COMPARISON OF POLLINATOR FLIGHT MOVEMENTS AND GENE DISPERSAL PATTERNSIN MIMULUS RINGENS

Pollinator movements and pollen-mediated gene dispersal were quantifie d in experimental populations of square-stemmed monkeyflower (Mimulus ringens), a wetland perennial herb with a mixed-mating system. Each po pulation consisted of genets with unique multilocus combinations of ho mozygous genotypes, facilitating assignment of paternity to all sample d seeds. Replicate arrays were planted at each of three spacings spann ing the range of densities typically observed in natural M. ringens po pulations. In all six arrays the distribution of gene dispersal distan ces differed significantly from the distribution of pollinator flight movements. The mean gene dispersal distance was 1.46 times as far as t he mean pollinator flight distance. These differences were probably ca used by pollen carryover as bumblebees visited up to 12 M. ringens pla nts on a single foraging trip. Although gene movements exceeded pollin ator flight distances, estimates of neighbourhood size were consistent ly low, ranging from 1.66 to 5.53. Therefore, high levels of random lo cal genetic differentiation are likely in this species.