Meeting Abstract
Cichlid fishes of the East African rift lakes are well known for their explosive speciation and dramatic phenotypic diversity. These radiations are characterized by a wide array of extreme trophic specializations. While the craniofacial modifications associated with dietary specialization have received significant attention, associated differences in gut morphology are not well understood. Understanding the morphological, developmental, and genetic changes correlated with dietary shifts will not only allow us to better understand how trophic diversity evolved in cichlids, but also broader patterns of vertebrate trophic specialization, and the interaction between diverse human gut phenotypes, dietary adaptation, and diet-related disease. Unlike tetrapods, gut regionalization in teleosts is often not easily visualized. The cichlid gut is a simple tapered tube, with no obvious distinction between small and large intestine. Using phylogenetically robust molecular markers of these regions, we have determined that both overall gut length, and the relative percentages of the adult gut expressing large and small intestinal markers follow broad vertebrate trends correlating gut morphology and dietary specialization. Additionally, we have characterized the emergence of these species-specific phenotypes through ontogeny from a generalized larval state. A separate large and small intestine have not previously been identified in cichlids, and our data are the first description of cichlid gut morphology from fishes raised in a common garden, demonstrating that identified differences are not the result of a plastic response to diet, but instead are heritable and species-specific.
