Isoenzyme Identification of Picea glauca, P. sitchensis, and P. lutzii Populations

Electrophoretic techniques were used to identify stands of pure Sitka spruce Picea sitchensis (Bong.) Carr. and pure white spruce P. glauca (Moench) Voss and spruce stands in which introgressive hybridization between the white and Sitka spruce had occurred. Thirteen heteromorphic isoenzymes of LAP, GDH, and TO were the criteria for stand identification. Estimates of likeness or similarity between seed-source areas were made from D determinations. Introgressed hybrid stands had isoenzyme frequencies that were intermediate between the two pure species, but the seedlings were somewhat more like white spruce than like Sitka spruce. Much of the west side of the Kenai Peninsula appeared to be a hybrid swarm area, with stands containing both Sitka and white spruce genes. The presence of white spruce genes in Sitka spruce populations was most easily detected by the presence of TO activity at Rm 52. White spruce showed activity at that position in 79% of its germinants; only 1% of the pure sitka spruce germinants had similar activity. Isoenzyme variation between stands of pure Sitka spruce was less variable than that between interior white spruce stands (mean distinction values were 0.11 for Sitka and 0.32 for white spruce). Cluster analysis showed all six pure Sitka spruce populations to be similar at .93, whereas pure white spruce populations were not similar until .69.