RFLP diversity in the nuclear genome of Acacia mangium

Genetic diversity in the nuclear genome of Acacia mangium was estimated using 57 anonymous RFLP loci for 10 individuals from each of 10 natural populations representing the geographical range of the species. The level of genetic diversity varied significantly among the populations, ranging from HE=0.01 on the island of Ceram to HE=0.21 in Muting, New Guinea. The small, geographically isolated populations of Daintree, Townsville, Ceram and Sidei had low levels of diversity (HE=0.01–0.09) whereas the large New Guinea and the Cape York Peninsula populations had higher levels of diversity (HE=0.16–0.21). There was evidence of genetic differentiation between populations (θ=0.35), 75% of which was attributable to differences between four geographical regions of Cape York and Daintree–Townsville in Australia, New Guinea and Ceram–Sidei. This may reflect restrictions to gene flow associated with past expansions and contractions of rainforests which occurred with climate and sea level changes. The level of variation detected with RFLPs was higher than previously detected with allozymes, supporting speculation that allozyme coding regions are more likely to be constrained by selection than noncoding regions. The distribution of variation within and among populations was consistent for the two marker types.