Sexual Selection as a Driver of Shared Neural and Reproductive Mechanisms.

Sexual selection theory provides a unifying framework for understanding how cognitive traits, reproductive strategies, and molecular mechanisms coevolve to maximize fitness. Across species, evidence shows that cognitive performance predicts reproductive success through both male-male competition and female mate choice, with individuals displaying superior problem-solving, social dominance, or courtship skills achieving greater mating success. Sexual selection also favors alternative strategies, including sexual mimicry and socially induced sex change, which allow individuals to navigate competitive mating environments and optimize reproductive output. At a mechanistic level, the close evolutionary coupling of cognition and reproduction is reflected in shared cellular, molecular, and genetic architectures between the brain and reproductive tissues, particularly sperm. Conserved genes and pathways involved in signaling, metabolism, epigenetic regulation, and stress responses link neural function to gamete performance across species. We hypothesized that natural selection on cognitive or reproductive traits drives coordinated evolution of shared genetic and molecular pathways between the brain and reproductive tissues, resulting in conserved mechanisms that support both behavioral and fertilization success. To test this hypothesis, we investigated the extent to which the brain and reproductive tissues share conserved genes and molecular pathways, and whether these shared mechanisms provide evidence for coordinated evolution between cognitive and reproductive functions.