DOI: 10.5061/dryad.bg684
title: Data from: Does population distribution matter? Influence of a patchy versus continuous distribution on genetic patterns in a wind-pollinated shrub

description: Aim: Uniform spatial population distributions are predicted to result in
 lower among-population genetic differentiation and higher
 within-population genetic diversity than naturally patchy distributions,
 but there have been surprisingly few attempts to isolate this effect from
 confounding factors. We studied the widespread wind-pollinated shrub
 Allocasuarina humilis that is common in a geologically-stable landscape
 characterised by long-term population persistence to test the influence of
 semi-continuous versus patchy population distributions on genetic
 patterns. We also investigated whether A. humilis shows the high
 population connectedness and genetic diversity typically associated with
 wind pollination, a relatively uncommon and little-studied syndrome in
 this landscape. Location: Heath-shrublands (‘heath’) and forests of
 south-western Australia. Methods: Populations were sampled from heath and
 forest regions, which respectively exhibited semi-continuous and patchy
 population distributions. Genetic structure and diversity were assessed
 for 27 populations using eight nuclear microsatellite markers and three
 chloroplast regions. Phylogeographic history was examined using Bayesian
 phylogeny reconstruction, parsimony analysis and tests of expansion.
 Results: High haplotype diversity is consistent with long-term population
 persistence across most of the species’ range. Nuclear markers showed low
 overall population differentiation and no geographical structure over ~900
 km, reflecting extensive pollen dispersal. For both marker types,
 patchily-distributed forest populations were substantially more
 differentiated with significantly lower within-population diversity than
 semi-continuous heath populations. Phylogeographic analysis revealed
 evidence for earlier colonization of heath than forest and recent
 expansion into wetter forests, consistent with progressive long-term
 climatic drying. Main conclusions: High population connectedness and
 genetic diversity probably resulted from wind pollination in combination
 with dioecy and long life span. Patchy population distributions appear to
 have influenced genetic structure and diversity through lower pollen and
 seed dispersal, lower effective population sizes and greater genetic
 drift. Our approach illustrates the value of minimising confounding
 variables by testing the effect of a variable ecological trait within a
 single species.
description: Microsatellite genotype
 data for Allocasuarina humilisGenotype data for 27
 Allocasuarina humilis populations assayed for 8 microsatellite
 markersAllocasuarina humilis
 microsatellite data.csvNexus file for
 Allocasuarina humilis cpDNA haplotype dataDataset consists of 25
 cpDNA haplotypes sampled from 27 populations of Allocasuarina humilis.
 Haplotypes were based on analysis of rpl32-trnL, trnQ-rps16 and trnG
 sequences. Haplotype names are consistent with those used in the Journal
 of Biogeography publication.Allocasuarina_humilis_nexus.txt