Data from: Contrasting diversity and demographic signals in sympatric narrow range endemic shrubs of the southwest Western Australian semi-arid zone

Comparative studies of sympatric species that integrate both phylogeographic and population genetic approaches provide insight into how demographic events and life history traits shape adaptive potential and drive species persistence. Such studies are rare for species rich and strongly structured environments, especially those of the southern hemisphere. For two sympatric, perennial shrubs of the southwest Western Australian semi-arid zone, Grevillea globosa and Mirbelia sp. Bursarioides, we assessed historical and contemporary genetic diversity and structure, demographic processes and ratios of pollen to seed dispersal. Phylogeographic structure was not detected and haplotype networks were star-like. Number of haplotypes, nucleotide diversity, haplotype diversity, and allelic diversity were significantly lower for G. globosa (h = 9, π = 0.0003, Hd = 0.309, Na = 7.650, Nea = 3.982,) than for M. sp. Bursarioides (h =16, Hd = 0.792, Na = 8.629, Nea = 4.70,). Levels of haplotype divergence and more contemporary genetic divergence and expected heterozygosity were lower for G. globosa (GST = 0.346, FST = 0.0634, He = 0.697) than for M. sp. Bursarioides (GST = 0.461, FST = 0.0907, He = 0.750), but differences were not significant. Both species exhibited signals of isolation by distance and low pollen to seed dispersal ratios (5.26:1 and 6.88:1). Grevillea globosa displayed signals of historical and contemporary demographic expansion. Results imply an important role for aspects of seed ecology that impact population demography, as well as direct dispersal and a significant contribution of seed dispersal to genetic connectivity in a semi-arid landscape.