behavioral is a promising starting point, as many species exhibit sex differences in parental care, as well as the potential for sex-reversed care. The project capitalized on naturally occurring parental flexibility in a Neotropical poison frog, Dendrobates tinctorius. Males are the primary care givers in this system, with females only occasionally taking over, providing an important complement to existing work in mammals where parental care is female biased and limited by reliance on lactation. Outcomes of the project will provide new understanding of how behavioral sex differences are coded in the brain, how these differences lead to distinct behavioral patterns, and the conditions under which they can be altered or reversed. The project will train researchers at all stages, with a focus on recruitment of trainees from groups underrepresented in STEM. Additionally, poison frogs are fascinating, charismatic creatures that facilitate teaching of diverse audiences, including K-12 students and teachers through the “Froggers School Program” and the general public through community engagement events. A fundamental question at the intersection of evolution, behavior, and neurobiology is how novel behaviors arise and are incorporated into existing neural systems. Cross-sexual transfer, the emergence of traits initially exhibited only in one sex in the opposite sex, has been proposed as a major, underappreciated force in the evolution of behavior. Yet, the mechanisms that facilitate integration into opposite sex physiological, neural, and molecular systems are largely unknown. Solving this puzzle is intimately tied to understanding how behavior is coded across levels of organization – from genes, to gene networks, to cell types, to neural circuits, to physiology, to behavior. Leveraging naturally occurring parental care in Dendrobates tinctorius poison frogs, this project tests the central hypothesis that mechanistic interactions across levels of organization shape behavioral flexibility and evolution between sexes. Specifically, the project links hormone and neural activity patterns to individual variation and sex differences in behavior, asks whether shared versus distinct genes and cell types are associated with parental care in males and females, and causally tests these hypotheses by tracing the effects of hormone manipulations across levels of organization. Synthesis of data across multiple levels of organization is a key feature of this work. Additionally, the project will contribute to training of diverse researchers and community engagement. Project outcomes will provide inroads to understanding how behavioral sex differences are coded in the brain, the conditions under which they can be altered or reversed, and how underlying mechanisms are environmentally, developmentally, and evolutionarily tuned to coordinate complex behavior.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.