Bi-Directional Sex Change in Coral Reef Fishes from the Family Pseudochromidae: An Experimental Evaluation

Abstract

Coral reef fishes exhibit a diversity of hermaphroditic strategies and comparisons among species with different ecological characteristics will help identify the underlying basis of this complexity. We used manipulative experiments to test the potential for bi-directional sex change in three species of Pseudochromis (Pseudochromidae): P. flavivertex, P. aldabraensis and P. cyanotaenia. The first two species are sexually monochromatic, whereas, P. cyanotaenia is sexually dichromatic. For each species, where two functional females were kept together, one individual in the pair changed sex to male. Where two functional males were kept together, one individual in the pair changed sex to female. In all three species, functional sex change from male to female (52-93 days) took longer than sex change from female to male (18-56 days). In the sexually dichromatic species, P. cyanotaenia, colour change accompanied adult sex change. Females that changed sex to male took on the bright colouration of males and males that changed sex to female took on the drab colouration of females. These results indicate that bi-directional sex change is probably widespread in the family Pseudochromidae and cannot be predicted by the presence or absence of secondary sexual characteristics.