Levels of allozymic diversity in diploid and tetraploid Vaccinium sect. Cyanococcus (blueberries)

Levels of allozymic diversity were examined in native Michigan populations of diploid Vaccinium myrtilloides, and the tetraploids, V. angustifolium and V. corymbosum. Plants from three populations of each species were included in the analysis. Levels of heterozygosity and the number of alleles were averaged over seven polymorphic isozyme loci within both populations and species. As has been found in other studies that compared closely related diploid and tetraploid species, the level of heterozygosity and number of alleles per locus were noticeably lower in the diploid V. myrtilloides (21.7%; 2.9) than in the tetraploids, V. angustifolium (57.1%; 3.4) and V. corymbosum (75.6%; 3.6). The average level of heterozygosity was almost 20% higher in V. corymbosum than V. angustifolium. These two tetraploid species may face distinct selective pressures or have differences in outcrossing rates.