PT - JOURNAL ARTICLE AU - Alan S. Bias AU - Richard D. Squire TI - The Cellular Expression and Genetics of an Established Polymorphism in <em>Poecilia reticulata</em>; “Purple Body, (<em>Pb</em>)” is an Autosomal Dominant Gene AID - 10.1101/121277 DP - 2017 Jan 01 TA - bioRxiv PG - 121277 4099 - http://biorxiv.org/content/early/2017/03/28/121277.short 4100 - http://biorxiv.org/content/early/2017/03/28/121277.full AB - Modification of wild-type carotenoid orange and pteridine red coloration and spotting of male ornaments in both wild populations of Poecilia reticulata (Guppies) and modern Domestic Guppy strains by the Purple Body gene has long been overlooked in research articles and little understood in breeder publications. This modification is commonly found in wild-type Poecilia reticulata reticulata populations from numerous collection sites and has been photographed but not recognized in these collections. It is non-existent or near absent in collections taken from variant populations of Poecilia reticulata wingei. We identify and determine the mode of inheritance, cellular and phenotypic expression by the Purple gene in these stocks. The Purple Body color pigment modification is a distinct polymorphism in wild P. reticulata reticulata populations. Its existence suggests multiple benefits that satisfy female sexual selection preferences, and minimize or reduce potential predation risks. Photographic and microscopic evidence demonstrated that Purple Body is a normal polymorphism in wild and domestic guppies modifying color pigment regions. Purple Body is inherited as an autosomal incompletely dominant trait.