Allozymic Variability in Sullivantia (Saxifragaceae)

Populations of Sullivantia species were investigated electrophoreti- cally to evaluate the effect of geographic isolation and small population size on genetic variability. Starch gel electrophoresis demonstrated that Sullivantia species are allozymically depauperate. Only two of ten loci investigated are polymorphic and allozymic variability was detected in only two of 29 populations examined. The paucity of allozymic variability detected for species of Sullivantia is consistent with findings for most other plant species with narrowly restricted distributions. Founder effect and especially genetic drift probably are largely responsible for the very low levels of allozymic variability observed within Sullivantia populations for the two polymorphic enzymes (acid phosphatase and catalase). Because Sullivantia species typically are highly self-fertile, inbreeding probably also has been important in de- termining levels of variability within populations. This investigation also has dem- onstrated that taxa of Sullivantia, which are morphologically distinct and possess distinctive arrays of flavonoid constituents, cannot be distinguished allozymically based on ten loci analyzed.