Chromatogram of exon 13 at position 1252 of the Oca2 gene in Refugio Cavefish. A epigeomorphic fish from Refugio Cave have an adenine (green hump), just like surface fish B some hypothesized hybrids that show either a dark caudal spot or a dark retina, and thus are not phenotypically albino albeit being depigmented, were heterozygous, showing a distinct double green and black hump for adenine and guanine C the most troglomorphic fish of Refugio Cave were homozygous for guanine (Black hump), which is in the albino allele reported only for Pachón cavefish among all Sierra de El Abra populations. Fish photos modified from Miranda-Gamboa et al. (2023).