HERMAN, SALLIE J.* and LINDA A. RAUBESON. Central Washington University, Department of Biological Sciences, Ellensburg, WA 98926. - Genetic Diversity of a Rare Buttercup.
Ranunculus triternatusoccurs as a few isolated populations in
Washington, Oregon, Idaho, and Nevada. We have used RAPD (randomly
amplified polymorphic DNA) polymorphisms to measure genetic diversity
among 25 individuals from one population from Columbia Hills Preserve
near Goldendale, WA. For comparison, we have also examined 25
individuals from a population of the widespread sagebrush buttercup,
Ranunculus glaberrimus. Using ten different 10-mer primers with
the 50 DNAs, we generated a total of 87 different RAPD bands.
Thirty-two bands were common to the two species; whereas 37 were
unique to R. triternatusand 17 were unique to R.
glaberrimus. The rare species,R. triternatus, has a higher
number of variable loci (62% polymorphism versus 22% for R.
glaberrimus), a higher proportion of genetically distinct
individuals (100% R. triternatus vs. 88% for R.
glaberrimus), and a greater average genetic distance among
individuals (0.19 for R.triternatusvs. 0.06 for R.
glaberrimus). Thus, this rare species, considered a species of
concern in Washington State, does not seem to be suffering from
reduced genetic diversity as compared to the widespread species. In
addition to showing a higher level of genetic diversity among members
of the rare species, the RAPD data also support the separateness of
the two species. As only one population of each species has been
tested, this last contention will need to be further investigated by
examining samples from additional populations of each species. This
further sampling is currently underway.
Key words: genetic diversity, Ranunculus triternatus , RAPDs