Genetic variation and population structure of Castanea pumila var. ozarkensis

Genetic variation among nine populations of Ozark chinkapin [Castanea pumil a (L.) Mill. var. ozarkensis (Ashe) Tucker], threatened by their susceptibi lity to chestnut blight (Cryphonectria parasitica (Murrill) Barr), was inve stigated. Population genetic parameters estimated from isozyme variation su ggest the populations have a higher genetic diversity (H-e = 0.227) than po pulations of the other Castanea Mill species on the North American continen t, the American chestnut (C. dentata (Marsh.) Borkh.) High levels of hetero zygosity were detected within the populations, but nonsignificant differenc es in genetic diversity were observed among the different populations. Prin cipal component analysis based on isozyme allele frequencies or randomly am plified polymorphic DNA phenotype frequencies showed clustering of the same populations. Populations with high levels of genetic diversity and unusual alleles should be the focal paint of conservation biologists for capturing much of the genetic variation of the species.