Spatial autocorrelation of allozyme traits in a Norway spruce (Picea abies) population

Using isoenzymes as gene markers and spatial autocorrelation analysis as a tool to detect spatial patterns, we studied the spatial distribution of genotypes in a naturally regenerated uneven-aged Norway spruce (Picea abies (L.) Karst.) stand on the eastern Italian Alps. In most cases we found a random distribution of genotypes in space; in the whole data set less than 11% of genotype pairs showed positive associations for the first (10 m) distance class. Extensive gene flow, due to long distance dispersal of pollen and seeds in P. abies, may account for the observed spatial patterns. A few genotypes (GotB-22, LapB-23, LapB-24, SkdB-12, and MnrB-12) showed a significant clumped distribution over a small spatial scale. We suggested that selection processes driven by environmental variability might have produced significant clumping of these genotypes. However, the role of factors linked to the breeding system, and of chance events, in determining the population spatial structure cannot be excluded in our study.