A genome-wide association study for the red-eyed trait (ocular albinism) in an F2 population of guppy (Poecilia reticulata).

Guppy (Poecilia reticulata) is a popular tropical ornamental fish with high phenotypic diversity. This study investigates the genetic basis of the red-eyed trait (ocular albinism) in guppy through hybridization between the sky-blue strain (red-eyed) and the red-fun strain (black-eyed). Our results demonstrated black eye to be the dominant trait relative to red eye, and that the ratio of the number of black-eyed guppies to that of red-eyed ones in the F2 generation is consistent with 3:1, which indicates that the red-eyed trait in the sky-blue strain guppies conforms to the model of Mendelian monogenic inheritance. To identify candidate genes associated with the red-eyed trait in guppies, we conducted a genome-wide association study using 65 F2 individuals (23 red-eyed and 42 black-eyed). A total of 106 genes showed significant associations with the red-eyed trait in guppy and OCA2 was considered as the most important candidate gene. This study provides a reference for insights into the molecular mechanisms underlying ocular albinism in guppy.