title: Social regulation of male reproductive plasticity in an African cichlid fish.
abstract: Social interactions with the outcome of a position in a dominance hierarchy can have profound effects on reproductive behavior and physiology, requiring animals to integrate environmental information with their internal physiological state; but how is salient information from the animal's dynamic social environment transformed into adaptive behavioral, physiological, and molecular-level changes? The African cichlid fish, Astatotilapia burtoni, is ideally suited to understand socially controlled reproductive plasticity because activity of the male reproductive (brain-pituitary-gonad) axis is tightly linked to social status. Males form hierarchies in which a small percentage of brightly colored dominant individuals have an active reproductive axis, defend territories, and spawn with females, while the remaining males are subordinate, drably colored, do not hold a territory, and have a suppressed reproductive system with minimal opportunities for spawning. These social phenotypes are plastic and quickly reversible, meaning that individual males may switch between dominant and subordinate status multiple times within a lifetime. Here, we review the rapid and remarkable plasticity that occurs along the entire reproductive axis when males rise in social rank, a transition that has important implications for the operational sex ratio of the population. When males rise in rank, transformations occur in the brain, pituitary, circulation, and testes over short time-scales (minutes to days). Changes are evident in overt behavior, as well as modifications at the physiological, cellular, and molecular levels that regulate reproductive capacity. Widespread changes triggered by a switch in rank highlight the significance of external social information in shaping internal physiology and reproductive competence.
authors.affiliation: *Department of Biology, Stanford University, Stanford, CA 94305, USA; Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: Karen P
authors.initials: KP
authors.lastname: Maruska
authors.forename: Russell D
authors.initials: RD
authors.lastname: Fernald
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D000818:Animals; D023681:Cichlids / Q000502:physiology*; D012739:Gonadal Steroid Hormones / Q000378:metabolism; D006062:Gonadotropins / Q000378:metabolism; D006066:Gonads / Q000378:metabolism / Q000502:physiology; D006608:Hierarchy, Social; D008297:Male; D012098:Reproduction / Q000502:physiology*; D019849:Sex Determination Processes / Q000502:physiology; D012744:Sex Ratio; D012726:Sexual Behavior, Animal / Q000502:physiology*; D012931:Social Environment
chemical_list: D012739:Gonadal Steroid Hormones; D006062:Gonadotropins