Meeting Abstract
The evolutionary benefit of mouthbrooding (the incubation of eggs in the mouth) is to increase offspring survival by sequestering the young during development and later releasing them in favorable locations. A prime example of maternal mouthbrooding in fish is the Lake Tanganyikan cichlid, Centrocromis horei. Interestingly, the cichlid itself is parasitized by a brood parasitic catfish, Synodontis multipunctatus. S. multipunctatus breeds exclusively by having the cichlid raise its young. When the cichlid is spawning, the catfish eats some of the eggs and simultaneously release its own gametes. The catfish larvae grow in the cichlid and potentially use the cichlid eggs as food sources. To understand the evolutionary consequences of brood parasitism on the cichlid, we firstly need to characterize this poorly understood ecological interaction. In this study, we documented cichlid mother size in relationship to her offspring clutch size and the rate of brood parasitism in C. horei. We also measured developmental growth rates of both species and their survival rates based on parasitized clutches. Our results showed that the size of female C. horei is positively correlated with the egg type and egg number in her clutch. Over a twenty-month period, 25.7% of C. horei clutches were parasitized by S. multipunctatus. The catfish absorbs its yolk sac by day 5, while it takes 21 days for the cichlid. The strategy appears to be beneficial to the success of S. multipunctatus and detrimental to C. horei. These findings provide a model system to study brood parasitism in controlled laboratory settings, where behavioral, developmental, and evolutionary questions about brood parasitism can be rigorously addressed.
