XVI International Botanical Congess

Black spruce (Picea mariana B.S.P. [Mill.]) and red spruce (P. rubens Sarg.) are two conifer species known to hybridize naturally in eastern North America. The hypothesis of a progenitor-derivative relationship between these species was assessed using RAPD and STS (sequence-tagged-site) markers. Trees were sampled from 6 locations in both areas of allopatry and 4 locations from the broad area of sympatry in Quebec. To reduce biases from natural hybridization, parental type individuals were validated a priori using species-specific RAPD markers. Based on 26 STS loci assayed in this study, the unbiased genetic similarity between red spruce and black spruce was high, with a mean value of 0.926. Furthermore, red spruce was genetically depauperate relative to black spruce for all genetic parameters estimated. Allelic variation in red spruce appeared to be a subsample of that observed in black spruce. Implications for speciation mechanisms in conifers will be discussed.