Genetic variability and differentiation of both cultured strains and natural populations in the guppy Poecilia reticulata

To characterize genetically both natural populations and cultured strains o f the guppy (Poecilia reticulata), enzyme polymorphism was examined by star ch gel electrophoresis. There are three kind of natural populations: wild p opulations, natural populations which have originated from the introduction of wild guppy and reversion to the wild state of the domesticated guppy (i ntroduced populations). While the cultured strains have originated from the guppy which have been maintained in pet shops and established as strains. The screening of genetic variation at 30 loci revealed that the introduced populations were significantly higher than the cultured strains in the amou nt of genetic variability. The quantification of genetic differentiation re vealed that the cultured strains were more diversified than the introduced popular ions. The genetic variability of the introduced populations was the similar level in comparison with the wild populations of Trinidadian guppy. The degree o f genetic differentiation of the wild Trinidadian populations was significa ntly more diversified than the introduced populations of the present work. The decrease of genetic variability and increase of genetic differentiation would be caused by founder effect at the division of the population.