A MAJOR DISJUNCTION IN GENETIC DIVERSITY OVER THE GEOGRAPHIC RANGE OFACACIA-MELANOXYLON RBR

A study of allozyme variation in Acacia melanoxylon R. Br. in 27 popul ations from across the geographic range of the species indicated high genetic diversity compared to other Australian trees and plants genera lly. Clines of increasing genetic variability with increasing latitude were found for four measures of genetic diversity. Most of the geneti c diversity is found within populations but there was an unusually hig h level of the variation between populations (37.7%). A distinct genet ic separation between the northern and southern populations was locate d approximately at the Hunter River region, where there is also a disj unction in the distribution of the species. The Nei (1978) genetic dis tance between these populations within this species is larger than obs erved between some plant species. Clearly the species has evolved sepa rately in the two regions for a considerable time.