Meeting Abstract

S8.10  Tuesday, Jan. 6  Evolution of Cichlid Mating Systems: How Social Behavior Sculpts Brains and Genomes HOFMANN, HA; Univ. of Texas, Austin hans@mail.utexas.edu

Complex brains and behaviors have arisen repeatedly in vertebrate evolution. What adaptive pressures drive such changes? And what are the molecular and physiological mechanisms that underlie these behaviors constraining or facilitating evolution? East African cichlid fishes provide a superb opportunity to analyze the social and ecological correlates of neural phenotypes and their evolution. As a result of rapid, recent, and repeated radiations, there are hundreds of closely-related species available for study, with an astonishing diversity in habitat preferences, social behaviors and brain structures. We use the (monophyletic) Ectodini clade of Lake Tanganyika as our model system, where according to our phylogenetic analyses at least four independent transitions from polygamous to monogamous mating systems have occurred within the past 1.5 million years. I will present ecological, neuroanatomical and genomic results that show how (i) environmental and social factors differentially affect the brain; (ii) arginine vasotocin regulates pairbond formation in cichlids in a way similar to rodents, thus implying a shared mechanism for social affiliation across 400 million years of vertebrate evolution; and (iii) similar as well as novel gene sets have been recruited during these independent transitions towards implementing monogamous phenotypes. These studies provide important insights into the molecular and physiological underpinnings of social behavior and its evolution.