Sex Differences in Steroid Hormones and Parental Effort across the Breeding Cycle in Amphiprion ocellaris

While it has traditionally been viewed that high androgens are a hindrance to male parental care, recent studies in several vertebrate taxa have shown the opposite pattern, where high androgens either co-occur with, or are necessary for high parental investment. These inconsistencies suggest that in order to develop a complete understanding of the role sex steroids play in parental care, it is important to study multiple species with varying life-history characteristics. Anemonefishes of the genus Amphiprion provide a useful complement to more classically studied systems within vertebrate, and more specifically teleost models of parental care. Therefore, parental behaviors and blood plasma levels of 11-ketotestosterone (11-KT), estradiol (E2), and cortisol were measured in five breeding pairs at three points in the spawning cycle. Males displayed 5.6-fold more parental behaviors and spent 67% of their time in the nest as compared to 12% in females, along with significantly higher levels of 11-KT (males = 0.75±0.076; females = 0.02±0.005 ng/ml). Alternatively, females displayed higher levels of E2 (males = 0.09±0.009; females = 3.65±0.655 ng/ml), and E2 fluctuated across the breeding cycle with low levels on the day eggs were laid and higher levels as eggs developed. Cortisol tended to be higher in males, and higher in breeders than non-breeders, though these differences were not significant (males = 35.8±11.01; females = 16.9±3.58 ng/ml). Results suggest A. ocellaris may be a useful model for studying paternal behavior in the presence of high androgens.