Mapping the Genetic Basis of Troglomorphy in Astyanax: How Far We Have Come and Where Do We Go from Here?

The distinct phenotypes of the cave forms of Astyanax mexicanus from the surface forms are captivating (e.g., lack of pigmentation, eye-degeneration, and metabolic and behavioral divergences from SF). These phenotypes are especially interesting because they are amenable to genetic dissection through classic quantitative genetic crosses and quantitative trait locus (QTL) due to the availability of an interfertile close relative with more "normal" phenotypes. Such methods are simply statistical associations between genotypes and phenotypes, and the cavefish (CF) community has been extremely successful in conducting these studies and identifying regions of the genome associated with cave phenotypes. Here we review past studies that sought to identify the genetic bases of CF traits through QTL mapping and discuss ways to integrate past knowledge and work with future technologies and analytical methods.