A Major Disjunction in Genetic Diversity Over the Geographic Range of Acacia melanoxylon R.Br

Abstract

A study of allozyme variation in Acacia melanoxylon R. Br. in 27 populations from across the geographic range of the species indicated high genetic diversity compared to other Australian trees and plants generally. Clines of increasing genetic variability with increasing latitude were found for four measures of genetic diversity. Most of the genetic diversity is found within populations but there was an unusually high level of the variation between populations (37.7%). A distinct genetic separation between the northern and southern populations was located approximately at the Hunter River region, where there is also a disjunction in the distribution of the species. The Nei (1978) genetic distance between these populations within this species is larger than observed between some plant species. Clearly the species has evolved separately in the two regions for a considerable time.