A Novel Genetic Model of Dietary Response and Host-Microbiota Interactions
North Carolina State University
Maladaptive diets are the leading contributor to morbidity and mortality worldwide. Disease outcomes stemming from both undernourishment and overconsumption represent evolutionary discordance: the human genome has been unable to evolve to match rapid dietary changes brought on by overpopulation and the agricultural and industrial revolutions. If we reveal pathways of genetic evolution taken by other vertebrates as they adapted to diverse diets, we should identify pathways for therapeutic intervention for pathological conflicts in humans brought on by maladaptive diets. East African cichlid fish species have recently evolved diverse dietary adaptations, providing powerful comparative experimental strategies to understand the genetic basis of dietary response. We are using genomic and developmental biology techniques to identify species-specific aspects of gastrointestinal morphology and function within three focal species representing three trophic levels (Labeotropheus, herbivore; Metriaclima, omnivore; and Aulonocara, carnivore). Gut length correlates with trophic level, but functional compartmentalization within the gut does not scale directly with length. Transcriptional patterns in the cichlid gut are similar to those in human gut, demonstrating a shared genetic toolkit for gut development. Gut microbiota is relatively labile and varies with species, diet, age, and gut region; however, host species-specific differences are identifiable and suggest host genetics plays a strong role in bacterial colonization of the gut. Functional profiles of bacterial assemblages also diverge by host species, with bacteria providing biochemical processes that correlate to the adaptive diet of each species. Our findings to date provide comparative insight into dietary adaptation, and lay an essential foundation for genetic mapping experiments in hybrid crosses and natural populations.