Meeting Abstract
Patterning of the dentition varies widely across different vertebrates, typically reflecting adaptations to diet. To begin to understand the developmental and genetic basis of evolved differences in dental patterning, we have been using the threespine stickleback (Gasterosteus aculeatus) system. Ancestral marine sticklebacks have repeatedly evolved major increases in tooth number in derived freshwater populations, likely reflecting shifts in diet to larger prey in freshwater environments. The increases in tooth number in multiple freshwater populations occur late during development, and are associated with an increased tooth replacement rate. We have used genome-wide linkage mapping to identify the genetic basis of evolved differences in tooth patterning. We mapped one genomic region controlling evolved increases in tooth number to an intronic tooth enhancer of the Bone Morphogenetic Protein 6 gene. Ongoing work seeks to further determine the genetic circuitry that regulates tooth patterning, to understand how cis-regulatory changes affect tooth replacement, and to identify specific cell populations involved in tooth formation and replacement. Our genetic studies support the hypothesis that tooth replacement is regulated by homologous genetic circuitry that regulates mammalian hair regeneration, suggesting that an ancient genetic network regulates regeneration of multiple vertebrate epithelial appendages.
