| Description |
Thalassoma bifasciatum, the bluehead wrasse, is a protogynous sequential hermaphrodite and a commonly used model for studying environmental sex determination and adult sexual plasticity. Terminal phase (TP) male bluehead wrasses demonstrate characteristic behaviors and coloration changes when courting the initial phase (IP) females in their population. Upon removal of the TP male, the most dominant IP female will begin to display these male-typical courtship behaviors and coloration changes in a remarkably short amount of time. Despite a vast depth of information surrounding the hormonal changes that occur during behavioral and gonadal transformation, there is a lack of understanding regarding the neural structures that underlie these capabilities. We have used immunohistochemistry experiments to identify the expression of early immediate genes and determined that the interpeduncular nucleus, ventrolateral thalamic nucleus, and the red nucleus are all less active in the brains of IP females performing male-typical courtship behaviors than non-courting IP females. This suggests a decline in inhibitory neural regulation is necessary for IP females to behave as courting males. Additionally, we have identified crucial brain regions behind the onset of courtship coloration by eliciting such changes in immobilized fish through glutamate stimulation of the lateral region of the ventral telencephalon, the dorsal and ventral regions of the ventral telencephalon, the supracommissural ventral telencephalon, and the dorsal habenula. |
