HELENURM, KAIUS. Department of Biology, University of South Dakota, Vermillion, SD 57069. - High levels of genetic polymorphism in the insular endemic herb Jepsonia malvifolia (Saxifragaceae).
Jepsonia malvifolia (Saxifragaceae) is a long-lived perennial
herb endemic to the Channel Islands of southern California and
Guadalupe Island, Mexico. Twelve populations of J. malvifolia
on San Clemente Island were surveyed for their genotype at 21 allozyme
loci, revealing high levels of genetic polymorphism. For all
individuals across San Clemente Island, 95.2% of loci are polymorphic
with AP = 2.90 and HE = 0.179. Populations
averaged 60.2% polymorphic loci with AP = 2.42 and
HE = 0.158. Most variation is found within rather than
among populations (GST = 0.101) although differentiation
among populations is significant. Genetic identities range from 0.936
to 0.999 with mean I = 0.975. There is no significant relationship
between genetic and geographic distance. Gene flow among populations
is Nm = 9.5 based on private alleles and Nm = 2.2 based on FST.
Outcrossing rates based on fixation indices average t = 0.753,
indicating a primarily outcrossed mating system. The genetic variation
observed is unusually high for an insular endemic herb and indicates
that J. malvifolia is unlikely to be endangered by genetic
factors.
Key words: allozymes, conservation, endemic, genetic variation, Jepsonia, Saxifragaceae