Meeting Abstract
In vertebrates, androgen biosynthesis and signaling through receptor binding are critical regulators of physiological and morphological processes for male-typical reproductive behavior. Muscles essential for courtship behavior and copulation are highly sensitive to androgens, and the amount of androgen available locally within specific tissues may be important for maintaining dimorphic musculature. Lythrypnus dalli, a bidirectionally hermaphroditic fish, exhibits complex and sexually dimorphic reproductive behaviors. For example, males perform courtship displays, characterized by rapid jerky movements towards a female or around the nest, during which the first set of dorsal fins are erect. Dorsal fin movement might be controlled by the supracarinalis muscle that runs the length of the fish between two sets of dorsal fins and the spinal cord. Levels of androgen receptors are higher in males compared to females and are associated with the rates of jerk movements. Here, we found sex differences in the length of the dorsal fin, such that males have longer dorsal fins compared to females. In addition, we measured 11-ketotestosterone (KT), a potent androgen in Teleosts in two regions of the supracarinalis muscle, attached to the first and second set of the dorsal fins. We found that both juveniles with undetermined sex and adult males have higher levels of KT in both regions of the supracarinalis muscle compared to females. In another experiment, we formed social groups that consisted of three females, and induced a social context for protogynous sex change, within which the most dominant female-initiated transition to male behavioral phenotype by establishing her nesting territory and displaying parenting. We will measure KT in the supracarinalis muscles of these fish that have completed 5 d and 10 d towards protogynous sex change.
