Cave fishes differ from surface fishes in numerous ways because of their evolutionary adaptations to life in the dark. Most noticeably, they have smaller eyes and less pigmentation, but they also have better senses of smell and taste, and are more efficient metabolically. All of these differences are under genetic control; the gene copies in the cave populations affecting important developmental systems differ from those in the surface populations. The Mexican Tetra is unique in that the species has both cave and surface forms. Because they can hybridize, they afford the opportunity to investigate the differences through genetic analysis. In this collaborative research project, the genes responsible for these differences will be identified by genetic mapping and functional analyses of selected candidate genes. The results will lead to a better understanding of the genetic pathways that control the development and maintenance of: (1) the visual system; (2) pigmentation; (3) metabolic efficiency; and (4) various other physiological and anatomical systems. In terms of Broader Impacts, the work on cave fishes has been well covered by the media, and the extraordinary ability of this system to engage people's interest and attention will have broad positive impacts on public education in biology, genetics and evolution. The research will also impact the training of undergraduate and graduate students and postdoctoral fellows, particularly in novel concepts of evolution and development (evodevo). In terms of societal impacts, the results may also contribute to a general understanding of the causes of eye degeneration and metabolic disorders and could lead to a better insight into how environmental changes (i.e., the shift from surface to cave environments) can modulate the direction of evolutionary change.
