Genetic variation in natural populations of the large cranberry, Vaccinium macrocarpon Ait. (Ericaceae)'

1816, the large cranberry has become a regionally important small fruit crop in the United States. In order to assess genetic variation in naturally occurring populations of the large cranberry, sampling was conducted at ten sites distributed from Wisconsin east to Massachusetts, and south to Delaware. Starch gel electrophoresis and substrate-specific staining techniques were used to resolve 23 putative Mendelian loci. Population data collected as individual genotypes were analyzed, generating measures of population structure and genetic diversity. All populations were found to exhibit low levels of genetic variation, e.g., expected heterozygosity (Hexp 0.00 + 0.002-0.057 + 0.030). Relative to other plant species, total genetic diversity was extremely low (H, 0.048) with the majority of all genetic variation due to differences among individuals within populations. This genetic homogeneity was corroborated by Nei's (1978) genetic identity which ranged from 0.977 to one. Recent events in the evolutionary history of this taxon are proposed to have played an important role in determining population genetic structure in this species.