MULTIPLE PATERNITY IN EUCALYPTUS-RAMELIANA (MYRTACEAE)

Estimates of the level of multiple paternity/correlated outcrossing wi thin and between fruits in a predominantly outbreeding population of t he bird-pollinated mallee, Eucalyptus rameliana, were made using six a llozyme loci. The correlation of outcrossed paternity (r(p)) was posit ive and significant within fruits (0.26) and the effective number of m ates for a single fruit was estimated to be 3.85. This correlation was attributed to the low number of potential male parents and pollen-bea ring flowers available at any one time in the population. Although con sistent with suggestions that correlation of paternity may be a genera l feature of animal-pollinated plants, the level in E. rameliana was r emarkably low considering its population size and phenology. There was no significant correlation of paternity between fruits, probably beca use flowers were pollinated at different times during the long season. Individual plants differed greatly in both male and female contributi ons to the next generation, with a small proportion of genotypes locat ed in a small area contributing at least half of the gene pool of the seeds stored in the canopy. In contrast, the male contribution is prob ably from a wider area. The specialization of floral structure and phe nology in E. rameliana for bird-pollination has probably contributed t o correlation of paternity within fruits because there are fewer male parents available at any one time than in mass-flowering species. Howe ver, the behaviour of the bird pollinators also promotes pollen disper sal and multiplicity of paternity, factors which would be particularly significant when the female contribution to the gene pool is concentr ated in a few plants.