Are designer guppies inbred?: Microsatellite variation in five strains of ornamental guppies, Poecilia reticulata, used for behavioral research

Inbred lines are an important tool of genetic studies of all traits, including behavior. Independently derived strains of ornamental "designer" guppies are readily available and predicted to be inbred; however, little is known about actual levels of inbreeding in any of these strains or whether these lines differ in genetic traits that have not been under strong directional artificial selection. We genotyped five designer strains of guppies known to vary in their responses to predator cues and a wild reference population to determine whether designer strains show evidence of inbreeding and whether the strains differed from each other at five microsatellite loci. The designer strains exhibited lower allelic diversity and observed heterozygosity than the wild population. Observed heterozygosity departed significantly from expected heterozygosity for most markers in all five strains of designer guppies. Inbreeding coefficient (f) comparisons between the wild reference population and the designer strains show considerable inbreeding in the designer strains. F-is values for the designer strains also provide evidence of inbreeding. Finally, F-st values indicate that the designer strains differ significantly from each other and the wild population. We therefore concluded that designer guppies are inbred compared to wild populations and differ among strains, making them useful tools for genetic studies of behavioral or life history traits.