CLEMENT, Tricia, S.; GRENS, Kerry, E.; FERNALD, Russell, D.; Stanford University: Reproductive State and Affiliative Behavior in Haplochromis burtoni

We examined behavioral preferences to discover the mechanisms by which social behavior regulates reproduction in the African cichlid, Haplochromis burtoni. Males can be one of two distinct phenotypes, territorial (T) or non-territorial (NT). T males defend a territory, and, compared with NT animals, they are larger, more brightly colored and have fully mature testes (Fernald, 1977). Males exhibit either morph depending on the social context. The transition from NT to T takes about a week while switching from T to NT requires three weeks. During female reproductive cycles, the brain-pituitary-gonadal axis controlling reproduction is remodeled between gravid (egg bearing, G) and non gravid (NG) reproductive states. The control for these changes is internal as opposed to social and occurs about every 28 days (White and Fernald, 1993). Here we asked whether there are measurable behavioral changes corresponding to these physiological benchmarks. To do this, gravid and non-gravid females were given a choice to associate with either T males or NT males, and correspondingly, T and NT males were given the opportunity of associating with gravid or non-gravid females. We found that gravid females preferentially associated with T males, whereas non-gravid females did not. In contrast, both T and NT males affiliated indiscriminately with both types of females (gravid and non-gravid). Thus, affiliation in females does depend on reproductive state whereas in males it does not change with shifted hormonal or perceptual cues. This suggests that in this species, mating success depends on female choice. Furthermore, subsequent experiments examining gravid female preference between T males suggest that they may use a hierarchy of decision cues, preferring T to NT males and, among T males, preferring more active animals.