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Aim To investigate the relationships between species attributes and genetic parameters in Australian plant species and to determine the associations in relation to predictions from population theory and previous global analyses.Location Continent of Australia. MethodsWe assembled a dataset of all known population genetic analyses of Australian plants based on neutral markers and catalogued them according to key species attributes, including range, abundance, range disjunction, biome and growth form; and genetic parameters, mean number of alleles per locus, observed and expected heterozygosity and population differentiation. We determined relationships between species attributes and genetic parameters using a maximum-likelihood, multimodel inference approach. Results We found many associations that were consistent with predictions. Species attributes with greatest effect on genetic diversity were range size, growth form, abundance and biome. The most important attributes influencing genetic differentiation were range disjunction and abundance. We found unexpected results in the effects of biome and growth form on genetic diversity, with greater diversity in the eastern biome of Australia, and lower diversity in shrubs compared to trees.Main conclusions Our analysis of genetic diversity of Australian plants showed associations consistent with predictions based on population genetics theory, with strong effects of range size, abundance and growth form. We identified a striking effect of range disjunction on population genetic differentiation, an effect that has received little attention in the literature. We also found some notable differences to global predictions, which were most likely explained by confounding effects across variables. This highlights that caution is needed when extrapolating trends from global analyses to regional floras. Identifying associations between species attributes and patterns of genetic diversity enables broadscale predictions to facilitate the inclusion of genetic considerations into conservation decision-making.

BackgroundIn order to rapidly and efficiently screen potential biofuel feedstock candidates for quintessential traits, robust high-throughput analytical techniques must be developed and honed. The traditional methods of measuring lignin syringyl/guaiacyl (S/G) ratio can be laborious, involve hazardous reagents, and/or be destructive. Vibrational spectroscopy can furnish high-throughput instrumentation without the limitations of the traditional techniques. Spectral data from mid-infrared, near-infrared, and Raman spectroscopies was combined with S/G ratios, obtained using pyrolysis molecular beam mass spectrometry, from 245 different eucalypt and Acacia trees across 17 species. Iterations of spectral processing allowed the assembly of robust predictive models using partial least squares (PLS).ResultsThe PLS models were rigorously evaluated using three different randomly generated calibration and validation sets for each spectral processing approach. Root mean standard errors of prediction for validation sets were lowest for models comprised of Raman (0.13 to 0.16) and mid-infrared (0.13 to 0.15) spectral data, while near-infrared spectroscopy led to more erroneous predictions (0.18 to 0.21). Correlation coefficients (r) for the validation sets followed a similar pattern: Raman (0.89 to 0.91), mid-infrared (0.87 to 0.91), and near-infrared (0.79 to 0.82). These statistics signify that Raman and mid-infrared spectroscopy led to the most accurate predictions of S/G ratio in a diverse consortium of feedstocks.ConclusionEucalypts present an attractive option for biofuel and biochemical production. Given the assortment of over 900 different species of Eucalyptus and Corymbia, in addition to various species of Acacia, it is necessary to isolate those possessing ideal biofuel traits. This research has demonstrated the validity of vibrational spectroscopy to efficiently partition different potential biofuel feedstocks according to lignin S/G ratio, significantly reducing experiment and analysis time and expense while providing non-destructive, accurate, global, predictive models encompassing a diverse array of feedstocks.

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Eucalypts are both a proven but largely unexplored source of woody biomass for biofuel production. Few of the some 900 species have been evaluated for cropping, yet among them are the most productive and versatile biomass species in the world, grown in over 90 countries, with species found to suit most tropical and temperate climates. The biology, science and technology underlying the breeding and growing of eucalypts and their potential for biofuel production are reviewed. How eucalypts meet sustainability and economic criteria for biofuel feedstocks, and the advantages of woody feedstocks broadly, are considered. Relevant aspects of eucalypt taxonomy, evolution, natural distribution, human dispersal, composition, domestication and biotechnology of the groups' potential as a biofuel feedstock resource are reviewed. Two case studies are outlined, illustrating species identification, domestication and harvesting processes where eucalypts are prospective biofuel feedstocks. Eucalypts are strong contenders as a universal woody biomass feedstock for biofuel.

Parental and consensus maps were constructed in an F2 inter-provenance cross of Eucalyptus globulus, using amplified fragment length polymorphism (AFLP) and microsatellite (or simple sequence repeats [SSR]) markers. The female map had 12 linkage groups and 118 markers, comprising 33 SSR and 85 AFLP loci. The male map had 14 linkage groups and 130 markers comprising 36 SSR and 94 AFLP loci. The integrated map featured 10 linkage groups and 165 markers, including 33 SSR and 132 AFLP loci, a small 11th group was identified in the male parent. Moderate segregation distortion was detected, concentrated in gender specific groups. The strongest distortion was detected in the female parent for which causal mechanisms are discussed. The inclusion of SSR markers previously mapped in several different eucalypt species within the subgenus Symphyomyrtus (E. globulus, E. camaldulensis, and predominantly E. grandis and E. urophylla), allowed comparison of linkage groups across species and demonstrated that linkage orders previously reported in E. globulus, E. grandis and E. urophylla were largely conserved.

Gene flow by pollen dispersal from forestry plantations containing introduced species, provenances or selected elite breeding material may impact on local native forest by changing the genetic diversity, introducing new genes or gene combinations, or causing the extinction of rare genotypes in adjacent native forest areas. Patterns of pollen flow can be used to assess the risk of genetic pollution of native forest areas from nearby plantations. Pollen flow in an artificial population of Eucalyptus grandis was estimated using molecular markers and paternity analysis. Microsatellite genotyping was used to identify pollen parents of progeny arrays from six mother trees. Of 329 progeny analysed, 178 (54%) were assigned to pollen parents within the population. Pollen parents located within the population were between 0-192 m from the respective mother trees, with an average pollination distance of 57.96 m. Pollination of mother trees was outcrossed, not by nearest neighbours, and displayed a preference for inter-provenance matings within the population. Progeny that could not be assigned pollen parents within the population (46%) were assumed to have resulted from pollen immigration from external sources. These pollen flow parameters provide useful information about the dynamics of pollen movement within E. grandis populations and may be used in risk assessment of gene flow from plantations to adjacent areas of native forest.

Spotted gums (genus Corymbia, section Politaria) occur as a species replacement series along the eastern seaboard of Australia, their distributions marked by regions of disjunction and sympatry. Their taxonomy remains controversial, with species assignment often challenging and reliant on knowledge of geographic origin as well as subtle morphological or leaf-oil variation. In the present paper, we explore a classification for spotted gums, without assuming predefined geographic or taxonomic groups but instead using genetic structure at microsatellite marker loci (n = 9) and a Bayesian model-based clustering approach implemented in Structure software. The C. torelliana outgroup (n = 21; section Cadagaria) formed a well resolved cluster (minimum pairwise Fst = 0.19). Four populations were evident within the spotted gums (n = 93) but structure was weak (pairwise Fst range 0.13–0.05). Geographic distance, topography and distribution disjunction were major determinants of structure, with migration among populations approximating a linear stepping-stone model. Corymbia maculata was resolved as a taxon and had the greatest genetic distance from any other population (minimum pairwise Fst 0.08). Three clusters were evident within the northern taxa but alignment with taxonomic groupings was poor. C. citriodora material from north of a major disjunction in central Queensland formed a Northern population. C. citriodora, C. variegata and C. henryi material south of this disjunction but north of the Border Range, formed a Central population, whereas a Southern population comprised C. variegata and C. henryi from predominately south of the Border Range.