Influence of Hypothyroidism on the Variability of Carotenoid Coloration in Amatitlania nigrofasciata Females (Cichlidae)

The study of the effect of thyroid hormones on the development of the pigment pattern, including the expression of sexual dichromatism, contributes to our understanding of the role of endocrine signaling in the evolution of cichlid fishes, one of the most diverse groups of teleosts. This work shows the effect of reduced thyroid hormone signaling on the development of reversed sexual dichromatism in Amatitlania nigrofasciata , a Neotropical cichlid in which females, unlike males, have carotenoid coloration. In hypothyroid fishes, there was a slowdown in the rate of metamorphic transformations of the pigment pattern and an increase in phenotypic variability. The adult pattern based on carotenoids began to develop in females only after the completion of treatment of thiourea, which suppresses the synthesis of endogenous thyroid hormones. The data obtained indicate a potentially important role of thyroid hormone-mediated developmental plasticity in the diversification of carotenoid coloration in Neotropical cichlids.