Meeting Abstract

69.2  Sunday, Jan. 6  Patterning the diverse dentitions of Lake Malawi cichlids FRASER, G. J.**; STREELMAN, J. T.*; Georgia Institute of Technology, Atlanta; Georgia Institute of Technology, Atlanta gareth.fraser@biology.gatech.edu

Cichlid fishes of Lake Malawi offer a unique glimpse of rapid adaptive evolution, with hundreds of species evolving from a common ancestor in the last 500,000 years. Despite genetic similarity, cichlid craniofacial diversity is dramatic. For instance, piscivores and plankton eaters have one to two rows of widely spaced unicuspid teeth on their oral jaws, while algivores have up to fifteen rows packed with hundreds of tricuspids. Our goal is to understand the evolutionary development of diversity in the cichlid dentition. Here we describe the expression of multiple genes during tooth development in three closely related cichlid species with divergent dentitions. We show that gene expression patterns prior to morphogenesis of the first teeth exhibit marked contrasts between species, reflecting the future distribution of functional teeth of specific shape and order. We provide evidence that key developmental genes, essential to the toolkit for vertebrate development, can be tweaked on a small-scale to define evolutionary novelty. Our data suggest a general molecular mechanism for the organization and patterning of a complex multi- rowed vertebrate dentition.