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1.  Genetic connectivity and inter-population seed dispersal of Banksia hookeriana at the landscape scale 
Annals of Botany  2010;106(3):457-466.
Background and Aims
Landscape genetics combines approaches from population genetics and landscape ecology, increasing the scope for conceptual advances in biology. Banksia hookeriana comprises clusters of individuals located on dune crests (geographical populations) physically separated by uninhabitable swales, with local extinctions common through frequent fire and/or severe drought.
A landscape genetics approach was used to explore landscape-scale genetic connectivity and structure among geographical populations of B. hookeriana on 18 physically separated dunes located within a heterogeneous landscape of 3 × 5 km. These geographical populations were separated by approx. 0·1 to >1 km of unsuitable intervening swale habitat. Using 11 highly variable microsatellite loci, we utilized a Bayesian approach to identify genetic discontinuities within and between these geographical populations. Population allocation tests were then used to detect inter-dune seed dispersal inferred from assignment of individuals to a source population other than that from which they were collected.
Key Results
For the modal number of genetically distinct clusters (n = 17 genetic populations), two coincided with the geographical (dune) populations, eight spanned two to four geographical populations, and the remaining seven were spread among various parts of the sampled dunes, so that most geographical populations were spatially defined mosaics of individuals (subpopulations) belonging to two or more genetic populations. We inferred 25 inter-dune immigrants among the 582 individuals assessed, with an average distance between sink and source dunes of 1·1 km, and a maximum of 3·3 km.
The results show that genetic structure in an apparently strongly spatially structured landscape is not solely dependent on landscape structure, and that many physically defined geographical populations were genetic mosaics. More strikingly, there were physically separated individuals and groups of individuals that were part of the same genetically defined populations. We attribute this mismatch between spatially and genetically defined population structure to the varying closeness of the dunes and the ability of seeds to disperse long distances.
PMCID: PMC2924833  PMID: 20647226
Banksia; landscape genetics; landscape connectivity; population assignment; seed dispersal; South West Australian Floristic Region
2.  The fire ephemeral Tersonia cyathiflora (Gyrostemonaceae) germinates in response to smoke but not the butenolide 3-methyl-2H-furo[2,3-c]pyran-2-one 
Annals of Botany  2010;106(2):381-384.
Background and Aims
Tersonia cyathiflora (Gyrostemonaceae) is a fire ephemeral with an obligate requirement for smoke to germinate. Whether it is stimulated to germinate by 3-methyl-2H-furo[2,3-c]pyran-2-one (karrikinolide, KAR1), the butenolide isolated from smoke that stimulates the germination of many other smoke-responsive species, is tested.
Seeds of T. cyathiflora were buried in autumn following collection and were exhumed 1 year later, as this alleviates dormancy and enables seeds to germinate in response to smoke-water. Exhumed seeds were tested with smoke-water and KAR1. Fresh preparations of these solutions were again tested on seeds exhumed 2 months later under a broader range of conditions. They were also tested on Grevillea eriostachya (Proteaceae) and Stylidium affine (Stylidiaceae) to confirm the activity of KAR1.
Key Results
T. cyathiflora seeds germinated in response to smoke-water but not to KAR1. In contrast, G. eriostachya and S. affine germinated in response to both smoke-water and KAR1.
Although many smoke-responsive seeds germinate in the presence of KAR1, this does not apply universally. This suggests that other chemical(s) in smoke-water may play an important role in stimulating the germination of certain species.
PMCID: PMC2908171  PMID: 20605804
Butenolide; germination; karrikinolide; smoke; 3-methyl-2H-furo[2,3-c]pyran-2-one; Grevillea; Stylidium; Tersonia cyathiflora; Gyrostemonaceae
3.  Correlations between leaf toughness and phenolics among species in contrasting environments of Australia and New Caledonia 
Annals of Botany  2008;103(5):757-767.
Background and Aims
Plants are likely to invest in multiple defences, given the variety of sources of biotic and abiotic damage to which they are exposed. However, little is known about syndromes of defence across plant species and how these differ in contrasting environments. Here an investigation is made into the association between carbon-based chemical and mechanical defences, predicting that species that invest heavily in mechanical defence of leaves will invest less in chemical defence.
A combination of published and unpublished data is used to test whether species with tougher leaves have lower concentrations of phenolics, using 125 species from four regions of Australia and the Pacific island of New Caledonia, in evergreen vegetation ranging from temperate shrubland and woodland to tropical shrubland and rainforest. Foliar toughness was measured as work-to-shear and specific work-to-shear (work-to-shear per unit leaf thickness). Phenolics were measured as ‘total phenolics’ and by protein precipitation (an estimate of tannin activity) per leaf dry mass.
Key Results
Contrary to prediction, phenolic concentrations were not negatively correlated with either measure of leaf toughness when examined across all species, within regions or within any plant community. Instead, measures of toughness (particularly work-to-shear) and phenolics were often positively correlated in shrubland and rainforest (but not dry forest) in New Caledonia, with a similar trend suggested for shrubland in south-western Australia. The common feature of these sites was low concentrations of soil nutrients, with evidence of P limitation.
Positive correlations between toughness and phenolics in vegetation on infertile soils suggest that additive investment in carbon-based mechanical and chemical defences is advantageous and cost-effective in these nutrient-deficient environments where carbohydrate may be in surplus.
PMCID: PMC2707862  PMID: 19098067
Antiherbivore defence; leaf toughness; mechanical defence; chemical defence; phenolics; trade-offs

Results 1-3 (3)