Aim Granite outcrops are prominent throughout the world and harbour many endemic species. Their topographic complexity and range of environments have led to the hypothesis that they act as refugia facilitating the persistence of species through climate change. We evaluate this hypothesis by investigating the phylogeographic patterns in a common granite endemic shrub. Location Granite outcrops of the Southwest Australian Floristic Region. Methods Chloroplast haplotypes of 89 Kunzea pulchella individuals from 16 granite outcrops were determined from sequences of three chloroplast intergenic spacer regions. Phylogenetic reconstruction and divergence dating was inferred using Bayesian and Parsimony analyses and phylogenetic relationships between haplotypes were examined in relation to geographic distributions. Nuclear diversity and differentiation of populations were assessed through analysis of 11 nuclear microsatellite loci across 384 individuals from the 16 granite outcrops. Results Kunzea pulchella exhibited low haplotype and allelic diversity within outcrops and high levels of divergence among outcrops, indicating an ancient restriction to specific outcrops with genetic drift as the main driver of evolution. Two divergent lineages were revealed in the chloroplast phylogeny dating to the Pliocene and potentially reflecting the initial impact of increased aridity prior to isolation on individual outcrops. Main conclusions Rather than uncovering the typical pattern for Pleistocene refugia with contraction to, and expansion from particular granite outcrops, we observed persistence, prolonged isolation and divergence of populations. We suggest the persistence of K. pulchella on multiple outcrops through a period of considerable climatic change may be a result of broad climatic tolerances or contraction and expansion dynamics operating at microrefugial scales within outcrops. Our observations of low haplotype and allelic diversity within populations of K. pulchella provide some support for the latter. The enduring nature of K. pulchella and evolutionary potential of populations on individual outcrops accentuates the value of these environments for biodiversity conservation planning in a changing climate.

Aim Granite outcrops may be able to act as refugia for species during adverse climate change, owing to their topographic complexity. We assessed this hypothesis by examining phylogeographical patterns in a common, geographically widespread granite endemic, Stypandra glauca (Hemerocallidaceae). Location Granite outcrops of the Southwest Australian Floristic Region, Western Australia. Methods Twenty‐four tetraploid individuals of the granite endemic Stypandra glauca were sampled from each of 12 granite outcrops: 7 from a mesic environment and 5 from the semi‐arid region. Phylogenetic reconstruction and divergence‐dating was achieved using Bayesian and parsimony analyses of chloroplast haplotypes from 90 individuals. Nuclear diversity and population differentiation were analysed across all individuals using 10 microsatellite loci. Results Stypandra glauca exhibited high (chloroplast) or moderate (nuclear) levels of divergence among, and low diversity within, outcrops. Haplotype diversity was high in both sampling regions, and each haplotype was unique to one outcrop. There was little correlation between geographical and genetic distance. Both nuclear and chloroplast diversity were higher in southern (mesic) outcrops than in northern (semi‐arid) outcrops, although the level of chloroplast divergence among outcrops was similar for both climatic regions. Main conclusions The levels of divergence and low diversity revealed in S. glauca support a scenario of prolonged isolation and persistence on granite outcrops in both mesic and semi‐arid climatic regions, with no evidence of contraction–expansion dynamics across the outcrop network. The higher levels of diversity in the southern populations may result from the maintenance of a larger effective population size in southern regions, which retained more mesic climates during drier glacial periods. Although the climatic conditions differ between outcrops in this study, our results indicate that outcrops in both regions have harboured S. glauca throughout climatic changes, accentuating the value of these habitats to biodiversity conservation under future changing climate.

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 characterized 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. Phylogeographical 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 c. 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. Phylogeographical 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 minimizing confounding variables by testing the effect of a variable ecological trait within a single species. Population code; dominant vegetation type; N, number of adults sampled; A r , mean allelic richness per locus, estimated using rarefaction with a minimum sample size of 11 individuals; N p , total number of private alleles; H o , observed heterozygosity; H e , unbiased expected heterozygosity; F IS , inbreeding coefficient; *F IS > 0 at P ≤ 0.05; means across loci are given with standard errors in parentheses.

Aim Terrestrial plant ecology and evolution is significantly influenced by the phenomenon of fire, but studies of its potential impact on intraspecific genetic variation and phylogeography are rare. This understanding will be important for predicting the biogeographical consequences of changing fire regimes under global climate change. Here, we asked whether changing historical fire regimes, together with climatic and geological history, have influenced phylogeographical patterns in a fire-ephemeral vine. We also asked whether demographic stochasticity associated with a fire-ephemeral life history results in nuclear genetic drift as expected from spatio-temporal patchiness, or if this effect is buffered by the connectivity and diversity afforded by a persistent soil seed bank.Location The fire-prone, mediterranean-type climate region of south-western Australia.Methods We used Bayesian phylogeny reconstruction and statistical tests of demographic expansion based on variation at three non-coding chloroplast sequence regions (atpF, ndhF-rpl32, psbD-trnT) to reconstruct phylogeographical history. Nuclear diversity and population structure at 11 microsatellite loci were investigated for evidence of genetic drift.Results Evidence for prolonged persistence and a lack of vicariance within the species range was found, together with strong evidence of historical demographic expansion. Contrary to expectations, there was little evidence of nuclear genetic drift despite strong, above-ground spatio-temporal population patchiness.Main conclusions Our findings suggest that a late Pleistocene increase in fire frequency may have led to demographic expansion in this fire-ephemeral species; alternatively, the expansion signal may be an inherent feature of fire ephemerals with a persistent soil seed bank. Prolonged climatic stability has likely fostered persistence within the species range in contrast to contraction and vicariance. The notable lack of genetic drift implies a role for ample pollen dispersal and a long-lived soil seed bank in the maintenance of diversity and connectivity in an otherwise stochastic, fire-driven system.

Aim Fire regimes are a significant driver of plant adaptation and evolution, and projected changes under a changing climate will have significant implications for demographic and evolutionary responses of plant populations in fireprone regions globally. We tested predictions regarding level and pattern of genetic variation within a model post-fire facultative seeder, Bossiaea ornata (Fabaceae), that exhibits a combination of both post-fire resprouting and seeding strategies.Location Fire-prone forests in the mediterranean-climate region of southwestern Australia.Methods We genotyped individuals with eight microsatellite markers and four non-coding chloroplast sequence regions to assess population genetic variation and reconstruct phylogeographical history.Results Extremely high levels of chloroplast (H D = 0.95) and nuclear (H E = 0.81) diversity were detected. Nuclear population differentiation was weak (F ST = 0.06) and chloroplast phylogeographical structure was absent. A significant excess of rare chloroplast haplotypes was detected (D, F S , R 2 ; all P < 0.01), consistent with demographic expansion.Main conclusions Results suggest that a facultative seeding life-history affords the benefits of both obligate resprouting and obligate seeding strategies in terms of resistance and resilience to fire. High diversity and low differentiation are likely driven by long generational overlap (resprouter feature), regular post-fire population supplementation from a persistent soil seed bank (seeder feature) and longterm stability. Expansion signals may be a feature of species with regular, synchronous post-fire recruitment from a soil seed bank, rather than evidence of a single range or demographic expansion event, as typically interpreted. The facultative seeding strategy may therefore offer resilience to potential increases in fire frequency under a changing climate in fire-prone regions.