MICROSATELLITE ANALYSIS OF SEED DISPERSAL AND PARENTAGE OF SAPLINGS IN BUR OAK, QUERCUS-MACROCARPA

Microsatellite analysis was used to examine parentage and spatial dist ributions of 62 adult bur oaks Quercus macrocarpa, and 100 saplings in a single stand. Using genotypes scored by PCR products at four micros atellite loci, we determined that 94 saplings matched at least one par ent in the stand. Saplings often occur as dense clusters of half-sibs around the presumed maternal parent, and only four adults were seed pa rents to a large proportion of the saplings sampled. A stump apparentl y was the seed parent of the largest cluster of half-sibs, which occup ied a sizeable light gap opened up by the death of their maternal tree . Approximately half of the saplings appeared to have grown from seeds that had not been removed after falling from the tree, and half from seeds that were dispersed beyond the crown of their maternal parent. L ong-distance seed dispersal may be more common than has been previousl y reported. Extremely high levels of long-distance pollination were in dicated, and pollen donors within the stand were generally distributed randomly around maternal trees. More than half of the saplings had pa ternal parents outside of the stand. This study demonstrates the utili ty of microsatellite analysis for studying mating systems, seed disper sal and seedling establishment in natural plant populations.