HYBRIDIZATION BETWEEN PICEA-RUBENS AND PICEA-MARIANA - DIFFERENCES OBSERVED BETWEEN MONTANE AND COASTAL ISLAND POPULATIONS

Foliage was collected from natural stands of montane and island red sp ruce (Picea rubens Sarg.) and black spruce (Picea mariana (Mill.) BSP) to examine within- and among-population genetic variation. Samples we re scored for frequencies of nuclear ribosomal DNA (rDNA) alleles, and mitochondrial and chloroplast haplotypes. Samples were classified as red spruce, black spruce, or hybrid using two molecular methods: a thr ee character discriminant function based on molecular markers or a thr ee-character molecular index. These results were found to be highly co ngruent with classification based upon a discriminant function using m orphological traits. Among montane populations, hybridization and intr ogression between red and black spruce did not appear to be a major fa ctor in the observed patterns of variation on elevational transects on Mount Washington and Mount Lafayette, N.H. However, extensive hybridi zation and introgression were detected among populations on Isle au Ha ut, Maine. The Mount Lafayette population displayed low variation in r DNA alleles compared with populations on Mount Washington and a range- wide provenance test in Stewartstown, N.H.