The Role of Sex Steroid Hormones During Reproductive Maturation in a Highly Social Fish Species
Campus Only Senior Thesis
Bachelor of Arts
© 2022 Emma Thompson
Puberty is a developmental period in which an individual becomes sexually mature. While the sequence of pubertal changes is relatively well understood, the timing and pattern of these changes are largely unknown for many animals. Hormonal regulation and activation, gene expression, and social environment are speculated to impact individual variation during puberty. In this study, the sex steroid hormone levels from adolescent African cichlid fish, Astatotilapi burtoni, were used to investigate developmental trajectories. A. burtoni are used due to the quick nature in which they mature, and the critical role sex steroid hormones play in adult social behavior, morphology, and growth. A. burtoni, form social hierarchies that include three different phenotypes: dominant males, subordinate males, and females. The social status phenotypes are highly plastic as dominant and subordinate males switch phenotypes. The sex steroid hormones, testosterone, and estrogen were measured in juveniles along with body size and growth. Testosterone and estrogen concentrations, along with proxy calculations of the conversion rate of testosterone to estrogen were analyzed in relation to growth and to developing phenotypes of the fish. We successfully measured growth in all experimental fish and found variation in and between different communities. We found that hormones play a role in the regulation of growth in the latter half of puberty in juveniles. Fish that began to develop in dominant males demonstrated higher concentrations of testosterone, estrogen, and a higher rate of testosterone-to-estrogen conversion. Through this study, we will gain insight into hormonal regulation of growth, sex determinism, and social hierarchy emergence during sexual maturation in A. burtoni. Overall, we aim to better understand what role sex steroid hormones have during puberty and how individuals uniquely develop.
Thompson, Emma, "The Role of Sex Steroid Hormones During Reproductive Maturation in a Highly Social Fish Species" (2022). Scripps Senior Theses. 1996.
Available for download on Monday, December 09, 2024
This thesis is restricted to the Claremont Colleges current faculty, students, and staff.