GENETIC ARCHITECTURE IN BUR OAK, QUERCUS-MACROCARPA (FAGACEAE), INFERRED BY MEANS OF SPATIAL AUTOCORRELATION ANALYSIS

Allozyme variation at seven putative polymorphic gene loci (Fle, Idh, Mdh-2, Mdh-3, 6 Pgd-2, Pgi-2, Pgm) was quantified in an isolated Querc us macrocarpa population in northwestern Ontario, Canada. The bur oaks studied were slightly less genetically variable (H(e) = 0.196, A = 3. 43) than the Quercus subg. Lepidobalanus average. To assess the geneti c differentiation within the topodeme, MORAN'S spatial autocorrelation coefficients were used for the nearest-neighbor map and correlograms. Results indicate that most alleles were randomly distributed in space . However, significant genetic patches were detected for two Fle-allel es. Patch width was inferred to be less than 10 m. This spatial substr ucture may be due to limited gene flow and/or demographic factors. Spa tially varying selection can be probably excluded as a spatial evoluti onary force, since site conditions were very homogeneous.