Evolution of the Mexican cavefish gut microbiome

In this study, we use the Mexican tetra, Astyanax mexicanus, to investigate how rapidly evolution can shape host-driven intestinal microbiome composition. A. mexicanus is a species of fish consisting of river-dwelling surface fish and multiple eyeless cave-dwelling cavefish that diverged from surface fish less than 200 thousand years ago. Surface fish and cavefish have been bred in laboratories for generations to study the genetic and developmental basis of cavefish traits like eye and pigment loss6, reduced aggression, adiposity, and insulin resistance. We used 16S rRNA sequencing to compare the intestinal microbiome of surface fish and cavefish that were collected in the wild, to the same populations of fish that were raised from embryos under identical conditions in the lab.