High genetic identities between three oil mallee taxa, Eucalyptus kochii ssp. kochii ssp. plenissima and E-horistes, based on nuclear RFLP analysis

The eucalypt species Eucalyptus kochii ssp. kochii, E. kochii ssp. plenissima and E. horistes, are harvested for oil production. The genetic diversity in these taxa and their phylogenetic relationships were assessed using anonymous nuclear RFLP loci. Variation was determined for 20 individuals from 10 populations representing the three taxa. The level of diversity in the taxa was high compared to other species where RFLP surveys have been conducted, including another eucalypt species. The populations showed little differentiation, low genetic distance and high gene flow between them. Phylogenetic relationships reveal clustering of populations consistent with their geographical distribution. This analysis suggests that genetically these taxa represent a single widespread, variable species with some provenance delineation. Establishment of a breeding programme based on all populations would allow progress in genetic improvement for oil yield.