Genetic variability and founder effect in the pitcher plant Sarracenia purpurea L

The organization of genetic variability in the pitcher plant, Sarracenia purpurea L., was examined. Particular attention was given to the Cranberry Island population which was founded by a single specimen in 1912. Ten additional populations were also sampled for genetic variability at ten genetic loci. S. purpurea has a moderate level of genetic variability; half of the loci are polymorphic and heterozygosity per individual is 9.5%. Genetic diversity in the species was apportioned into within and between population components. The within population component is .67, indicating a substantial portion of the genetic diversity in the species is not represented within individual populations. Analysis of allele frequencies by chi-square and F statistics also indicate substantial levels of differentiation between populations. Gene frequencies and identity values show no correlation with geographical distance; however, heterozygosity and mean number of alleles per locus are significantly higher in the eastern populations. The Cranberry Island population exhibits reduced genetic variability relative to the species as a whole. Only one polymorphic locus was found, and heterozygosity per individual is 50% below the species mean. However, several other populations also exhibit low levels of genetic variability relative to the species. Founder effect and genetic drift may account as well for the loss of variability in these isolated populations.