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Gregory J. Jordan - One of the best experts on this subject based on the ideXlab platform.
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Evidence of Pleistocene plant extinction and diversity from Regatta Point, western Tasmania, Australia
Botanical Journal of the Linnean Society, 1997Co-Authors: Gregory J. JordanAbstract:The Early Pleistocene Regatta Point sediments contain macrofossils that suggest that generic and specific rainforest diversity was higher in the region that it is today both locally and regionally, but the diversity was probably lower than it was for most of the Tertiary. The sediments contain extinct species of conifers and angiosperms which have closest living relatives in a wide range of environments, mainly wet forests of warmer areas than western Tasmania, but also relatively cool and dry areas. Simple models of climatically driven extinction explain these extinctions poorly. It is more likely that there was a wide range of causes of extinctions. New species,Acacia bulbosa, Rubus nebuloides, Quintinia tasmanensis, Oxylobium pungens, Laurophyllum australumandMyrtaceaephyllum pleistocenicum, are described.
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Macrofossil evidence for Quaternary plant extinction and vegetation change in western Tasmania
1992Co-Authors: Gregory J. JordanAbstract:Macrofossils from Pleistocene sediments in western Tasmania are investigated in order to reconstruct vegetation from this critical period. in the history of Australia's vegetation. The microfossil record shows that many taxa. notably the common Tertiary taxa Nothofagus subgenus Brassospora. Araucariaceae. Dacrycarpus and Dacrydium. were present in western Tasmania during the Latest Pliocene or Earliest Pleistocene but are now extinct from Tasmania. Most of these taxa are likely to have been rainforest species, but some may have been from sclerophyll vegetation (e.g. Beauprea). A few of these persisted into the Early-Middle Pleistocene and only Quintinia to the Late Pleistocene. Macrofossils of now globally and regionally extinct taxa occur in the Early Middle Pleistocene Regatta Point sediments. Most of these extinct taxa are not distinct in the relatively good microfossil record of that area. Some clearly sclerophyllous taxa have become extinct e.g. Banksia strahanensis and Oxylobium sp. nov. Rainforest taxa no longer occurring in Tasmania have affinities with species from temperate New Zealand (e.g. Quintinia sp. nov.), montane north-eastern New South Wales and Queensland (e.g. Rubus cf. moorei forma glabra, aff. Austromyrtus and Laurophyllum sp.). Macrofossils of only one extinct species occur in sediments younger than Regatta Point: Banksia kingii from the Late Pleistocene Melaleuca Inlet sediments. Local climatic and vegetation reconstructions for the times of deposition are made -for the Regatta Point, the middle Pleistocene Regency and the late Pleistocene Melaleuca Inlet sediments based on floristics. Vegetation reconsttuctions include analysis of diversity using both floristics and a modified rarefaction method. Both climatic and vegetation reconstructions are interpreted in terms of taphonomic studies both in this work and elsewhere. Regression modelling of the leaf size of N. cunninghamii from modern forest floor litter against BIOCLIM synthetic climatic parameters indicates that leaf length is well correlated to temperature of the growing season and palaeo-temperatures are estimated for the fossil floras. The extinctions are interpreted in terms of the climatic and vegetation reconstructions of the sites and broader scale knowledge of late Cenozoic climate, vegetation and glacial history. Many Tertiary taxa survived the climatic disruptions of the Early Pleistocene, but probably become extinct directly or indirectly due to the glaciations of the Middle Pleistocene. Rainforest diversity is lower now than during the Early Pleistocene, but the results are ambiguous for overall diversity. There is no reason to suspect that Tasmania could not support more diverse rainforest under modern conditions.
Gregory T Chandler - One of the best experts on this subject based on the ideXlab platform.
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Oxylobium gastrolobium fabaceae mirbelieae conundrum further studies using molecular data and a reappraisal of morphological characters
Plant Species Biology, 2003Co-Authors: Gregory T Chandler, Randall J Bayer, Simon GilmoreAbstract:A molecular phylogeny of Oxylobium , Gastrolobium and related genera, including Brachysema , Jansonia , Nemcia and Podolobium, is presented. The study was conducted using five molecular regions and 48 taxa, utilizing chloroplast DNA (the trn K 5¢¢ intron, psb A/ trn H intergenic spacer, trn L intron and adjacent trn L/ trn F intergenic spacer) and nuclear ribosomal DNA (ETS and ITS) markers. Oxylobium is shown to be polyphyletic, while Gastrolobium is paraphyletic, containing within it the genera Brachysema , Jansonia and Nemcia , as well as Oxylobium lineare . This concurs with a previous molecular analysis and the results of the two analyses are compared. Morphological traits, such as subtending bracts, ovule number and fluoroacetate content, are shown to be homoplastic and suites of characters for defining the different genera using different morphological characters are presented. Our results support a recent monograph that expands Gastrolobium to include Brachysema , Jansonia , Nemcia and Oxylobium lineare . This revision leaves Oxylobium and Podolobium occurring exclusively in eastern Australia, while Gastrolobium occurs almost exclusively in south-western Australia, with only two species, G. brevipes and G. grandiflorum , occurring outside this area.
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A molecular phylogeny of the endemic Australian genus Gastrolobium (Fabaceae: Mirbelieae) and allied genera using chloroplast and nuclear markers
American journal of botany, 2001Co-Authors: Gregory T Chandler, Randall J Bayer, Michael D. CrispAbstract:Gastrolobium (Fabaceae: Mirbelieae) is an endemic Australian genus that produces toxic sodium monofluoroacetate. A phylogenetic reconstruction of Gastrolobium and the related genera Brachysema, Callistachys, Jansonia, Nemcia, Oxylobium,and Podolobium is presented, using sequence data from three regions—the psbA-trnH intergenic spacer and the trnK 59 intron from chloroplast DNA and the 39 end of the external transcribed spacer (ETS) from nuclear ribosomal DNA. Gastrolobium is shown to be paraphyletic, with Brachysema, Jansonia, Nemcia,and Oxylobium linearenesting within it, and Nemcia is shown to be polyphyletic within Gastrolobium. Past key morphological characters, such as fluoroacetate content and characters associated with pollination syndrome, are shown to be homoplastic, with fluoroacetate possibly a plesiomorphic condition lost in more derived species. Podolobium is also shown to be polyphyletic, with the P. ilicifolium group sister to Gastrolobium and the P. alpestre group sister to Callistachys, a member of the Oxylobium group. It is recommended that Gastrolobiumbe expanded to include Brachysema, Jansonia, Nemcia,and Oxylobium lineare, while further work is required to test the sister-group relationship between Podolobium s.s. (sensu stricto) and Gastrolobium.
Michael D. Crisp - One of the best experts on this subject based on the ideXlab platform.
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Molecular Evidence for Definition of Genera in the Oxylobium Group (Fabaceae: Mirbelieae)
Systematic Botany, 2009Co-Authors: Michael D. Crisp, Lyn G. CookAbstract:The circumscription of Oxylobium and related genera has been problematic for nearly 200 years. Traditional definitions of genera in the group have relied on morphological features of the leaves, flower, and fruit that overlap extensively between genera. Therefore sequences of cpDNA (trnL-F intron and spacer) and nrDNA (ITS) were used to estimate the phylogeny of the group in an attempt to redefine the genera as monophyletic groups. Oxylobium sens. str. was found to be a well supported clade in both data sets, with the inclusion of Mirbelia oxylobioides. No other genus in the group was supported by these data, except Gastrolobium sens. lat. Some species groups within Chorizema, Mirbelia, and Podolobium were supported but relationships among these, Oxylobium and Gastrolobium differed significantly between the chloroplast and nuclear data sets. No group supported by the molecular data had a morphological synapomorphy, not even Oxylobium or Gastrolobium. Therefore it may be necessary to adopt a much broader generic concept in this group than has been done previously. Incongruence between the two molecular data sets, and very short internal basal branches in both, suggest a rapid early radiation in this group, possibly combined with hybridization and lineage sorting.
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A molecular phylogeny of the endemic Australian genus Gastrolobium (Fabaceae: Mirbelieae) and allied genera using chloroplast and nuclear markers
American journal of botany, 2001Co-Authors: Gregory T Chandler, Randall J Bayer, Michael D. CrispAbstract:Gastrolobium (Fabaceae: Mirbelieae) is an endemic Australian genus that produces toxic sodium monofluoroacetate. A phylogenetic reconstruction of Gastrolobium and the related genera Brachysema, Callistachys, Jansonia, Nemcia, Oxylobium,and Podolobium is presented, using sequence data from three regions—the psbA-trnH intergenic spacer and the trnK 59 intron from chloroplast DNA and the 39 end of the external transcribed spacer (ETS) from nuclear ribosomal DNA. Gastrolobium is shown to be paraphyletic, with Brachysema, Jansonia, Nemcia,and Oxylobium linearenesting within it, and Nemcia is shown to be polyphyletic within Gastrolobium. Past key morphological characters, such as fluoroacetate content and characters associated with pollination syndrome, are shown to be homoplastic, with fluoroacetate possibly a plesiomorphic condition lost in more derived species. Podolobium is also shown to be polyphyletic, with the P. ilicifolium group sister to Gastrolobium and the P. alpestre group sister to Callistachys, a member of the Oxylobium group. It is recommended that Gastrolobiumbe expanded to include Brachysema, Jansonia, Nemcia,and Oxylobium lineare, while further work is required to test the sister-group relationship between Podolobium s.s. (sensu stricto) and Gastrolobium.
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Phylogeny and embyro sac evolution in the endemic Australasian Papilionoid tribes Mirbelieae and Bossiaeeae
2001Co-Authors: Michael D. Crisp, Lynette Gai CookAbstract:The Mirbelieae and Bossiaeeae are related tribes restricted to the Australian region. This study analyses the most comprehensive sample to date of DNA sequences (trnL intron and ITS) from both tribes. Monophyly of the Mirbelieae + Bossiaeeae with respect to putatively related tribes is supported, albeit weakly. Bossiaeeae is a strongly supported clade but nested within a paraphyletic Mirbelieae. There is evidence for alternative groupings based on embryo sac morphology and development. Bossiaeeae could be expanded to include the Daviesia group of Mirbelieae, with which it shares giant antipodals, but stronger evidence is needed for monophyly of this group. Mirbelieae could be reduced to the clade comprising Isotropis and the Mirbelia group, which share absence of antipodals. The Mirbelia group appears to have rapidly diversified into many lineages that do not cluster to form well defined genera. Several genera currently recognised in this group are not supported by the molecular data. To achieve consistency of generic delimitation within the tribes, this group should perhaps be treated as a single genus by expanding Pultenaea to include all genera currently recognised in the Mirbelia group. Introduction The Mirbelieae and Bossiaeeae are two papilionoid tribes endemic to Australia and New Guinea. Most species in these tribes are ericoid shrubs with yellow and red (‘egg and bacon’) flowers. They are conspicuous, sometimes dominant, understorey members of sclerophyll communities (heathland and eucalypt-dominated woodland and forest), on poor soils of the south-west, south and east coast of Australia. The Bossiaeeae includes 6 genera and about 77 species (Ross and Crisp, in press) and the Mirbelieae includes about 670 species in 25 genera (Crisp et al., in press), although recently four genera were combined into a much enlarged Gastrolobium (Chandler et al., 2002). The definition and relationships of both tribes have been problematic. After a long history of placement of its genera in the Podalyrieae, Mirbelieae was recognised in its present circumscription by Polhill (1981). Bossiaeeae was segregated from Genisteae (Hutchinson, 1964), and included the Bossiaea and Templetonia groups of Australian genera (Polhill, 1976, 1981). Subsequently, the Templetonia group was 253 Crisp, M.D. and Cook, L.G. (2003). Phylogeny and embryo sac evolution in the endemic Australasian Papilionoid tribes Mirbelieae and Bossiaeeae. In: B.B. Klitgaard and A. Bruneau (editors). Advances in Legume Systematics, part 10, Higher Level Systematics, pp 253–268. Royal Botanic Gardens, Kew. * author for correspondence: Mike.Crisp@anu.edu.au found to group strongly with the neotropical tribe Brongniartieae, according to morphology (Crisp and Weston, 1987), nuclear ribosomal DNA (Crisp et al., 2000; Thompson et al., 2001) and chloroplast DNA (Kajita et al., 2001). When restricted to include only the Bossiaea group, the Bossiaeeae appeared to form a clade with the Mirbelieae which was not closely related to either the Brongniartieae or the genistoid tribes (Crisp and Weston, 1987; Crisp et al., 2000; Kajita et al., 2001). Although Mirbelieae + Bossiaeeae was monophyletic according to morphology (Crisp and Weston, 1987) and ITS sequences (Crisp et al., 2000), support for this clade has been weak. Within the Oxylobium and Pultenaea groups of Mirbelieae, high morphological diversity has been the basis for recognising about 450 species in 20 genera, yet generic delimitation has continued to be problematic (Sands, 1975; Crisp and Weston, 1987, 1995). All taxa in the Mirbelieae and Bossiaeeae which have been investigated have unusual embryology (Cameron and Prakash, 1990, 1994) in comparison with most other legumes. Typical embryology in the legumes is Polygonum-type which produces an 8-nucleate embryo sac (Prakash, 1987). Some taxa in the Mirbelieae and Bossiaeeae have Polygonum-type development but produce greatly enlarged antipodal cells, possibly serving a role in nutrition for the embryo (Cameron and Prakash, 1990). Hereafter this embryology is termed the ‘giant antipodals’ (GA) type. GAtype taxa comprise the Bossiaeeae and the Daviesia group (Daviesia, Erichsenia, Gompholobium, Sphaerolobium and Viminaria) of Mirbelieae (Crisp and Weston, 1995). The remaining taxa within Mirbelieae have a more unusual type of development (Cameron and Prakash, 1994). It resembles Oenothera-type (Willemse and van Went, 1984; Reiser and Fischer, 1993) embryology but megagametogenesis involves three mitoses (not two) to produce five nuclei (not four). No antipodals are produced and polarity is reversed during megasporogenesis, so that the micropylar (not chalazal) megaspore is functional and any to all megaspores (not just the chalazal) undergo mitosis to produce partially or fully developed embryo sacs. Cameron and Prakash (1994) called this development ‘Mirbelia’ type after one genus in which it is found but here we refer to it by the descriptive term ‘no antipodals’ (NA) type. There are two variants of the NA type. One is as described above and here is termed the ‘fivenucleate embryo sac’ (FNES) type. The other NA type, called ‘Jacksonia’ type by Cameron and Prakash (1994), produces multiple archesporial cells and embryo sacs, some of which may be aposporous although apomixis has not been confirmed. This form is here termed the ‘multiple embryo sac’ (MES) type. Embryology is not known to vary within GA-type genera of the Mirbelieae and Bossiaeeae. However, some NA-type genera (Dillwynia, Jacksonia and Mirbelia) have MES type and FNES type in different species (Cameron and Prakash, 1994). Above genus level, the phylogenetic distribution of embryology types is unclear. Different studies have found each of the GA and NA embryological groups within Mirbelieae and Bossiaeeae to be either monophyletic or paraphyletic. A recent analysis using ITS sequences found the GA and NA embryological groups to be monophyletic sister taxa, whereas Mirbelieae and Bossiaeeae were paraphyletic (Crisp et al., 2000). Giant antipodals also have been reported from two species of Indigofera (Cameron and Prakash, 1990, 1994). Given that Indigofereae appears not to group with Mirbelieae/Bossiaeeae (Crisp et al., 2000; Kajita et al., 2001), giant antipodals may not be homologous in these two tribal groups. This study aimed to test whether the Mirbelieae and Bossiaeeae are monophyletic sister taxa, or whether alternative groupings based on embryo sac type are supported. Within these tribes, relationships among genera were investigated and compared with existing classification. This study differed from previous phylogenetic analyses of these tribes by sampling comprehensively at genus level using DNA sequences from the nuclear and chloroplast genomes. Advances in Legume Systematics 10
Randall J Bayer - One of the best experts on this subject based on the ideXlab platform.
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Oxylobium gastrolobium fabaceae mirbelieae conundrum further studies using molecular data and a reappraisal of morphological characters
Plant Species Biology, 2003Co-Authors: Gregory T Chandler, Randall J Bayer, Simon GilmoreAbstract:A molecular phylogeny of Oxylobium , Gastrolobium and related genera, including Brachysema , Jansonia , Nemcia and Podolobium, is presented. The study was conducted using five molecular regions and 48 taxa, utilizing chloroplast DNA (the trn K 5¢¢ intron, psb A/ trn H intergenic spacer, trn L intron and adjacent trn L/ trn F intergenic spacer) and nuclear ribosomal DNA (ETS and ITS) markers. Oxylobium is shown to be polyphyletic, while Gastrolobium is paraphyletic, containing within it the genera Brachysema , Jansonia and Nemcia , as well as Oxylobium lineare . This concurs with a previous molecular analysis and the results of the two analyses are compared. Morphological traits, such as subtending bracts, ovule number and fluoroacetate content, are shown to be homoplastic and suites of characters for defining the different genera using different morphological characters are presented. Our results support a recent monograph that expands Gastrolobium to include Brachysema , Jansonia , Nemcia and Oxylobium lineare . This revision leaves Oxylobium and Podolobium occurring exclusively in eastern Australia, while Gastrolobium occurs almost exclusively in south-western Australia, with only two species, G. brevipes and G. grandiflorum , occurring outside this area.
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A molecular phylogeny of the endemic Australian genus Gastrolobium (Fabaceae: Mirbelieae) and allied genera using chloroplast and nuclear markers
American journal of botany, 2001Co-Authors: Gregory T Chandler, Randall J Bayer, Michael D. CrispAbstract:Gastrolobium (Fabaceae: Mirbelieae) is an endemic Australian genus that produces toxic sodium monofluoroacetate. A phylogenetic reconstruction of Gastrolobium and the related genera Brachysema, Callistachys, Jansonia, Nemcia, Oxylobium,and Podolobium is presented, using sequence data from three regions—the psbA-trnH intergenic spacer and the trnK 59 intron from chloroplast DNA and the 39 end of the external transcribed spacer (ETS) from nuclear ribosomal DNA. Gastrolobium is shown to be paraphyletic, with Brachysema, Jansonia, Nemcia,and Oxylobium linearenesting within it, and Nemcia is shown to be polyphyletic within Gastrolobium. Past key morphological characters, such as fluoroacetate content and characters associated with pollination syndrome, are shown to be homoplastic, with fluoroacetate possibly a plesiomorphic condition lost in more derived species. Podolobium is also shown to be polyphyletic, with the P. ilicifolium group sister to Gastrolobium and the P. alpestre group sister to Callistachys, a member of the Oxylobium group. It is recommended that Gastrolobiumbe expanded to include Brachysema, Jansonia, Nemcia,and Oxylobium lineare, while further work is required to test the sister-group relationship between Podolobium s.s. (sensu stricto) and Gastrolobium.
John Brockwell - One of the best experts on this subject based on the ideXlab platform.
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Symbiotic response of the eight host plants to rhizobial strains originally collected from the same host species, and to the broadly effective Acacia control strain (WG; filled circles).
2013Co-Authors: Peter H. Thrall, Anna-liisa Laine, Linda M. Broadhurst, David J. Bagnall, John BrockwellAbstract:The solid line at 1 on the y-axis indicates the growth response level where the host did not gain or lose anything from the rhizobial interaction relative to the N− control treatment. Symbiotic response values 1 indicate a positive effect of inoculation. The dashed line is the average symbiotic response to all rhizobial strains. Error bars are based on standard errors of means (if not visible, they are smaller than the symbols). BOS = Bossiaea foliosa, DAV = Daviesia ulicifolia, DIL = Dillwynia retorta, GOO = Goodia lotifolia, HAR = Hardenbergia violacea, IND = Indigofera australis, OXY = Oxylobium ellipticum, and POD = Podolobium ilicifolium. Note the different y-axis scales between figure panels.
