Anya Theis: The Function of Anal Fin Egg-Spots in Haplochromine Cichlids

PhD-project, Zoological Institute, University of Basel

Colour and pigmentation patterns seem to play a central role in the explosive radiations of cichlid fish species in the East African Great Lakes. Males of the most
species-rich tribe of cichlid fishes, the haplochromines, possess a characteristic pattern on their anal fin, the so-called egg-spots. Some studies assume egg-spots to be a sexually selected trait mediated by female mate preference. However, secondary sexual traits can also be targets of inter- and/or intra-sexual selection. The aim of this study was to uncover the function of egg-spots in the species Astatotilapia burtoni on the levels of inter- and intra-sexual selection.

Could egg-spots have multiple functions in haplochromine cichlids?

These behavioural experiments with A. burtoni show that egg-spots do not serve as sexual advertisement to attract females nor to maximize the fertilization rate, but rather play a role in intrasexual interactions between males. Our results are in contrast to findings of previous studies and suggest that egg-spots have multiple functions in haplochromine cichlids.