Data from: Genetic diversity and multiple origins of polyploid Atriplex nummularia Lindl. (Chenopodiaceae).

Few studies have described the genetic diversity within and between
populations of polyploid plant species despite the general acceptance of
the importance of polyploidy in plant diversification and speciation. The
genus Atriplex has a complex evolutionary history in Australia that has
included polyploidy and hybridization among perennial forms. The
octoploid, dioecious species Atriplex nummularia is proposed to have
evolved from an octoploid ancestor in the coastal semi-arid fringe of
south-western Australia, and to have spread east and diversified into taxa
which occupy edaphically different habitats. Despite interest in the
diversification of the genus, and the ecological and economic importance
of A. nummularia, there are no descriptions of the genetic structure of
the species. Nuclear microsatellite markers and principal coordinate
analysis, analysis of molecular variance, Bayesian and phenetic analyses
were used to investigate the diversity and taxonomic relationships of two
common subspecies of A. nummularia. Genetic diversity was high overall (A
= 509, A′ = 42.4, Ho = 0.824, H′ = 2.8), but values were significantly
lower in the western subspecies, A. nummularia ssp. spathulata. As in
other outbreeding, perennial species, most of the genetic diversity was
within populations (FST = 0.125). Clear divergence of subspecies was
evident in principal coordinate analysis, neighbor-joining and Bayesian
clustering analyses and the differentiation of populations was very low
within subspecies (FSC = 0.048). These findings support the taxonomic
separation of the two subspecies. Clustering patterns based on Bayesian
analyses suggested that the polyploid subspecies of A. nummularia have
multiple origins.