Joshua B Gross

Biography

The evolution of phenotypic differences between even closely-related organisms involves a complex set of genetic changes. These changes are frequently manifested as the altered expression, or structure, of gene products. To understand the genetic changes that accompany adaptation to extreme environments, we utilize a model system called the blind Mexican cavefish (Astyanax mexicanus). This species harbors two distinct morphotypes, a blind and depigmented cave-dwelling form and a surface-dwelling form. The surface-dwelling form resembles a typical aquarium fish with normal pigmentation and well-developed eyes. In contrast, the cave-dwelling form has no eyes whatsoever and is completely devoid of pigmentation. In addition to the traits that have been lost, cave forms have evolved a significant number of constructive changes. These phenotypes, such as an expanded sense of taste and an amplified lateral line system, facilitate food-finding ability in the complete darkness of a cave. We utilize a variety of approaches including quantitative genetics, transcriptomics, activity analysis and high-resolution phenotypic studies of both cave and surface forms. Along with an extensive historical literature characterizing these remarkable animals, our integrative approaches enable us to better understand the genetic changes accompanying colonization of a novel and extreme environment.

Research Interest

ECBR, SBBE, Evolution and development of vertebrates; Evolutionary genetics of natural populations; Cave biology; Genetic basis for phenotypic changes; Mexican cave tetra, Astyanax mexicanus