A Phylogeographic Analysis of Allozyme Variation among Populations of Persoonia mollis (Proteaceae)

Abstract

The phylogeography of 18 populations representing all nine subspecies within Persoonia mollis R.Br. (Proteaceae) was estimated from allozyme frequency data. Trees were constructed using UPGMA, maximum likelihood (CONTML) and maximum parsimony (FREQPARS) procedures. Major differences in topology between the UPGMA tree and other trees indicated that evolutionary rates are probably heterogeneous in different lineages in P. mollis, and that the UPGMA tree is inaccurate as it assumes constant evolutionary rates in all lineages. The maximum likelihood and maximum parsimony trees produced near-identical topologies. The major patterns produced by these trees included the early differentiation of subspecies maxima, the well-supported clade of all other P. mollis populations and, within this clade, the split into two clades that, although distinct, was weakly differentiated at their base. Within these two clades, there is a strong correlation between geographical distance between populations and the position of populations on the tree. These trees are consistent with a scenario of range expansion along two distinct paths in a southerly direction from northern refugia since the last glacial maximum, which is supported by data on the vegetation history of the area. These southern paths currently terminate in populations that share a hybrid zone of apparently secondary origin west of the Budawang Range.