Meeting Abstract
As the most species-rich group of vertebrates on the planet, fish consume nearly every possible food type, and therefore must be capable of digesting different foods. Most studies of fish feeding stop with dietary analyses, leaving knowledge gaps about digestion, but it is clear that fishes eating lower-quality foods (i.e. those low in protein and rich in fiber) have larger guts and elevated activities of carbohydrate-degrading enzymes than fishes eating higher-quality foods. The exact genetic underpinnings enabling a fish to “specialize” on a low-quality food remain unknown. The aim of this project is to observe how a fish evolves the ability to make a living on a low-quality diet. Through experimental evolution, we seek to understand how three different diets (high-protein, low-fiber; moderate-protein, moderate-fiber; and low-protein, high-fiber) play a role in the gut size and function of Danio rerio (zebrafish) at the individual level and across generations. Here, we used dissections, digestive enzyme assays, and histological techniques to evaluate the physiological and morphological changes of the digestive tract of the zebrafish in response to the experimental diets in the parental generation. Overall, the activity levels of amylase, lipase, trypsin, aminopeptidase, maltase, and N-acetyl-β-D-glucosaminidase were higher in the guts of the high-fiber diet fish, and the guts of these fish were longer than those in the fish fed the high-protein diets. However, there was a trade-off in fecundity, as the fish eating the high-fiber diet produced fewer offspring than those on the high-protein diets. Thus, zebrafish are clearly able to modulate gut structure and function in the short-term, but the future generations of our experimental lines will allow us to explore what it takes to become a specialist.
