The Mexican tetra, Astyanax mexicanus, comprises 29 populations of cave-adapted fish distributed across a vast karst region in northeastern Mexico. These populations have a complex evolutionary history, having descended from "old" and "young" ancestral surface-dwelling stocks that invaded the region ~8 MYa and ~2.1 MYa, respectively. This study investigates a set of captive, pigmented Astyanax cavefish collected from the Micos cave locality in 1970, in which albinism appeared over the last two decades. We combined...