COMPLETE CONGRUENCE BETWEEN GENE DIVERSITY ESTIMATES DERIVED FROM GENOTYPIC DATA AT ENZYME AND RANDOM AMPLIFIED POLYMORPHIC DNA LOCI IN BLACK SPRUCE

Controversy still exists over the adaptive nature of variation of enzy me loci. In conifers, random amplified polymorphic DNAs (RAPDs) repres ent a class of marker loci that is unlikely to fall within or be stron gly linked to coding DNA. We have compared the genetic diversity in na tural populations of black spruce [Picea mariana (Mill.) B.S.P.] using genotypic data at allozyme loci and RAPD loci as well as phenotypic d ata from inferred RAPD fingerprints. The genotypic data for both alloz ymes and RAPDs were obtained from at least six haploid megagametophyte s for each of 75 sexually mature individuals distributed in five popul ations, Heterozygosities and population fixation indices were in compl ete agreement between allozyme loci and RAPD loci, In black spruce, it is more likely that the similar levels of variation detected at both enzyme and RAPD loci are due to such evolutionary forces as migration and the mating system, rather than to balancing selection and overdomi nance. Furthermore, we show that biased estimates of expected heterozy gosity and among-population differentiation are obtained when using al lele frequencies derived from dominant RAPD phenotypes.