Subgenus Eucalyptus Research Articles

Evolutionary history determines how plant productivity responds to phylogenetic diversity and species richness

The relationship between biodiversity and ecosystem function has received a great deal of attention in ecological research and recent results, from re-analyses, suggest that ecosystem function improves with increases in phylogenetic diversity. However, many of these results have been generalized across a range of different species and clades, and plants with different evolutionary histories could display different relationships between biodiversity and ecosystem function. To experimentally test this hypothesis, we manipulated species richness and phylogenetic diversity using 26 species from two subgenera of the genus Eucalyptus (subgenus Eucalyptus and subgenus Symphyomyrtus). We found that plant biomass (a measurement of ecosystem function) sometimes, but not always, responded to increases in species richness and phylogenetic diversity. Specifically, Symphyomyrtus plants showed a positive response while no comparable effect was observed for Eucalyptus plants, showing that responses to biodiversity can vary across different phylogenetic groups. Our results show that the impacts of evolutionary history may complicate the relationship between the diversity of plant communities and plant biomass.

Microsatellite markers for Eucalyptus pilularis (Subgenus Eucalyptus); sourcing genetic markers outside the subgenus

AbstractMicrosatellite markers remain the most broadly used molecular marker in eucalypt genetics. A major advantage of microsatellite markers is that they often transfer readily between related taxa circumventing the need to develop new markers de novo in each species. Markers have been developed for a number of species of major economic importance, mainly from the Subgenus Symphyomyrtus, but these may also be available for use in species of lesser economic importance from other subgenera. Here we report on the sourcing of microsatellite markers for E. pilularis (Subgenus Eucalyptus (Formerly Monocalyptus)) from species outside the subgenus. Ninety-seven precent (60 out of 62) of loci that amplified in the source taxon (E. grandis) also amplified in the target taxon E. pilularis. By characterising them on a diversity panel (n=24) and a pedigree, a subset of 41 loci were distilled out that could be scored reliably and were polymorphic (Mean unbiased heterozygosity= 0.81). Predictions of efficient microsatellite marker transfer among eucalypts based on low evolutionary divergence have largely been borne out and are congruent with accumulating evidence of low sequence divergence within Eucalyptus. Upon this favourable background for microsatellite marker transfer, this study indicates highly efficient transfer is possible by identifying loci with broad PCR optima and adoption of approaches that favour cross-species transfer.

Nematodes from galls on Myrtaceae. V. Fergusobia from large multilocular shoot bud galls from Angophora and Eucalyptus in Australia, with descriptions of six new species.

Six new species of Fergusobia, from large multilocular shoot bud galls on two species of Angophora and four species of Eucalyptus from both subgenera Eucalyptus and Symphyomyrtus, are described. Fergusobia cosmophyllae Davies n. sp. is characterized by the combination of a C-shaped parthenogenetic female with a short arcuate conoid tail, a broad (small a ratio) arcuate infective female with an hemispherical tail tip, and an arcuate to J-shaped male with broad, angular spicules and short bursa. Fergusobia delegatensae Davies n. sp. has an open C-shaped parthenogenetic female with a broadly conoid tail, an infective female of variable shape with an hemispherical tail tip, and a male of open C-shape with a crenate bursa that arises 40-70% along the length of the body from the tail tip and terminates just anterior to the cloaca. Fergusobia diversifoliae Davies n. sp. has a C-shaped parthenogenetic female with a conoid tail, an arcuate infective female with a hemispherical tail tip, and an arcuate, C- or J-shaped male with angular spicule and a long peloderan bursa. Fergusobia floribundae Davies n. sp. has a C-shaped parthenogenetic female with a narrow, arcuate, conoid tail, an arcuate infective female with a hemispherical tail tip, and an arcuate or J-shaped male with an angular spicule and a short to mid-body length peloderan bursa. Fergusobia minimus Lisnawita n. sp. has a C-shaped parthenogenetic female with a conoid tail, an arcuate to open C-shaped infective female with a hemispherical tail tip, and an arcuate to open C-shaped male with an angular spicule and a peloderan bursa arising at about 10-30% of body length. Fergusobia pimpamensis Davies n. sp. has an open C to C-shaped parthenogenetic female with a narrow conoid tail, an arcuate to open C-shaped infective female with a hemispherical tail tip, and an arcuate to C-shaped male with an arcuate spicule and a long, crenate, peloderan bursa. An inventory of all known Fergusobia/Fergusonina associations from terminal shoot bud galls is presented. The larval shield morphology of the associated mutualistic Fergusonina species is discussed where known. Analyses of DNA sequences of D2/D3 and COI suggested that the six new species are distributed between three clades of Fergusobia.

Specificity and sensitivity of plant odor-detecting olfactory sensory neurons in Ctenarytaina eucalypti (Sternorrhyncha: Psyllidae)

The blue gum psyllid, Ctenarytaina eucalypti (Sternorrhyncha: Psyllidae), is an economic threat to Eucalyptus subgenus Symphyomyrtus plantations worldwide. To date, no generally applicable control method is available and the potential for semiochemical-based monitoring or control methods has not yet been investigated. Hence, we conducted the first study on the olfactory sense of C. eucalypti, investigating the specificity and sensitivity of its olfactory sensory neurons (OSNs) to host plant volatiles using single sensillum recordings (SSR). Synthetic compounds were selected from published identifications of Eucalyptus volatiles and after analysis of headspace collections from Eucalyptus cordata. The antenna of C. eucalypti carries four cavities containing olfactory sensilla (S1–S4). Our recordings revealed that each of these sensilla houses three OSNs that could be distinguished electrophysiologically based on spike amplitude differences (A, B, and C neuron with large, intermediate, and small amplitude, respectively). The A neuron in sensillum S1 responded primarily to β-caryophyllene and weaker to β-ocimene, whereas the accompanying B-neuron responded strongly and very specifically to linalool. Furthermore, the B-neuron in both S2 and S3 responded strongly to 1-hexanol, Z3-hexenol, and Z3-hexenyl acetate. OSNs in S4 responded only weakly to a few of the synthetic compounds. Response thresholds in strongly responding OSNs to putative key compounds were close to the 1ng dose on the filter paper and responses exhibited a phasic-tonic profile irrespective of compound dose. C. eucalypti may use the physiologically active compounds for long-range host finding. Future laboratory and field experiments will reveal whether plant volatiles can be used in the management and monitoring of C. eucalypti.

Localization of oleuropeyl glucose esters and a flavanone to secretory cavities of Myrtaceae.

We report the widespread occurrence of structurally diverse oleuropeyl glucose esters, including the new diester eucaglobulin B, localized specifically to the essential oil secretory cavities of myrtaceous species. Clear taxonomic patterns in the composition of cavity extracts within the genus Eucalyptus are shown with species from subgenus Symphyomyrtus dominated by oleuropeyl glucose esters and species from subgenus Eucalyptus dominated instead by the flavanone, pinocembrin. We also examined the intra-species occurrence of oleuropeyl glucose esters by quantifying the abundant constituents cuniloside B and froggattiside A in trees from two populations of Eucalyptus polybractea R.T. Baker. All trees contained both compounds, which were positively correlated with total essential oil concentration. This apparent ubiquity of oleuropeyl glucose esters at both intra- and inter-specific levels in Eucalyptus is indicative of important physiological or ecological functions. The significance of their prevalence and the sequestration of these esters and also pinocembrin to the extracellular domain of secretory cavities is discussed in light of their potential biological activities and our findings that they are spatially segregated to the exterior of cavity lumina. The localization of oleuropeyl glucose esters to a specific and isolatable tissue type has the potential to aid in future elucidation of function and biosynthesis.

Oldest known Eucalyptus macrofossils are from South America.

The evolutionary history of Eucalyptus and the eucalypts, the larger clade of seven genera including Eucalyptus that today have a natural distribution almost exclusively in Australasia, is poorly documented from the fossil record. Little physical evidence exists bearing on the ancient geographical distributions or morphologies of plants within the clade. Herein, we introduce fossil material of Eucalyptus from the early Eocene (ca. 51.9 Ma) Laguna del Hunco paleoflora of Chubut Province, Argentina; specimens include multiple leaves, infructescences, and dispersed capsules, several flower buds, and a single flower. Morphological similarities that relate the fossils to extant eucalypts include leaf shape, venation, and epidermal oil glands; infructescence structure; valvate capsulate fruits; and operculate flower buds. The presence of a staminophore scar on the fruits links them to Eucalyptus, and the presence of a transverse scar on the flower buds indicates a relationship to Eucalyptus subgenus Symphyomyrtus. Phylogenetic analyses of morphological data alone and combined with aligned sequence data from a prior study including 16 extant eucalypts, one outgroup, and a terminal representing the fossils indicate that the fossils are nested within Eucalyptus. These are the only illustrated Eucalyptus fossils that are definitively Eocene in age, and the only conclusively identified extant or fossil eucalypts naturally occurring outside of Australasia and adjacent Mindanao. Thus, these fossils indicate that the evolution of the eucalypt group is not constrained to a single region. Moreover, they strengthen the taxonomic connections between the Laguna del Hunco paleoflora and extant subtropical and tropical Australasia, one of the three major ecologic-geographic elements of the Laguna del Hunco paleoflora. The age and affinities of the fossils also indicate that Eucalyptus subgenus Symphyomyrtus is older than previously supposed. Paleoecological data indicate that the Patagonian Eucalyptus dominated volcanically disturbed areas adjacent to standing rainforest surrounding an Eocene caldera lake.

Historical biogeographical patterns in continental Australia: congruence among areas of endemism of two major clades of eucalypts.

Published phylogenies of two eucalypt clades, red bloodwoods Corymbia subgenus Corymbia and eudesmids Eucalyptus subgenus Eudesmia (Myrtaceae), were combined for an analysis of historical biogeographical area relationships within continental Australia. The method of paralogy-free subtree analysis was used to eliminate geographical paralogy; the paralogy-free subtrees were coded as characters for parsimony analysis to find the minimal and area cladogram, which proved to be informative of a continent-wide pattern. The eucalypt fossil record and molecular dating studies allow an interpretation of the biogeographical history in terms of major vicariance events that date from the early Paleogene. The summary area cladogram shows the wet jarrah forest region of South-West Western Australia, a region of high endemism, as the earliest to differentiate from all other areas, isolated by marine inundation across southern Australia and climatic cooling in the Late Eocene-Early Oligocene. From about this time, regionalization continued, with warmer conditions and monsoonal climate developing in central and northern Australia, and cooling in the south-east. Northern and eastern humid and semi-humid areas were related as a track, but with increased aridity in the interior of the continent, the monsoonal climate contracted northwards. The Australian Monsoon Tropics (AMT: Kimberley, Top End, Arnhem, Cape York and inland north-east Queensland) differentiated from eastern areas (Queensland wet tropics to McPherson-Macleay). Our results also show all arid and semi-arid regions as related, suggestive of a historically cohesive interior biota rather than repeated colonizations of the interior from the periphery of the continent. Climate largely differentiates hot arid areas in the north (Pilbara, Northern and Central deserts) from arid areas in the south (south-west interzone, Wheatbelt, Goldfields and Great Victoria Desert). © The Willi Hennig Society 2010.

Two new mallee Eucalypts (Myrtaceae) from Gippsland, Victoria

Two new species of the subgenus Eucalyptus are described. Eucalyptus ornans, Avon Peppermint, is an extremely rare mallee form of peppermint of the series Radiatae occurring at the Avon Channels to the north of Maffra in the Central Gippsland region of Victoria. Eucalyptus forresterae, Brumby Sallee, is a restricted, shrubby or whipstick mallee of the series Longitudinales occurring near Nunniong Plateau and above Buchan River Falls at Native Dog Flat in East Gippsland. The distribution, ecology, affinity and conservation status of each taxon are discussed, as are the morphological features of the series to which each belongs.

Species differentiation and gene flow in the Blackbutts (genus Eucalyptus subgenus Eucalyptus section Pseudophloius)

The significance of the taxonomic distinction of two species of Blackbutt was studied by analysing patterns of genetic (microsatellite markers; n = 13) and phenetic (capsule morphology) differentiation. Analysis of genetic structure using a Bayesian modelling approach on range-wide samples of both taxa (n = 457) showed the major division was within the more widely distributed species, Eucalyptus pilularis, and not aligned with taxonomy. Comparisons of intra- and inter-taxon genetic differentiation in paired-samples of taxa from each of four locations spanning the distribution of the more restricted E. pyrocarpa, showed that around twice as much variation was found among locations within taxa, than between taxa. Despite the lack of differentiation at effectively neutral microsatellite markers, significant phenetic differences (including capsule size) were evident between taxa at most sites. A landscape mosaic of taxa, coincident with changes in elevation, vegetation and soil types, suggested some phenetic differences were probably adaptive and spatial differentiation was stabilised by environmental factors. An absence of morphological intermediates and a lack of correlation in the rankings of locus inter-taxon differentiation (PhiBT) across locations, was consistent with parapatric origins for E. pyrocarpa. We conclude the taxa are at the lower end of the speciation spectrum and might best be viewed as ecotypes, divergent in evolutionary potential, but with genomes broadly permeable to inter-taxa gene flow. Gene exchange between plantings of E. pilularis and nearby E. pyrocarpa forest is likely as the two taxa appear to have few barriers to reproduction.

A Metabolomic Approach to Identifying Chemical Mediators of Mammal–Plant Interactions

Different folivorous marsupials select their food from different subgenera of Eucalyptus, but the choices cannot be explained by known antifeedants, such as formylated phloroglucinol compounds or tannins, or by nutritional quality. Eucalypts contain a wide variety of plant secondary metabolites so it is difficult to use traditional methods to identify the chemicals that determine food selection. Therefore, we used a metabolomic approach in which we employed (1)H nuclear magnetic resonance spectroscopy to compare chemical structures of representatives from the two subgenera and to identify chemicals that consistently differ between them. We found that dichloromethane extracts of leaves from most species in the subgenus Eucalyptus differ from those in Symphyomyrtus by the presence of free flavanones, having no substitution in Ring B. Although flavanoids are known to deter feeding by certain insects, their effects on marsupials have not been established and must be tested with controlled feeding studies.

Phylogeny and classification of Eucalyptus subgenus Eudesmia (Myrtaceae) based on nuclear ribosomal DNA, chloroplast DNA and morphology

Phylogenetic analysis of Eucalyptus subgenus Eudesmia is presented on the basis of the following three datasets: sequences of the internal transcribed spacer (ITS) and the external transcribed spacer (ETS) regions from nuclear rDNA, sequences of the psbA–trnH intergenic spacer region from chloroplast DNA, and morphological characters, including stamen bundling, operculum development, seeds and trichomes. Studies of floral development were essential for understanding the morphology of mature flowers and interpretation of synapomorphy and homoplasy. A summary phylogeny was constructed from a maximum parsimony analysis of those nodes coded as characters that had support in the molecular trees together with morphological characters. A revised infra-subgeneric classification is presented on the basis of the summary phylogeny, and compared with classifications of Hill and Johnson (1998) and Brooker (2000). Differences relate to relationships between clades and taxonomic rank (sections, series and subseries) and valid names of Brooker (2000) are conserved where possible. One main clade of 14 species (section Limbatae), many of mallee growth form, was found in all analyses; this clade is distributed in the South-West of Western Australia and adjacent Interzone and desert areas. A second main clade (section Complanatae) occurs in the northern and eastern tropical and subtropical regions of Australia, including Kimberley, Arnhem, Queensland and New South Wales. This section includes E. tetrodonta, previously treated as an isolated taxon in a monotypic section; however, this species is related to E. baileyana, E. similis, E. lirata and series Miniatae. The hypothesised phylogeny provides a framework for further analyses of biogeography and ecology, including functional traits.

Cross‐species amplification of Eucalyptus microsatellite loci

This study examined the interspecific amplification of nuclear microsatellite loci developed mainly for eucalypts in the subgenus Symphyomyrtus across five species within the second most speciose subgenus, subgenus Eucalyptus. A set of eight to 10 loci, depending on taxon, have been identified that are highly variable and easily scored. The successful transfer of microsatellite loci to these eucalypt species sidesteps the expensive and time-consuming development of species-specific microsatellite libraries. This primer set will enable the examination and cross-species comparison of the genetic resources of commercially and ecologically important members of the subgenus Eucalyptus.

Ribosomal DNA pseudogenes are widespread in the eucalypt group (Myrtaceae): implications for phylogenetic analysis

AbstractPseudogenes from the 18S−5.8S−26S cistron of nuclear ribosomal DNA are reported in the eucalypt group (Myrtaceae), which includes seven genera. Putative pseudogenes are identified by a range of sequence comparisons including: the number of CpG and CpNpG methylation sites, GC content, estimated secondary structure stability of internal transcribed spacer transcripts, the presence of conserved motifs, patterns of sequence relationships and inferred substitution patterns. These comparisons indicate that pseudogenes are widespread, being evident in Eucalyptus (subgenera Eucalyptus and Eudesmia), Corymbia (extracodical sections Rufaria, Ochraria and Blakearia), Angophora, Stockwellia quadrifida and Arillastrum gummiferum. At least six sequences used in previous phylogenetic studies are identified as pseudogenes, and a further 10 pseudogenes are newly sequenced here. Gene trees place pseudogenes in a number of distinct lineages: pseudogenes from Eucalyptus group with other Eucalyptus sequences, those from Corymbia and Angophora group with other Corymbia/Angophora sequences, that from Stockwellia groups with other sequences from the Eucalyptopsis group, and that from Arillastrum is placed as sister to the other included sequence of Arillastrum. Some pseudogenes in Eucalyptus, Corymbia and Angophora represent “deep” ribosomal DNA paralogues that pre‐date species differentiation in these groups, and a recombination analysis shows no evidence of recombination between putative pseudogenes and their functional counterparts. The presence of divergent paralogues presents both challenges and opportunities for the reconstruction of eucalypt phylogenies using ribosomal DNA sequences. Phylogenetic data sets should include only orthologous sequences, but different paralogues potentially provide additional, independent, character sets for phylogenetic analyses.© The Willi Hennig Society 2007.

Multiplexed Microsatellite Markers for the Genetic Analysis of Eucalyptus leucoxylon (Myrtaceae) and Their Utility for Ecological and Breeding Studies in other Eucalyptus Species

Eucalyptus leucoxylon is a widespread woodland tree species found in southeastern Australia that has suffered from, and continues to be, threatened by the impacts of habitat clearance and degradation. Populations now consist predominantly of scattered individuals, and their conservation status is of increasing concern. We report the development and characterization of a set of eight highly polymorphic microsatellite loci for E. leucoxylon. The loci can be amplified in three PCR multiplexes and electrophoresed in a single lane, allowing rapid throughput of large numbers of samples. A total of 111 alleles were detected in 68 individuals with an average of 12.3 alleles per locus, a mean expected heterozygosity of 0.83, and a mean observed heterozygosity of 0.72. The combined probabilities of identity and probabilities of paternity exclusion allow an extremely precise level of individual identification, indicating that these microsatellite markers will be ideal for population genetic and parentage-type studies in E. leucoxylon. The markers also exhibited an average of 76% conservation within the subgenus Symphyomyrtus, to which E. leucoxylon belongs, and 53% conservation across other subgenera of Eucalyptus, demonstrating the potential of these markers in ecological and breeding studies in a wide range of Eucalyptus species.

Seedling responses of four Australian tree species to toxic concentrations of manganese in solution culture

Little is known about the responses of Australian plants to excess metal, including Mn. It is important to remedy this lack of information so that knowledgeable decisions can be made about managing Mn contaminated sites where inhabited by Australian vegetation. Acacia holosericea, Melaleuca leucadendra, Eucalyptus crebra and Eucalyptus camaldulensis were grown in dilute solution culture for 10 weeks. The seedlings ( 42 days old) were exposed to six Mn treatments viz., 1, 8, 32, 128, 512 and 2048 muM. The order of tolerance to toxic concentrations of Mn was A. holosericea congruent to = E. crebra < M. leucadendra < E. camaldulensis, the critical external concentrations being approximately 5.1, 5.0, 21 and 330 muM, respectively. The critical tissue Mn concentrations for the youngest fully expanded leaf and total shoots were, respectively, 265 and 215 mug g(-1) DM for A. holosericea, 445 and 495 mug g(-1) DM for M. leucadendra, 495 and 710 mug g(-1) DM for E. crebra and 7230 and 6510 mug g(-1) DM for E. camaldulensis. The high tolerance of E. camaldulensis ( as opposed to the sensitivity of E. crebra) to excess Mn raises concern about fauna feeding on the plant and is consistent with hypotheses suggesting the Eucalyptus subgenus Symphomyrtus is particularly tolerant of stress, including excess Mn. The results from this paper provide the first comprehensive combination of growth responses, critical external concentrations, critical tissue concentrations and plant toxicity symptoms for three important Australian genera, viz., Eucalyptus, Acacia and Melaleuca, for use in the management of Mn toxic sites.

Australian biogeographical connections and the phylogeny of large genera in the plant family Myrtaceae

AbstractAimTo compare the phylogeny of the eucalypt and melaleuca groups with geological events and ages of fossils to discover the time frame of clade divergences.LocationAustralia, New Caledonia, New Guinea, Indonesian Archipelago.MethodsWe compare published molecular phylogenies of the eucalypt and melaleuca groups of the plant family Myrtaceae with geological history and known fossil records from the Cretaceous and Cenozoic.ResultsThe Australasian eucalypt group includes seven genera, of which some are relictual rain forest taxa of restricted distribution and others are species‐rich and widespread in drier environments. Based on molecular and morphological data, phylogenetic analyses of the eucalypt group have identified two major clades. The monotypicArillastrumendemic to New Caledonia is related in one clade to the more species‐richAngophora,CorymbiaandEucalyptusthat dominate the sclerophyll vegetation of Australia. Based on the time of rifting of New Caledonia from eastern Gondwana and the age of fossil eucalypt pollen, we argue that this clade extends back to the Late Cretaceous. The second clade includes three relictual rain forest taxa, withAllosyncarpiafrom Arnhem Land the sister taxon toEucalyptopsisof New Guinea and the eastern Indonesian archipelago, andStockwelliafrom the Atherton Tableland in north‐east Queensland. As monsoonal, drier conditions evolved in northern Australia, Arnhem Land was isolated from the wet tropics to the east and north during the Oligocene, segregating ancestral rain forest biota. It is argued also that the distribution of species inEucalyptopsisandEucalyptussubgenusSymphyomyrtusendemic in areas north of the stable edge of the Australian continent, as far as Sulawesi and the southern Philippines, is related to the geological history of south‐east Asia‐Australasia. Colonization (dispersal) may have been aided by rafting on micro‐continental fragments, by accretion of arc terranes onto New Guinea and by land brought into closer proximity during periods of low sea‐level, from the Late Miocene and Pliocene. The phylogenetic position of the few northern, non‐Australian species ofEucalyptussubgenusSymphyomyrtussuggests rapid radiation in the large Australian sister group(s) during this time frame. A similar pattern, connecting Australia and New Caledonia, is emerging from phylogenetic analysis of theMelaleucagroup (Beaufortiasuballiance) within Myrtaceae, withMelaleucabeing polyphyletic.Main conclusionThe eucalypt group is an old lineage extending back to the Late Cretaceous. Differentiation of clades is related to major geological and climatic events, including rifting of New Caledonia from eastern Gondwana, development of monsoonal and drier climates, collision of the northern edge of the Australian craton with island arcs and periods of low sea level. Vicariance events involve dispersal of biota.

A comparative study of interspecific variation in fruit size among Australian eucalypts

We examined variation in woody fruit size among 362 Australian Eucalyptus species with respect to predictions relating fruit size to fire exposure and rainfall. Predictions for fruit size variation were established that focussed on selection for small or large seeds, given a positive allometric relationship between fruit and seed size within the genus, and on the potential for fruits to protect their valuable seed contents. Comparatively smaller fruits were found in species that continually experience frequent disturbance by fire, while both small and large fruits were found among species subjected to both short and long fire intervals. In the latter case where a broad range of fire intervals is possible, some species have adopted a strategy of producing small seeds that provide superior colonisation ability in disturbed conditions, while other species have adopted a strategy of producing large seeds which are more competitive during longer intervals between disturbance by fire. Only when taxonomic membership at the subgeneric level was accounted for in analyses across all species, did a significant relationship emerge between fruit size and rainfall independently of fire interval and plant height; comparatively larger fruits were found in species experiencing lower average annual rainfall in the subgenera Eucalyptus and Symphyomyrtus. In contrast to previous studies, larger fruits were found only in short species, while small fruits were found in both short and tall species. Many short species have adopted a strategy of protecting their seeds from high fire intensity by producing larger fruit. Since tall species can elevate their fruit far above high fire intensity, they make considerable energy savings by producing smaller fruit. It remains an open question as to why small fruit size occurs in some short species, but we suggest that these species may invest more heavily in vegetative regrowth after fire than in re‐establishment by seed.

Dinucleotide microsatellites fromEucalyptus sieberi: inheritance, diversity, and improved scoring of single-base differences

Eight dinucleotide microsatellites were developed in Eucalyptus sieberi L. Johnson (silvertop ash), a member of the subgenus Eucalyptus. Transfer of six of these to the subgenus Symphyomyrtus and their Mendelian inheritance are demonstrated using a full-sib cross in Eucalyptus nitens. Genetic diversity parameters are presented for the eight loci based on a sample of 100 old-growth E. sieberi trees from a single natural stand. One locus, Es266, had an atypically high fixation index, and significantly deviated from Hardy-Weinberg equilibrium genotypic proportions, indicating the likely presence of null alleles. Two of the loci, Es076 and Es140, had many alleles that differed in size by only a single base pair, possibly because of short poly(A) or poly(T) stretches in their flanking regions. These two loci were by far the most polymorphic, but were difficult to score reliably on a capillary DNA sequencer. Reliability of scoring of these two one-base microsatellite loci was markedly improved by the incorporation of internal reference alleles into each sample analysed.

English

Johnson, L.A.S., & Hill, K.D. (National Herbarium of New South Wales, Royal Botanic Gardens, Sydney, Australia 2000) 1999. Systematic studies in the eucalypts. 9. A review of series Sociales (Eucalyptus subgenus Symphyomyrtus, Section Bisectaria, Myrtaceae). Telopea 8(2): 165–218. A review of Eucalyptus series Sociales is presented, with a classification and enumeration of species recognised. A total of 30 species is recognised, 10 of them described here as new (E. delicata, E. dolichocera, E. hypolaena, E. intrasilvatica, E. luculenta, E. moderata, E. optima, E. sublucida E. ultima and E. vokesensis). New subspecies are recognised in E. oleosa (subsp. ampliata, corvina, cylindroidea, repleta, victima and wylieana) and E. transcontinentalis (subsp. semivestita). Revised circumscriptions are discussed for E. flocktoniae and E. grasbyi, and lectotypifications proposed for E. kochii, E. socialis and E. oleosa var. glauca (the latter as a synonym of E. transcontinentalis). Distributions of all taxa are mapped, and new and revised taxa are illustrated.

English

Hill, K.D. and Johnson, L.A.S. (National Herbarium of New South Wales, Royal Botanic Gardens, Sydney, Australia 2000) 1998. Systematic studies in the eucalypts. 8. A review of the Eudesmioid eucalypts, Eucalyptus subgenus Eudesmia (Myrtaceae). Telopea 7(4): 375–414. A revision of Eucalyptus subgenus Eudesmia is presented. A formal combination is made for subgenus Eudesmia. 22 species are included, three of them described as new (Eucalyptus pallida, E. selachiana, E. conveniens), with one new subspecies (E. ebbanoensis subsp. glauciramula). Long-standing misapplication of the name E. tetragona is corrected, the name E. pleurocarpa Schauer reinstated from synonymy, and a lectotype is designated for E. phoenicea. Relationships within the group are discussed, and an infrageneric classification is presented, with keys to subgroupings and species.