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1
Miller, Ben P., David R. Symons e Matthew D. Barrett. "Persistence of rare species depends on rare events: demography, fire response and phenology of two plant species endemic to a semiarid Banded Iron Formation range". Australian Journal of Botany 67, n. 3 (2019): 268. http://dx.doi.org/10.1071/bt18214.
Testo completoAbstract (sommario):
The association of rare plant species and Banded Iron Formation (BIF) ranges in semiarid Western Australia is a noted phenomenon. These ranges are also a focus of iron ore exploration and mining. Decisions and planning required for development, conservation and management resulting from this interest, often consider translocation of these threatened species. Nonetheless, little is known about the ecology of BIF-endemic species to support any such decisions. We assessed population structure, patterns of growth, mortality, recruitment, reproduction and in situ seedbank persistence for two declared rare flora species. The shrub Darwinia masonii, and sedge Lepidosperma gibsonii are endemic to an area <40 km2 on the south-western boundary of the Australian arid zone. Both species were found to be long lived and slow growing, with evidence for reliance on rare events such as fire, and high rainfall years, including, for some processes, consecutive high rainfall years for growth, reproduction and recruitment. Retrieval and germination of seed batches shows that both species’ seedbanks are long-lived, with seasonal dormancy cycling. This, together with the ability of mature plants to survive through years not supporting growth, and, for L. gibsonii, to resprout after fire, are key mechanism for persistence in this unpredictable and low rainfall environment.
2
Kennedy, J., e G. Weste. "Vegetation Changes Associated With Invasion by Phytophthora cinnamomi on Monitored Sites in the Grampians, Western Australia". Australian Journal of Botany 34, n. 3 (1986): 251. http://dx.doi.org/10.1071/bt9860251.
Testo completoAbstract (sommario):
The effects of invasion by Phytophthora cinnamomi were measured on sites representing the larger forest regions of the Grampians. Changes were obvious at first, with the death of more than 50% of the species including large plants such as Xanthorrhoea australis, but soon became dificult to detect as susceptible species were replaced by field-resistant graminoids. Reductions were assessed in species heterogeneity and plant density during 1976, at the onset of disease and from 1977 to 1984. Susceptible species disappeared from infested forest and no re-emergence was observed. Less-susceptible plants such as some Euca/yptus spp. declined in number, regeneration and size, due to deaths or dieback of the branches. Reductions in tree canopy and the loss of structural dominants of the understorey caused changes in the flora which are likely to persist. The survival of rare, susceptible endemic species may be endangered. On dry, steep slopes the dead plants were not replaced and the amount of bare ground increased causing erosion of the soil surface. Some graminoid species increased in abundance on level, infested sites, resulting in a different species composition but with both species heterogeneity and plant density numerically similar to the previous flora.
3
Cox, Brad. "Granite Outcrops Symposium". Pacific Conservation Biology 4, n. 3 (1998): 271. http://dx.doi.org/10.1071/pc98271a.
Testo completoAbstract (sommario):
Western Australia is a flat landscape. Granite outcrops are one of the few features that rise above the terrain. This makes them unique landmarks for people, and islands for plants and animals. They are highly significant in terms of their geological, biological and cultural values. They contain some of the world's oldest rocks, are an important source of water, often contain aboriginal heritage sites and are refuges for many rare and endangered flora and fauna.
4
Touchell, DH, KW Dixon e B. Tan. "Cryopreservation of Shoot-Tips of Grevillea scapigera (Proteaceae): a Rare and Endangered Plant From Western Australia". Australian Journal of Botany 40, n. 3 (1992): 305. http://dx.doi.org/10.1071/bt9920305.
Testo completoAbstract (sommario):
Cryopreservation of leaf, petiole, stem pieces and shoot-tips was investigated as a means for long-term maintenance of germplasm of the rare and endangered species, Grevillea scapigera A.S. George. Crypreservation was only achieved using shoot-tips or axillary buds and a slow-cooling regime with the aid of an improvised freezing device. The highest survival of thawed explants (20%) was obtained with 4-week-old in vitro shoot-tips cultured for 48 h in a prefreezing liquid culture medium supplemented with 5% dimethylsulfoxide. The pretreated shoot-tips were frozen in a liquid medium containing 10% dimethylsulfoxide cooled at a rate of 0.5°C/min to -40°C and held at this temperature for 30 min before being plunged into liquid nitrogen. Shoot-tips that survived the freeze-thaw cycle produced callus followed by shoot production 22 weeks after thawing. All shoots regenerated from thawed tissues and transferred to soil appeared phenotypically identical to untreated control shoots and plants. Rapid methods for assessing post-thaw tissue viability and explant recovery using triphenyltetrazolium chloride were tried but these methods were inadequate for determining the capacity of thawed tissues to recover from freeze damage.
5
Briggs, BG, LAS Johnson e SL Krauss. "The species of Alexgeorgea, a Western Australian genus of the restionaceae". Australian Systematic Botany 3, n. 4 (1990): 751. http://dx.doi.org/10.1071/sb9900751.
Testo completoAbstract (sommario):
The three species of Alexgeorgea Carlquist are revised, including A. ganopoda L. Johnson & B. Briggs, a newly described rare species of the Mt Frankland–Bow River region of the south-west of Western Australia.
6
Olde, Peter. "Grevillea pieroniae Olde (Proteaceae: Grevilleoideae: Hakeinae), a rare new species in the Triloba Group from the Stirling Range, Western Australia, and a short history of the group." Telopea 23 (2020): 227–35. http://dx.doi.org/10.7751/telopea14783.
Testo completoAbstract (sommario):
Twenty-one Grevillea species currently comprise the Triloba Group sensu Flora of Australia, or Group 1 sensu The Grevillea Book. All species except the transcontinental species G. anethifolia R.Br. are distributed in southwest Western Australia. Grevillea pieroniae Olde, herein described, is currently treated as Grevillea sp. Stirling Range (D.J. McGillivray 3488 & A.S. George) by the Western Australian Herbarium. It has some affinity with Grevillea anethifolia through shared possession of similar truncate-conical to cylindrical pollen-presenters. Grevillea pieroniae is a rare species that is potentially threatened by Phytophthora cinnamomi, fire frequency, a drying climate, as well as grazing by feral and native herbivores, so requires careful assessment and ongoing monitoring. A short history of the Triloba Group is provided to give context to Grevillea pieroniae and as precursor to other related species soon to be recognised.
7
Pierce, Nuri B., e Michael G. Simpson. "Polyaperturate pollen types and ratios of heteromorphism in the monocot genus Conostylis (Haemodoraceae)". Australian Systematic Botany 22, n. 1 (2009): 16. http://dx.doi.org/10.1071/sb08040.
Testo completoAbstract (sommario):
Pollen aperture heteromorphism (variation of aperture number in pollen grains within each flower and in all plants of a taxon) is described in the diverse monocot genus Conostylis R.Br. (Haemodoraceae) and that of related genera, all endemic to Western Australia. We report results of pollen observations from 153 specimens. In Conostylis, aperture number varies greatly, with biporate, triporate, tetraporate and polyporate pollen present, features considered rare and possibly developmentally significant for monocots. Pollen aperture types and their ratios in this genus are stable and consistent within species and subspecies groupings and phylogenetically informative.
8
Walker, E., M. Byrne, B. Macdonald, D. Nicolle e J. McComb. "Clonality and hybrid origin of the rare Eucalyptus bennettiae (Myrtaceae) in Western Australia". Australian Journal of Botany 57, n. 3 (2009): 180. http://dx.doi.org/10.1071/bt08148.
Testo completoAbstract (sommario):
Clonality and hybrid origin influence the conservation status of rare and restricted species. Eucalyptus bennettiae Carr & Carr is a rare species known only from a few individuals that may be clonal and may have arisen through hybridisation between other co-occurring species. The hybrid status and clonality of E. bennettiae was investigated with analysis of microsatellite variation in E. bennettiae compared with its putative parents, E. lehmannii subsp. parallela, E. sporadica and E. astringens subsp. redacta, identified through morphological characteristics. Analysis of microsatellite variation revealed clonality with one individual present at each location, and additivity of alleles and no unique alleles in E. bennettiae compared with two of the putative parents, E. lehmannii subsp. parallela and E. sporadica. In addition, E. bennettiae displayed intermediacy in species relationships and measures of relatedness, and assignment tests showed mixed ancestry in relation to these species but not the third putative parent, E. astringens subsp. redacta. These findings confirm that E. bennettiae is a hybrid and evaluation of the taxon for conservation protection shows that it does not satisfy the criteria for listing as a threatened species.
9
Butcher, Ryonen. "New taxa of 'leafless' Tetratheca (Elaeocarpaceae, formerly Tremandraceae) from Western Australia." Australian Systematic Botany 20, n. 2 (2007): 139. http://dx.doi.org/10.1071/sb06015.
Testo completoAbstract (sommario):
The relationships among rare ‘leafless’ species of Tetratheca Sm. occurring on banded ironstone ranges near Koolyanobbing, Western Australia, and allied, unclassified, populations from Eneabba, Newdegate and the Die Hardy Range have been assessed by molecular characters. These findings, in conjunction with morphological investigations, have identified a new species and two new subspecies from within the ‘T. aphylla group’ and these are formally described here. Tetratheca nephelioides R.Butcher, is geographically restricted to the Eneabba area and has close morphological affinity to T. aphylla F.Muell. Tetratheca aphylla subsp. megacarpa R.Butcher, is restricted to the Newdegate area, some 300 km south of the only known populations of T. aphylla subsp. aphylla in the Helena and Aurora Range. Tetratheca paynterae Alford subsp. cremnobata R.Butcher is restricted to the Die Hardy Range, c. 10 km north-east of the only known population of T. paynterae subsp. paynterae at ‘Windarling’. All of these taxa are recognised as Declared Rare Flora. In the process of updating the existing key to ‘leafless’ species of Tetratheca to include these new taxa, two additional new species were identified from within collections of T. nuda Lindl. These are described here as T. angulata R.Butcher and T. applanata R.Butcher. Images and distribution maps for all taxa are provided.
10
Li, C. X., Hua Li, K. Sivasithamparam, T. D. Fu, Y. C. Li, S. Y. Liu e M. J. Barbetti. "Expression of field resistance under Western Australian conditions to Sclerotinia sclerotiorum in Chinese and Australian Brassica napus and Brassica juncea germplasm and its relation with stem diameter". Australian Journal of Agricultural Research 57, n. 10 (2006): 1131. http://dx.doi.org/10.1071/ar06066.
Testo completoAbstract (sommario):
Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, has become one of the most serious disease problems in oilseed rape-growing areas in Australia. Sources of resistance to this disease have been sought worldwide. In this study, germplasm comprising 42 Brassica napus and 12 Brassica juncea accessions from China and Australia, was screened for resistance to Sclerotinia stem rot under Western Australian field conditions. Resistance was confirmed in some germplasm from China and new sources of resistance were identified in germplasm from Australia. Furthermore, our study found that the severity of stem lesions was related to stem diameter and percentage of the host plants that were dead. It was evident that both stem lesion length and percentage of plant death were at the lowest level when the stem diameter was approximately 10 mm. Smaller or greater stem diameter resulted both in increased stem lesion length and plant death. Stem diameter may be a useful parameter in breeding cultivars of oilseed Brassicas with Sclerotinia resistance.
11
Hopper, Stephen D., e Nathan K. McQuoid. "Two new rare species and a new hybrid in Eucalyptus series Tetrapterae (Myrtaceae) from southern coastal Western Australia". Australian Systematic Botany 22, n. 3 (2009): 180. http://dx.doi.org/10.1071/sb06034.
Testo completoAbstract (sommario):
Three new rare taxa allied to the conspicuous, common four-winged mallee (Eucalyptus tetraptera Turcz.) are described. E. sweedmaniana is a large-leaved and prostrate coastal mallee known only from Mount Arid, Western Australia. E. brandiana, a non-lignotuberous mallet, occupies spongolite hilltops and escarpments near the Fitzgerald River Inlet in Fitzgerald River National Park, Western Australia. A single hybrid mallet, E. arborella × brandiana, is described from the type locality of E. brandiana. Both new species and the new hybrid show potential for horticultural use, given their compact habit, large leaves and conspicuous red floral hypanthia and fruits. E. arborella × brandiana and E. brandiana are particularly at risk, being highly localised endemics that are killed by fire.
12
Ladd, P. G., C. J. Yates, R. Dillon e R. Palmer. "Pollination ecology of Tetratheca species from isolated, arid habitats (Banded Iron Formations) in Western Australia". Australian Journal of Botany 67, n. 3 (2019): 248. http://dx.doi.org/10.1071/bt18249.
Testo completoAbstract (sommario):
Pollination and reproductive ecology of arid zone species in Australia are neglected topics. This is particularly true of rare species, some of which are threatened by mining operations. The bee community at Windarling Range in southern Western Australia and the pollination ecology of four rare Tetratheca taxa with distributions restricted to Banded Iron Formation inselbergs in the arid south-west were examined in winter and spring to understand if pollination rate was affecting the reproductive ecology of the plants. The bee fauna on the Windarling Range was sampled using coloured pan traps at three landscape positions of ridge (where Tetratheca paynterae subsp. paynterae occurs), slope and flats and the insect visitors to T. paynterae subsp. paynterae were quantified by direct observation. The bee fauna varied over the two years with average richness higher in 2010 than 2011 and was higher on the ridge compared with the slope and flats below the inselberg. The Tetratheca species are buzz pollinated and T. paynterae subsp. paynterae is only visited by a subsection of the bee fauna, mainly Lasioglossum species, which were shown to be relatively faithful to the species in terms of the pollen they carried. Flowering mainly occurs after the winter wet season, but may occur at other times when there has been substantial rain. This may not coincide with bee activity. In the winter flowers may be poorly serviced if maximum daytime temperatures are below 20°C. However, in spring when temperatures are higher the majority of flowers were pollinated and there was no significant difference in proportion of pollinated flowers between the four taxa examined. As T. paynterae is outcrossing the propensity for bees to attend few flowers on a visit to each plant, often on the outer part of the plant canopy, will likely ensure a high success rate for seed formation. High seed set in such an arid environment with few suitable sites for seedling establishment is essential so some propagules can find safe sites for establishment to maintain population numbers.
13
Orchard, A. E. "A revision of Cassinia (Asteraceae: Gnaphalieae) in Australia. 7. Cassinia subgenus Achromolaena". Australian Systematic Botany 30, n. 4 (2017): 337. http://dx.doi.org/10.1071/sb17033.
Testo completoAbstract (sommario):
The present paper completes a revision of the endemic Australian genus Cassinia R.Br. Cassinia subgenus Achromolaena comprises two sections, namely, section Achromolaena of seven species (C. laevis, C. arcuata, C. uncata, C. tenuifolia, C. collina, C. subtropica, and C. quinquefaria), and Cassinia section Siftonia, which contains two species (C. sifton and C. theodorii). Cassinia laevis is divided into western (C. laevis subsp. laevis) and eastern (C. laevis subsp. rosmarinifolia (A.Cunn.) Orchard, comb. et stat. nov.) taxa. Examination of the type of C. arcuata showed that this name is synonymous with C. paniculata, and applies to a relatively rare taxon with whitish capitula arranged in short erect compact panicles, and found in Western Australia, the midlands of South Australia, western Victoria and (formerly) south-western New South Wales. Furthermore, it belongs to section Achromolaena. The taxon with red to brown capitula, widespread throughout south-eastern Australia, which until now has been (incorrectly) known as C. arcuata (Sifton bush) is distinct, but lacks a published name. The name Cassinia sifton Orchard, sp. nov. is here proposed for this taxon. An unfortunate outcome of this discovery is that the sectional name Cassinia section Arcuatae, with C. arcuata as type, becomes synonymous with section Achromolaena. The new name Cassinia section Siftonia is proposed to accommodate Sifton bush (C. sifton) and its narrowly endemic sister species C. theodorii. A summary of the whole genus is provided, with keys to all taxa. Three former subspecies of C. macrocephala are raised to species rank (C. petrapendula (Orchard) Orchard, C. storyi (Orchard) Orchard, C. tenuis (Orchard) Orchard), and it is suggested that C. furtiva Orchard may be conspecific with C. straminea (Benth.) Orchard.
14
Crisp, Michael D., e Gregory T. Chandler. "Contributions Towards a Revision of Daviesia (Fabaceae: Mirbelieae). V. D. cardiophylla sens. lat." Australian Systematic Botany 10, n. 3 (1997): 321. http://dx.doi.org/10.1071/sb96015.
Testo completoAbstract (sommario):
Three new species, Daviesia cunderdin, D. euryloba and D. umbonata, are described from south-western Western Australia. The first is a recently discovered rare and endangered species from near the town after which it is named. The latter two are segregated from the widespread and variable species D. cardiophylla F.Muell. Full descriptions, illustrations, a distribution map and a key to all four species are presented.
15
Pegg, KG, RG Shivas, NY Moore e S. Bentley. "Characterization of a unique population of Fusarium oxysporum f.sp. cubense causing Fusarium wilt in Cavendish bananas at Carnarvon, Western Australia". Australian Journal of Agricultural Research 46, n. 1 (1995): 167. http://dx.doi.org/10.1071/ar9950167.
Testo completoAbstract (sommario):
A unique population of Fusarium oxysporum f. sp. cubense affecting Cavendish cv. Williams banana plants was characterized using vegetative compatibility, volatile production, RAPD-PCR analysis, pectic enzyme production and pathogenicity. The isolates were more like race 1 isolates than race 4 isolates, although they were capable of attacking Cavendish clones. The Carnarvon isolates did not belong to any of the vegetative compatibility groups (VCGs) known to occur in Australia or overseas; they belonged in the 'inodoraturn' volatile group; they had 29% genetic similarity to race 4 isolates and 76% similarity to race 1 isolates based on RAPD-PCR banding patterns; they belonged in the same pectic zymogram group as race 1 isolates and were virulent on 3-month-old Cavendish cv. Williams, Gros Michel and Pisang Gajih Merah plants in glasshouse tests.
16
Keighery, Greg J., Neil Gibson, Stephen van Leeuwen, Michael N. Lyons e Sue Patrick. "Biological survey and setting priorities for flora conservation in Western Australia". Australian Journal of Botany 55, n. 3 (2007): 308. http://dx.doi.org/10.1071/bt06102.
Testo completoAbstract (sommario):
Biological survey has been an integral component of conservation planning in Western Australia for >30 years, providing baseline data for reserve selection and the management of biodiversity at the genetic, species and community levels. Flora surveys are particularly important, given the diverse and poorly documented nature of the state’s vascular flora. Surveys have been conducted at the following four scales: regional, subregional, local and individual species. At all scales, flora surveys have provided detail on individual taxon distribution, have identified previously unknown or unrecognised taxa, have located presumed extinct taxa and have substantially contributed to information on the distribution of threatened flora. Regional-scale surveys normally involve multidisciplinary teams studying a broad selection of the biota. These combined plot-based data are used to develop a ‘classify-then-model’ approach to assessment of comprehensiveness, adequacy and representativeness of the regional conservation reserve system. These regional models describe the broad-scale patterning of common taxa but their utility in reflecting patterns in naturally rare or highly restricted taxa is uncertain. Results from recent surveys show poor correlations between floristic patterning and other components of the biota.
17
Bunn, Eric, e Kingsley W. Dixon. "In Vitro Propagation of the Rare and Endangered Grevillea scapigera (Proteaceae)". HortScience 27, n. 3 (marzo 1992): 261–62. http://dx.doi.org/10.21273/hortsci.27.3.261.
Testo completoAbstract (sommario):
Micropropagation, including adventitious shoot growth from leaf sections, was achieved for Grevillea scapigera (Proteaceae), a rare and endangered species from Western Australia. Shoot tips were initiated on filter paper supports with liquid WPM (Woody Plant Medium) and supplemented with 20 μm zeatin riboside and 2 μm GA3. Shoots were then incubated on WPM solidified with agar and supplemented with 5 μm kinetin and 0.5 μm BA, which produced an approximate 6-fold multiplication rate per month. Up to three adventitious shoots were induced from 0.7-cm2 leaf sections after 6 to 7 weeks on solid 1/2 MS (Murashige and Skoog) medium supplemented with 10 μm BA and 0.5 μm IBA. Shoots, 30 to 50 mm long, were rooted in vivo in a fogged glasshouse under 70% shade using a commerical rooting powder [IBA, 0.1% (w/w)] applied to the base of the shoots. Most (67%) of the shoots treated in this way rooted after 5 weeks. Established, rooted plants have been grown on under glasshouse conditions. Chemical names used: N6-[2-isopentenyl] adenine riboside (zeatin riboside); gibberellic acid (GA3); 6-furfurylaminopurine (kinetin); N-(phenylmethyl)-1H-purine-6-amine (BA); 1-H-indole-3-butyric acid (IBA).
18
Kaur, P., C. X. Li, M. J. Barbetti, M. P. You, H. Li e K. Sivasithamparam. "First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Brassica juncea in Australia". Plant Disease 92, n. 4 (aprile 2008): 650. http://dx.doi.org/10.1094/pdis-92-4-0650c.
Testo completoAbstract (sommario):
In Australia, Brassica juncea (L.) Czern & Coss (Indian mustard) has the potential as a more drought-tolerant oilseed crop than the B. napus L., with the first canola-quality B. juncea varieties released in Australia in 2006 and first sown for commercial production in 2007. Increased production of B. juncea is expected to result in the appearance of diseases previously unreported in Australia. In the spring of 2007 at the University of Western Australia field plots at Crawley (31.99°S, 115.82°E), Western Australia, plants of B. juncea genotypes from Australia and China had extensive stem colonization by powdery mildew at the end of the flowering period, with whitish patches ranging in size from 3 mm to 3 cm long. These patches coalesced to form a dense, white, powdery layer as they expanded. Pathogenicity was demonstrated by gently pressing infected stems containing abundant sporulation onto leaves of potted B. juncea seedlings of variety JM-18, incubating the plants in a moist chamber for 48 h, and then maintaining the plants in a controlled-environment room at 18/13°C for day/night. Signs of powdery mildew appeared at 7 days after inoculation, and by 10 days, it was well developed. Uninoculated control plants did not have powdery mildew. When symptomatic plants were examined, abundant conidia were typical of Erysiphe cruciferarum Opiz ex Junell, with cylindrical conidia borne singly or in short chains as described previously (2). Mycelia were amphigenous, in patches, and often spreading to become effused. Conidiophores were straight, foot cells were cylindrical, and conidia were mostly produced singly and measured 21.2 to 35.4 (mean 26.7 μm) × 8.8 to 15.9 μm (mean 11.9 μm) from measurements of 100 conidia. The spore size that we measured approximated what was found for E. cruciferarum (2) (30 to 40 × 12 to 16 μm), since we found 35 and 50% of spores falling within this range in terms of length and width, respectively. Conidia were, however, generally smaller in size than that reported on broccoli raab in California (1) (35 to 50 × 12 to 21 μm). We confirmed a length-to-width ratio greater than 2 as was found previously (1,2). Infected leaves showed signs of early senescence. While powdery mildew caused by E. cruciferarum is an important disease of B. juncea in India where yield losses as much as 17% have been reported (4), its potential impact in Australia is yet to be determined. To our knowledge, this is the first record of E. cruciferarum on B. juncea in Australia. In Western Australia, E. cruciferarum has been recorded on B. napus (oilseed rape) since 1986 and on B. napus L. var. napobrassica (L.) Reichenb. (swede) since 1971 (3). In other regions of Australia, it has been recorded on B. rapa in Queensland since 1913 and on B. napus (oilseed rape) in South Australia since 1973. References: (1) S. T. Koike and G. S. Saenz. Plant Dis. 81:1093, 1997. (2) T. J. Purnell and A. Sivanesan. No 251 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (3) R. G. Shivas. J. R. Soc. West. Aust. 72:1, 1989. (4) A. K. Shukla et al. Manual on Management of Rapeseed-Mustard Diseases. National Research Centre on Rapeseed-Mustard, Bharatpur, India, 2003.
19
Macphail, Michael K., e Robert S. Hill. "What was the vegetation in northwest Australia during the Paleogene, 66–23million years ago?" Australian Journal of Botany 66, n. 7 (2018): 556. http://dx.doi.org/10.1071/bt18143.
Testo completoAbstract (sommario):
Fossil pollen and spores preserved in drillcore from both the upper South Alligator River (SARV) in the Kakadu National Park, Northern Territory and the North-West Shelf, Western Australia provide the first record of plants and plant communities occupying the coast and adjacent hinterland in north-west Australia during the Paleogene 66 to 23million years ago. The palynologically-dominant woody taxon is Casuarinaceae, a family now comprising four genera of evergreen scleromorphic shrubs and trees native to Australia, New Guinea, South-east Asia and Pacific Islands. Rare taxa include genera now mostly restricted to temperate rainforest in New Guinea, New Caledonia, New Zealand, South-East Asia and/or Tasmania, e.g. Dacrydium, Phyllocladus and the Nothofagus subgenera Brassospora and Fuscospora. These appear to have existed in moist gorges on the Arnhem Land Plateau, Kakadu National Park. No evidence for Laurasian rainforest elements was found. The few taxa that have modern tropical affinities occur in Eocene or older sediments in Australia, e.g. Lygodium, Anacolosa, Elaeagnus, Malpighiaceae and Strasburgeriaceae. We conclude the wind-pollinated Oligocene to possibly Early Miocene vegetation in the upper SARV was Casuarinaceae sclerophyll forest or woodland growing under seasonally dry conditions and related to modern Allocasuarina/Casuarina formations. There are, however, strong floristic links to coastal communities growing under warm to hot, and seasonally to uniformly wet climates in north-west Australia during the Paleocene-Eocene.
20
Butcher, Ryonen, Margaret Byrne e Darren M. Crayn. "Evidence for convergent evolution among phylogenetically distant rare species of Tetratheca (Elaeocarpaceae, formerly Tremandraceae) from Western Australia". Australian Systematic Botany 20, n. 2 (2007): 126. http://dx.doi.org/10.1071/sb06017.
Testo completoAbstract (sommario):
Morphological and molecular investigations of taxon relationships among rare species of Tetratheca Sm. occurring near Koolyanobbing, Western Australia, have confirmed the distinctness of T. aphylla F.Muell., T. harperi F.Muell. and T. paynterae Alford and identified three new rare taxa from collections affiliated with T. aphylla and T. paynterae. The recognition of these taxa at specific and sub-specific ranks is based on their different degrees of morphological and molecular divergence, combined with geographic disjunction. Cladistic analysis of nrDNA internal transcribed spacer and cpDNA trnL-trnF sequences from a range of Tetratheca species from Western Australia and the eastern states indicates that T. aphylla, T. harperi and T. paynterae belong to three separate evolutionary lineages and that the endemism displayed among these taxa to small, disjunct ranges within the same geographic area, is a result of in situ speciation due to historical fragmentation. These results exemplify the extremely high conservation value of the Yilgarn banded ironstone ranges. The superficial similarity among the study taxa in having a ‘leafless’ habit can be seen to be adaptive convergence in response to the marginal and semi-arid environments in which they occur, and this character is highly homoplastic within the genus.
21
McDougall, K. L., R. J. Hobbs e G. E. St Hardy. "Vegetation of Phytophthora cinnamomi-infested and adjoining uninfested sites in the northern jarrah (Eucalyptus marginata) forest of Western Australia". Australian Journal of Botany 50, n. 3 (2002): 277. http://dx.doi.org/10.1071/bt01096.
Testo completoAbstract (sommario):
The vegetation of seven sites in the northern jarrah forest of Western Australia infested with Phytophthora cinnamomi was recorded and compared with adjoining vegetation. The number of species per quadrat was found to be the same in vegetation affected by P. cinnamomi as in healthy vegetation, although there were more species overall in affected vegetation. Vegetation of uninfested sites had a higher cover and more species per quadrat of trees and shrubs and lower cover and fewer species per quadrat of annual plants than vegetation of infested sites. Although many species that are known to be highly susceptible to infection by P. cinnamomi were rare at infested sites, only two (Banksia grandis and Tetratheca hirsuta) were absent from all of the 50-year-old infested parts of sites. Several species that are known to be highly susceptible to infection by P. cinnamomi were as common at infested as at healthy sites. The presence of such species at infested sites and the capacity of P. cinnamomi to infect species it does not kill suggest that this pathogen will persist and continue to influence future vegetation in the jarrah forest.
22
Bougoure, Jeremy, Mark Brundrett, Andrew Brown e Pauline F. Grierson. "Habitat characteristics of the rare underground orchid Rhizanthella gardneri". Australian Journal of Botany 56, n. 6 (2008): 501. http://dx.doi.org/10.1071/bt08031.
Testo completoAbstract (sommario):
Rhizanthella gardneri R.S.Rogers is an entirely subterranean mycoheterotrophic orchid known only from two isolated populations within south-western Western Australia (WA). This rare species appears restricted to habitats dominated by species of the Melaleuca uncinata complex. R. gardneri purportedly forms a tripartite relationship with Melaleuca1, via a connecting mycorrhizal fungus, for the purpose of carbohydrate and nutrient acquisition. Here, we quantify key climate, soil and vegetation characteristics of known R. gardneri habitats to provide baseline data for monitoring of known R. gardneri populations, to better understand how R. gardneri interacts with its habitat and to identify possible new sites for R. gardneri introduction. We found that the habitats of the two known R. gardneri populations show considerable differences in soil chemistry, Melaleuca structure and Melaleuca productivity. Multivariate analyses showed that both multidimensional scaling (MDS) and principal components analysis (PCA) ordinations of soil chemical characteristics were very similar. Individual sites within populations were relatively similar in all attributes measured, whereas overall northern and southern habitats were distinct from each other. These results suggest that R. gardneri can tolerate a range of conditions and may be more widespread than previously thought, given that there are extensive areas of Melaleuca thickets with similar habitat characteristics across south-western WA. Variability within the habitats of known R. gardneri populations suggests translocation of this species into sites with similar vegetation may be a viable option for the survival of this species.
23
Meney, K. A., K. W. Dixon e J. S. Pate. "Reproductive Potential of Obligate Seeder and Resprouter Herbaceous Perennial Monocots (Restionaceae, Anarthriaceae, Ecdeiocoleaceae) from South-western Western Australia". Australian Journal of Botany 45, n. 5 (1997): 771. http://dx.doi.org/10.1071/bt96028.
Testo completoAbstract (sommario):
Pre- and post-dispersal reproductive success was studied in 22 species from three related Southern Hemisphere families, Restionaceae, Ecdeiocoleaceae and Anarthriaceae. Pre-dispersal success was compared for resprouter and obligate seeder species using seed: ovule ratios and carpel: flower ratios. The data indicated a high level of variability between taxa but pre-dispersal reproductive success of obligate seeders was significantly higher (67% conversion of ovules to seeds) than that of resprouters (35%). Two seeders, an extremely rare species (‘Chordifex’ abortivus) and a strongly clonal species (Alexgeorgea subterranea), showed pre-dispersal reproductive success values lower than or equal to the mean value for resprouters. Post-dispersal reproductive success was predicted in terms of proportions of germinable seeds produced per ovule (as determined by in vitro germination of isolated embryos). Data again varied widely between taxa, averaging 23% conversion of ovules to seeds with no clear relationship to regeneration mode. The mean number of germinable seeds per culm ranged from 0.03 to 21 between species, with cases of particularly low ovule output and/or low germinability in critically low germinable seed numbers for a species. The regeneration potential of a subset of species was assessed as mean annual production of germinable seed per reproducing plant of a population. The data indicated low values (less than eight seeds per adult) for all but three highly fecund species, suggesting that germinable seed output in some species might be scarcely able to compensate for natural senescence or catastrophic loss of parent populations (e.g. after fire, disease, increased competition following eutrophication).
24
Barbetti, MJ. "Breakdown in resistance of subterranean clovers to clover scorch disease (Kabatiella caulivora)". Australian Journal of Agricultural Research 46, n. 3 (1995): 645. http://dx.doi.org/10.1071/ar9950645.
Testo completoAbstract (sommario):
In spring 1990, in the Australasian Subterranean Clover and Alternative Legume Improvement Program field plots at Denmark, Western Australia, subterranean clover cultivars and crossbred lines normally highly resistant to clover scorch disease caused by Kabatiella caulivora, were severely affected by this disease. Testing the response of subterranean clover varieties to Kabatiella isolates taken from plants from these plots indicates the arrival of a new race of the fungus. The new race differs from all other isolates in overcoming the previously outstanding resistance of cultivars Green Range, Junee, Daliak and Esperance.
25
Jones, R. A. C., B. A. Coutts e J. Hawkes. "Yield-limiting potential of Beet western yellows virus in Brassica napus". Australian Journal of Agricultural Research 58, n. 8 (2007): 788. http://dx.doi.org/10.1071/ar06391.
Testo completoAbstract (sommario):
Losses in seed yield and quality caused by infection with Beet western yellows virus (BWYV) alone or in combination with direct feeding damage by Myzus persicae (green peach aphid) were quantified in field experiments with Brassica napus (canola, oilseed rape) in the ‘grainbelt’ region of south-western Australia. Plants infected with BWYV and infested with M. persicae were introduced into plots early to provide infection sources and spread BWYV to B. napus plants. Insecticides were applied as seed dressings and/or foliar applications to generate a wide range of BWYV incidences in plots. Colonisation by vector aphids and spread of BWYV infection were recorded in the plots of the different treatments. At sites A (Medina) and B (Badgingarra) in 2001, foliar insecticide applications were applied differentially at first, but, later, ‘blanket’ insecticide sprays were applied to all plots to exclude any direct feeding damage by aphids. When BWYV infection at sites A and B reached 96% and 100% of plants, it decreased seed yield by up to 46% and 37%, respectively. Also, variation in BWYV incidence explained 95% (site A) and 96% (site B) of the variation in yield gaps, where for each 1% increase in virus incidence there was a yield decrease of 12 (site A) and 6 (site B) kg/ha. At both sites, this yield decline was entirely because fewer seeds formed on infected plants. At site B, BWYV infection significantly diminished oil content of seeds (up to 3%), but significantly increased individual seed weight (up to 11%) and erucic acid content (up to 44%); significant increases in seed protein content (up to 6–11%) were recorded at both sites. In field experiments at sites B and C (Avondale) in 2002, insecticides were applied as seed dressings or foliar sprays. At site B, when BWYV incidence reached 98%, the overall yield loss caused by BWYV and direct M. persicae feeding damage combined was 50%. At site C, when BWYV incidence reached 97%, the overall combined yield decline caused by BWYV and direct feeding damage was 46%. This research under Australian conditions shows that, when aphids spread it to B. napus plantings such that many plants become infected at an early growth stage, BWYV has substantial yield-limiting potential in B. napus crops. Although the results represent a worst case scenario, the losses were greater than those reported previously in Europe and are cause for concern for the Australian B. napus industry. When applied at 525 g a.i./100 kg of seed, imidacloprid seed dressing controlled insecticide-resistant M. persicae and effectively suppressed spread of BWYV for 2.5 months and increased seed yield by 84% at site B and 88% at site C. Therefore, provided that mixing the insecticide with seed is sufficiently thorough, dressing seed with imidacloprid before sowing provides good prospects for control of BWYV and M. persicae in B. napus crops.
26
Shepherd, Kelly A., Andrew Perkins, Joel Collins, Margaret Byrne e Kevin R. Thiele. "Morphological and molecular evidence supports the recognition of a new subspecies of the critically endangered Pityrodia scabra (Lamiaceae)". Australian Systematic Botany 26, n. 1 (2013): 1. http://dx.doi.org/10.1071/sb12009.
Testo completoAbstract (sommario):
Taxonomic delineation of closely related taxa can be difficult, particularly in regions such as southern Western Australia where a highly diverse flora exhibits complex patterns of subtle morphological variation and genetic structuring and where some taxa have highly disjunct populations. A combined approach utilising highly variable, non-coding chloroplast gene regions and morphological data is used here to help delimit cryptic taxa in the rare Western Australian species Pityrodia scabra A.S.George. The species comprises disjunct populations over 400 km of the Western Australian wheatbelt from near Wyalkatchem, Southern Cross and Lake Lefroy. Morphological features such as leaf phyllotaxy, calyx size and indumentum vary among the populations and provide some evidence for cryptic taxa. Phylogenetic analyses based on cpDNA psbA–trnH and psbD–trnT and nuclear external transcribed spacer (ETS) sequences revealed genetic distinctiveness between the Wyalkatchem (type) population and the Southern Cross and Lake Lefroy populations. This evidence, when used in conjunction with the morphological differences, provides support for the recognition of the new subspecies described herein as Pityrodia scabra subsp. dendrotricha K.A.Sheph. subsp. nov. This new subspecies is of conservation concern because it is currently known only from a few, isolated populations; the typical subspecies remains Critically Endangered because it comprises one extant population. A description of both subspecies, a key and images are provided.
27
Brennan, R. F., e M. D. A. Bolland. "Soil and tissue tests to predict the potassium requirements of canola in south-western Australia". Australian Journal of Experimental Agriculture 46, n. 5 (2006): 675. http://dx.doi.org/10.1071/ea04218.
Testo completoAbstract (sommario):
The predominantly sandy soils of south-western Australia have become potassium (K) deficient for spring wheat (Triticum aestivum L.) production due to the removal of K from soil in grain and hay. The K requirements of canola (rape, Brassica napus L.) grown in rotation with wheat on these soils are not known and were determined in the study reported here. Seed (grain) yield increases (responses) of canola to applications of fertiliser K occurred at sites where Colwell soil test K values (top 10 cm of soil) were <60 mg/kg soil. Grain yield responses to applied K occurred when concentrations of K in dried shoots were <45 g/kg for young plants 7 and 10 weeks after sowing and <35 g/kg for 18 weeks after sowing. Application of fertiliser K had no significant effects on either oil or K concentrations in grain.
28
Rossiter, RC, e WJ Collins. "Genetic diversity in Old Subterranean Clover (Trifolium subterraneum L.) Populations in Western Australia. I. Pastures sown initially to the Dwalganup strain". Australian Journal of Agricultural Research 39, n. 6 (1988): 1051. http://dx.doi.org/10.1071/ar9881051.
Testo completoAbstract (sommario):
Subterranean clover burrs were collected during summer from 28 sites, 10 of which were in the <500 mm annual rainfall zone. All sites had been sown to the Dwalganup strain, 30-50 years ago. Spaced plants were grown from seed from burr subsamples of each population. Several morphological characters, flowering dates, and oestrogenic isoflavones in late spring leaf samples were determined. At maturity, burr samples were collected from each plant, and the isozyme patterns in seeds were determined for eight enzyme systems using starch gel electrophoresis. Populations from the lower rainfall (< 500 mm) sites usually consisted of one or two strains - Dwalganup with or without Geraldton - and variant (or 'unknown') genotypes were very rare or absent. Populations from the higher rainfall (> 500 mm) sites, on the other hand, comprised about 50% of a few known strains - mostly Dwalganup and/or Dinninup - the remaining 50% consisting of numerous variant genotypes. Infrequent outcrossing between the Dwalganup and Mt Barker strains is the likely major source of this variation. Possible explanations for the lack of variant genotypes in the lower rainfall zone are discussed.
29
Robinson, T. P., G. Di Virgilio, D. Temple-Smith, J. Hesford e G. W. Wardell-Johnson. "Characterisation of range restriction amongst the rare flora of Banded Ironstone Formation ranges in semiarid south-western Australia". Australian Journal of Botany 67, n. 3 (2019): 234. http://dx.doi.org/10.1071/bt18111.
Testo completoAbstract (sommario):
Banded Ironstone Formation (BIF) ranges feature numerous rare and endemic plant species. We tested whether non-occurrence in neighbouring ranges is due to habitat dissimilarity across five groups of proximal ranges for three sets of species (18 taxa). Set 1 comprised 15 BIF-specialist species centred on the Helena and Aurora Range (HAR); Set 2, of one BIF species endemic to Mt Jackson and Set 3, of two non-BIF species. All species were used as input into ecological niche models to determine the importance and behaviour of five environmental variables derived from 2m resolution LiDAR imagery over 1605km2, extrapolate habitat suitability and compare niche similarity. We hypothesised that if BIF species are not range-restricted, suitable habitat will be found on all five groups and variable importance and behaviour will be similar for Sets 1 and 2 but not for Set 3. Topographical control on surface hydrology is the most important predictive variable for most BIF species, with ruggedness and shade also important to species in Sets 1–2 but not Set 3, which either preferred flat plains or had no preference (habitat generalist). We conclude that habitat suitability is not range restrictive. Such endemism is more likely a result of stochasticity and limited seed dispersal.
30
Perold, S. M. "Studies in the Sphaerocarpales (Hepaticae) from southern Africa. 1. The genus Monocarpus and its only member, M. sphaerocarpus". Bothalia 29, n. 2 (1 ottobre 1999): 225–30. http://dx.doi.org/10.4102/abc.v29i2.592.
Testo completoAbstract (sommario):
A taxonomic account of the genus Monocarpus and its only species, M. sphaerocarpus, is presented. The species was initially discovered on salt pans in Western Australia, and only later, in southern Africa. It is extremely rare and the structure of the minute thalli is difficult to determine, also to describe and to illustrate. As far as could be determined, no SEM micrographs o f the thalli and spores have been published before, nor has the capsule wall been illustrated.
31
Krauss, Siegfried L., e Janet Anthony. "Genetic impacts of habitat loss on the rare Banded Ironstone Formation endemic Ricinocarpos brevis (Euphorbiaceae)". Australian Journal of Botany 67, n. 3 (2019): 183. http://dx.doi.org/10.1071/bt18131.
Testo completoAbstract (sommario):
Ricinocarpos brevis (Euphorbiaceae) is a declared rare species currently known from only three Banded Ironstone Formation (BIF) ranges (Perrinvale, Johnston and Windarling Ranges) in the Yilgarn region of Western Australia. The present study assessed the potential impact of proposed mining on genetic diversity within R. brevis. Approximately 30 plants were sampled from each of 14 sites across the known distribution of R. brevis. Genetic variation and its spatial structure was assessed with 144 polymorphic AFLP markers that were generated by two independent primer pairs: M-CTG/P-AC (81 markers) and M-CTA/P-AC (63 markers). Hierarchical spatial genetic structure was assessed by an analysis of molecular variance (AMOVA), Mantel tests of association between genetic- and geographic-distance and ordination. Specific attention was given to the extent of genetic differentiation of the three populations on the Windarling Range W4 deposit, which was proposed for mining operations. Strong genetic differentiation (ΦPT=0.186–0.298) among the three ranges was found. Genetic differentiation of the Johnston Range populations from Windarling and Perrinvale was greater than expected under isolation by distance predictions, suggesting adaptive genetic differentiation driven by site environmental differences, reflected by differences in plant community, substrate and landscape features. In contrast, genetic differentiation among the three Windarling Range regions (W2, W3, W4) was weaker (ΦPT=0.055–0.096). Mean pairwise ΦPT=0.078 for the 10 Windarling sites, which was unchanged with the removal of the W4 populations. In addition, none of the markers scored were unique to the W4 populations. Thus, for this set of markers, the removal of plants on the Windarling Range W4 deposit had little impact on genetic diversity within R. brevis. Strong concordance in results from the independent datasets generated by the two AFLP primer pairs provides overall support for the conclusions drawn.
32
Vincent, Brian J., Sarah Barrett, Anne Cochrane e Michael Renton. "Germination characteristics and the relationship between population structure, soil seed bank density and fire response in the rare endemic Stachystemon vinosus (Halford & R.J.F.Hend.) (Euphorbiaceae) from southern Western Australia". Seed Science Research 29, n. 2 (giugno 2019): 124–34. http://dx.doi.org/10.1017/s0960258519000126.
Testo completoAbstract (sommario):
AbstractThe regeneration niche defines the specific environmental requirements of the early phases of a plant's life cycle. It is critical for the long-term persistence of plant populations, particularly for obligate seeders that are highly vulnerable to stochastic events in fire-prone ecosystems. Here, we assessed germination characteristics and the relationship between population structure, soil seed bank density and fire response in Stachystemon vinosus (Euphorbiaceae), a rare endemic shrub from Western Australia, from burnt and long unburnt habitats. Many plants in long unburnt habitat were similar in size to those in recently burnt habitat. Soil seed bank density was related to plant abundance and fire history with density lower in burnt than unburnt sites. Thus, inter-fire recruitment may play a critical role in the requirements of the study species. To assess the dormancy status and germination requirements we used a ‘move-along’ experiment with temperatures from six seasonal phases of the year. Seeds were incubated under light and dark conditions, with and without smoked water, and with and without dry after-ripening. Germination was most effective when seeds were treated with smoked water and incubated in the dark at temperatures resembling autumn/winter conditions. After-ripening increased germination in light and dark incubated seeds in the absence of smoked water but was unnecessary for optimal germination in smoked water treated seeds. Irrespective of treatment, seeds showed a requirement for cooler temperatures for germination. These results suggest that rising temperatures and changes in fire regime associated with global warming may alter future germination responses of Stachystemon vinosus.
33
Start, A. N. "Mistletoe flora (Loranthaceae and Santalaceae) of the Kimberley, a tropical region in Western Australia, with particular reference to fire". Australian Journal of Botany 61, n. 4 (2013): 309. http://dx.doi.org/10.1071/bt13021.
Testo completoAbstract (sommario):
The mistletoe flora of the tropical Kimberley region of Western Australia was studied over a 30-year period, with a particular emphasis on distributions, use of hosts and effects of fire. The results were compared with those of a similar study undertaken in the Pilbara, a more arid tropical region in the same State. The flora consisted of one genus with three species in the Santalaceae and five genera with 22 species (one with two varieties) in the Loranthaceae. Amyema was the largest genus in both regions. Four species are regarded as Kimberley endemics but two of them may also occur in the Northern Territory. Most species occurred in three or more of five Kimberley bioregions. However, six species were recorded only from the North Kimberley where they were all rare. Host records included 165 species from 33 families. Fabaceae (particularly Acacia) and Myrtaceae (particularly Eucalyptus and Corymbia) were the most important. The perfect dichotomy between species using fabaceous and myrtaceous hosts in the Pilbara was strong but imperfect in the Kimberley. Fire responses of two species were not observed. Two (perhaps three) taxa were able to resprout, whereas the remaining taxa were killed if scorched. Most species occurred, at least occasionally, in relatively fire-safe refugia. Nevertheless, fire is eroding distributions of many species and may be threatening some, particularly the rare North Kimberley species.
34
Sinclair, Elizabeth, Belinda Cheetham, Siegfried Krauss e Richard Hobbs. "Morphological and molecular variation in Conospermum triplinervium (Proteaceae), the tree smokebush: implications for bushland restoration". Australian Journal of Botany 56, n. 5 (2008): 451. http://dx.doi.org/10.1071/bt07137.
Testo completoAbstract (sommario):
Ecological restoration benefits from information on population genetic structure and variation within a species to make informed decisions on where to source material of the local genetic provenance. Conospermum triplinervium is extremely rare in Bold Park, a large bushland remnant currently undergoing restoration in Perth, Western Australia. We sampled plants from Bold Park and six other native populations across the northern half of the species’ range to assess patterns of morphological and genetic variation. There was considerable variation across six leaf measures with significant differentiation among some populations. The molecular data showed a high level of population structure (ΘB = 0.4974), with varying degrees of spatial overlap among populations in an ordination plot. Significant differentiation was observed among all pairs of populations, except for Bold Park and its geographically closest populations at Kings Park and Neerabup. These two populations had greater genetic variation (50.9% and 54.5% polymorphic markers, respectively) than did that at Bold Park (20.2%). The small Bold Park population would benefit from augmentation (via cuttings) from local plants. However, in the longer term, should the Bold Park population show evidence of declining viability, then material should be sourced from the genetically similar Kings Park population to increase genetic variation whilst also maintaining genetic integrity.
35
Eshraghi, L., M. P. You e M. J. Barbetti. "First Report of White Leaf Spot Caused by Pseudocercosporella capsellae on Brassica juncea in Australia". Plant Disease 89, n. 10 (ottobre 2005): 1131. http://dx.doi.org/10.1094/pd-89-1131b.
Testo completoAbstract (sommario):
Brassica juncea (L.) Czern & Coss (mustard) has potential as a more drought-tolerant oilseed crop than the Brassica napus, and the first two canola-quality B. juncea cultivars will be sown as large strip trials across Australia in 2005. This will allow commercial evaluation of oil and meal quality and for seed multiplication for the commercial release Australia-wide in 2006. Inspection of experimental B. juncea field plantings at Beverley (32°6′30″S, 116°55′22″E), and Wongan Hills (30°50′32″S, 116°43′33″E), Western Australia in September 2004 indicated the occurrence of extensive leaf spotting during B. juncea flowering. Symptoms of this disease included as many as 15 or more grayish white-to-brownish spot lesions per leaf, often with a distinct brown margin. Some elongate grayish stem lesions were also observed as reported earlier for B. napus oilseed rape (1). When affected materials were incubated in moist chambers for 48 h, abundant conidia typical of Pseudocercosporella capsellae (Ellis & Everh.) Deighton were observed that matched the descriptions of conidia given by Deighton (2) and those on B. napus in Western Australia (1). Five single-spore cultures from lesions were grown on water agar (WA) where the colonies characteristically produced purple-pink pigment in the agar after 2 weeks growth in an incubator maintained at 20°C with a 12-h photoperiod (3). Since agar cultures of P. capsellae rarely produce conidia (3), this observation helped with the verification of the cultures. Mycelial inoculum from these cultures was used to inoculate cotyledons of 50 7-day-old plants of B. juncea to satisfy Koch's postulates. Small pieces of mycelia were teased out from the surface of the growing margin of potato dextrose agar (PDA) cultures and inoculated onto both lobes of each cotyledon and plants incubated in a 100% humidity chamber for 48 h within a controlled environment room maintained at 20/15°C (day/night) with a 12-h photoperiod. After 2 weeks, lesions 5 to 8 mm in diameter were observed on the cotyledons. There were no symptoms on control plants that were treated with water only. Lesions on infected cotyledons incubated on moist filter paper for 24 h produced abundant cylindrical conidia showing 2 to 3 septa measuring 42.9 to 71.4 μm long and 2.9 to 3.1 μm wide. Single-spore isolations from these conidia produced typical P. capsellae colonies showing purple-pink pigments in WA, and dark, compacted, and slow-growing colonies with a dentate margin on PDA. White leaf spot caused by P. capsellae is an important disease of crucifers worldwide, but to our knowledge, this is the first report of P. capsellae on B. juncea in Australia. In Western Australia, P. capsellae occurs on B. napus oilseed rape (1) and in 1956, 1984, and 1987, it was recorded on B. rapa, B. oleracea, and B. chinensis, respectively (4), and on the same range of Brassica hosts in other regions of Australia. References: (1) M. J. Barbetti and K. Sivasithamparam. Aust. Plant Pathol.10:43, 1981. (2) F. C. Deighton. Commonw. Mycol. Inst. Mycol. Pap. 133:42, 1973. (3) S. T. Koike. Plant Dis. 80:960, 1996. (4) R. G. Shivas. J. R. Soc. West. Aust. 72:1, 1989.
36
Yates, Colin J., Philip G. Ladd, David J. Coates e Shelley McArthur. "Hierarchies of cause: understanding rarity in an endemic shrub Verticordia staminosa (Myrtaceae) with a highly restricted distribution". Australian Journal of Botany 55, n. 3 (2007): 194. http://dx.doi.org/10.1071/bt06032.
Testo completoAbstract (sommario):
Verticordia staminosa C.Gardner & A.C.George subsp. staminosa is an extremely rare shrub occurring as an isolated population of ~1200 plants on a granite outcrop in the semi-arid agricultural region of Western Australia, separated from its closest relative V. staminosa subsp. cylindracea by 400 km. We aimed to determine a hierarchy of causes for explaining the extremely restricted distribution of subsp. staminosa, and to determine the genetic relationships among populations within both subspecies. We measured allozyme variation in all known populations of the two subspecies. There were exceptionally high levels of genetic divergence between subsp. staminosa and subsp. cylindracea, including an apparent duplication of the gene encoding phosphoglucomutase, leading to an additional gene in subsp. cylindracea. These findings combined with UPGMA analysis indicate a very long period of historical separation, perhaps originating in the early Pleistocene. Genetic variation was partitioned mostly between rather than within populations, with very low levels of genetic variation within populations of both subspecies. For subsp. staminosa we quantified seed production for three consecutive years and demography for five consecutive years. We used transition matrix models to describe the shrub’s population dynamics and stochastic simulations to explicitly compare the effects of low rainfall and disturbance on population viability. Verticordia staminosa subsp. staminosa produces large numbers of seeds each year and has flower to fruit ratios greater than reported for related rare and common congeners. Seedling recruitment occurs in most years, with pulses in the wettest years. The mean finite population growth rate was 1.031. Elasticity analyses showed that population growth rate was more sensitive to stasis of established plants than to seedling recruitment. Population viability declined with lower rainfall and increased fire-related mortality of adult plants. Rarity in subsp. staminosa is best explained by evolutionary history and the interaction of climate change and disturbances such as fire that kill plants. Climatic fluctuations since the late Pliocene might have led to stochastic extinction episodes of populations on other granite outcrops, resulting in the currently restricted distribution. We discuss the implications of our findings for management of the species.
37
Brundrett, Mark C. "A Comprehensive Study of Orchid Seed Production Relative to Pollination Traits, Plant Density and Climate in an Urban Reserve in Western Australia". Diversity 11, n. 8 (26 luglio 2019): 123. http://dx.doi.org/10.3390/d11080123.
Testo completoAbstract (sommario):
The pollination of 20 common terrestrial orchids was studied in a 60-ha urban banksia and eucalypt dominated woodland in Western Australia. Five years of data (24,000 flowers, 6800 plants) measured fruit set relative to floral areas, capsule volumes, climate, phenology, pollination mechanisms, disturbance tolerance and demography. Pollination varied from 0–95% of flowers, floral displays from 90–3300 mm2 and capsules from 15–1300 mm3 per spike. Pollination traits strongly influenced outcomes, with self-pollination highest (59—95%), followed by sexually deceptive autumn or winter-flowering (18–39%), visual deception (0–48%) and sexually deceptive spring-flowering (13–16%). Pollination was limited by drought in autumn or spring and cool winter temperatures. Some orchids were resilient to drought and one formed seed after the leaves withered. Plant density had the greatest impact on fruit set for orchids forming large groups, especially for sexually deceptive pollination. Consequently, small group average (SGA) pollination was up to 4× greater than overall averages and peak seed production occurred in the best locations for genetic exchange and dispersal. SGA rates and seedpod volumes were strongly linked to clonality, but not to demographic trends. Resource competition limited flowering at higher plant densities and competition within spikes resulted in smaller, later-forming seedpods. Pollination data from co-occurring common orchids identified five evolutionary trade-offs linked to pollination, provided baseline data for rare species and revealed impacts of changing climate.
38
Tremblay, Raymond L., Maria-Eglée Perez, Matthew Larcombe, Andrew Brown, Joe Quarmby, Doug Bickerton, Garry French e Andrew Bould. "Dormancy in Caladenia: a Bayesian approach to evaluating latency". Australian Journal of Botany 57, n. 4 (2009): 340. http://dx.doi.org/10.1071/bt08163.
Testo completoAbstract (sommario):
Dormancy is common in many terrestrial orchids in southern Australia and other temperate environments. The difficulty for conservation and management when considering dormancy is ascertaining whether non-emergent plants are dormant or dead. Here we use a multi-state capture–recapture method, undertaken over several seasons, to determine the likelihood of a plant becoming dormant or dying following its annual emergent period and evaluate the frequency of the length of dormancy. We assess the transition probabilities from time series of varying lengths for the following nine terrestrial orchids in the genus Caladenia: C. amoena, C. argocalla, C. clavigera, C. elegans, C. graniticola, C. macroclavia, C. oenochila, C. rosella and C. valida from Victoria, South Australia and Western Australia. We used a Bayesian approach for estimating survivorship, dormancy and the likelihood of death from capture–recapture data. Considering all species together, the probability of surviving from one year to the next was ~86%, whereas the likelihood of observing an individual above ground in two consecutive years was ~74%. All species showed dormancy of predominantly 1 year, whereas dormancy of three or more years was extremely rare (<2%). The results have practical implications for conservation, in that (1) population sizes of Caladenia species are more easily estimated by being able to distinguish the likelihood of an unseen individual being dormant or dead, (2) population dynamics of individuals can be evaluated by using a 1–3-year dormancy period and (3) survey effort is not wasted on monitoring individuals that have not emerged for many years.
39
Li, H., K. Sivasithamparam e M. J. Barbetti. "Breakdown of a Brassica rapa subsp. sylvestris Single Dominant Blackleg Resistance Gene in B. napus Rapeseed by Leptosphaeria maculans Field Isolates in Australia". Plant Disease 87, n. 6 (giugno 2003): 752. http://dx.doi.org/10.1094/pdis.2003.87.6.752a.
Testo completoAbstract (sommario):
Blackleg, caused by Leptosphaeria maculans, is a major disease of oilseed rape (Brassica napus) grown in Canada, Europe, and Australia. Cv. Surpass 400 was released in Australia in 2000 as the most resistant cultivar to L. maculans. It carries a single dominant resistance gene from B. rapa subsp. sylvestris. This cultivar usually shows a hypersensitive response to L. maculans characterized by small, dark brown lesions that are necrotic, localized, and without pycnidia on cotyledons, leaves, and stems. However, in 2001 on a Western Australian experimental farm, a small proportion of the lesions on the lower stem and crown region of cv. Surpass 400 were typical of those observed in susceptible cultivars, which were brown, necrotic lesions with a darker margin, but they contained fewer pycnidia. Forty seedlings of cv. Surpass 400 and susceptible cv. Westar were inoculated with pycnidiospore suspensions (106/ml) of each of 18 isolates taken from lesions on cv. Surpass 400. All 18 isolates caused collapse of cotyledons of susceptible cv. Westar. Four of these isolates caused large cotyledon lesions with some pycnidia on cv. Surpass 400. Three of these four isolates were subsequently inoculated onto 60 seedlings per isolate, at each of the four cotyledon lobes of each seedling of the two cultivars. Inoculated plants were assessed for disease severity on cotyledons and transplanted to the field 14 days after inoculation. The cotyledons of inoculated cv. Surpass 400 showed characteristic large, necrotic lesions with pycnidia, while the cotyledons of cv. Westar had collapsed and contained a mass of pycnidia. Blackleg disease severity in the crown region of the stem was assessed at 2 weeks before harvest. Fifty-four percent of the cv. Surpass 400 transplanted inoculated plants subsequently developed susceptible symptoms of crown cankers on stems. These symptoms were deep, girdling, brown lesions on the plant crowns with some pycnidia. One hundred percent of cv. Westar plants were infected and dead at this stage. This confirmed the ability of these field isolates to overcome the single dominant resistance gene present in cv. Surpass 400. To our knowledge, this is the first report of breakdown of a single dominant B. rapa subsp. sylvestris gene based resistance to blackleg in oilseed rape in the field.
40
Abdullah, Araz S., Mark R. Gibberd e John Hamblin. "Co-infection of wheat by Pyrenophora tritici-repentis and Parastagonospora nodorum in the wheatbelt of Western Australia". Crop and Pasture Science 71, n. 2 (2020): 119. http://dx.doi.org/10.1071/cp19412.
Testo completoAbstract (sommario):
The pathogenic fungal species Pyrenophora tritici-repentis (Ptr) and Parastagonospora nodorum (Pan) are common in many wheat-producing parts of the world. These two fungi cause tan spot and septoria nodorum blotch, respectively, frequently co-infecting wheat leaves. Empirical studies of this and other co-infections are rare because of the visual similarity of symptoms and the lack of robust methods for quantifying the abundance of pathogens associated with the co-infection. Here, we use a recently developed molecular method that simultaneously distinguishes and quantifies, in DNA equivalent, the abundance of Ptr and Pan, thereby allowing the prevalence of co-infection to be determined. The study examines the prevalence of co-infection under field conditions, at three widely spaced sites and on three wheat (Triticum aestivum L.) cultivars varying in disease resistance. Co-infection by Ptr and Pan was almost ubiquitous (overall prevalence 94%), and Pan DNA was detected only in association with Ptr. Although Ptr and Pan commonly co-infected, Ptr was more abundant during early and mid-season, at 80% of total fungal abundance when crops were tillering and 67% at booting stage. Pan became as abundant as Ptr when crops reached flowering. Variability in total fungal abundance and disease severity was primarily determined by cultivar; however, Ptr was the more abundant despite differences in cultivar resistance to this pathogen.
41
Ohlsen, Daniel J., Leon R. Perrie, Lara D. Shepherd e Michael J. Bayly. "Taxonomic status and distribution of the critically endangered Christmas Island spleenwort (Asplenium listeri, Aspleniaceae): it is not as rare as we thought". Australian Systematic Botany 27, n. 6 (2014): 372. http://dx.doi.org/10.1071/sb14047.
Testo completoAbstract (sommario):
Asplenium listeri C.Chr. has been considered endemic to Christmas Island and is one of only two fern species listed as Critically Endangered under Australia’s Environment Protection and Biodiversity Conservation Act. Its status as a distinct species has been questioned because of morphological similarity to the widespread A. polyodon G.Forst., which also occurs on Christmas Island. Molecular analyses revealed that A. listeri and plants attributed to A. polyodon from coastal limestone in New Caledonia and Vanuatu share the same rbcL, trnL–trnF and rps4–trnS haplotype and that other samples of A. polyodon in Australia and the south-western Pacific belong to three separate molecular lineages. One of these lineages is formed by epiphytic A. polyodon from Christmas Island and has a chloroplast haplotype closely related to that of A. listeri, differing by four mutations. The A. listeri haplotype and each of the three A. polyodon lineages are associated with morphological characters and are all worthy of recognition as separate species. Asplenium listeri is here expanded to include limestone dwelling populations in the Pacific previously assigned to A. polyodon. This greatly extends the geographic range of A. listeri, and its conservation status should be revised accordingly. Application of correct names to all species in the A. polyodon complex requires further molecular sampling throughout its geographic range and clarification of how type material relates to each of the molecular groups.
42
Shearer, B. L., C. E. Crane, R. G. Fairman e M. J. Grant. "Occurrence of Armillaria luteobubalina and Pathogen-mediated Changes in Coastal Dune Vegetation of South-western Australia". Australian Journal of Botany 45, n. 5 (1997): 905. http://dx.doi.org/10.1071/bt96084.
Testo completoAbstract (sommario):
Sixty-two Armillaria luteobubalina Watling & Kiledisease centres were assessed along the coast from near Cervantes, 160 kmnorth-west of Perth, to Cape Arid, 120 km east of Esperance. Disease centresranged from 0.02 to 6.5 ha in size (mean ± s.e., 1.7 ± 0.2 ha).Most disease centres were active, with mainly old deaths occurring in only7% of centres. Impact was low in only 3% of centres. Diseasecentres mainly occurred on calcareous sands of Holocene dune systems.Susceptible hosts from the Proteaceae, Mimosaceae and Myrtaceae tended to bedominant small trees or shrubs and their death resulted in centres composedmainly of sedges or small shrubs and ground-cover species from a range offamilies. Percentage cover of susceptible plant species was significantly lessin disease centres than adjacent healthy areas. Cover of resistant speciestended to be greater in disease centres than adjacent healthy areas, althoughdifferences were not significant. In association with changes in communitystructure, infection resulted in more bare ground in disease centres thanamongst healthy vegetation. Infection had minimal effect on species richness.The mortality progress curve for the susceptible speciesDryandra sessilis (Knight) Domin increased at a meanapparent infection rate of 0.31 ± s.e. 0.12year-1. A disease centre extended at the rate of 0.004ha year-1 between 1964 and 1983 and 0.07 hayear-1 during the period 1981–1989. Diseaseextension per year was not correlated with yearly rainfall. Threatened taxakilled by A. luteobubalina included the rare andendangered Banksia brownii Baxter ex R.Br.,B. occidentalis R.Br. subsp.formosa Hopper, andB. verticillata R.Br. This is the first report ofdisease significantly altering the structure and composition of coastalvegetation of south-western Australia.Armillaria luteobubalina is a significant additional,and hitherto unrecognised, selection pressure on coastal dune vegetationcommunities, and an important consideration in their management andconservation.
43
Wright, Wendy, Xuan Zhu e Mateusz Okurowski. "Identification of key environmental variables associated with the presence of Toothed Leionema (Leionema bilobum serrulatum) in the Strzelecki Ranges, Victoria, Australia". Australian Journal of Botany 59, n. 3 (2011): 207. http://dx.doi.org/10.1071/bt10197.
Testo completoAbstract (sommario):
Toothed Leionema is one of four subspecies of Leionema bilobum from the Rutaceae family. A dense shrub or small tree, growing to ~4 m high, it is a poorly investigated species which is considered rare in Victoria, Australia. This paper presents the results of a study using Geographical Information Systems and Weights-of-Evidence predictive modelling to assess the importance of seven environmental factors in determining habitat suitability for this species in the Strzelecki Ranges, Victoria. This method is particularly useful in understanding the distribution of rare species, especially where the ecology of the species of interest is not well understood. Of the seven environmental factors considered here, four were found to be important: elevation, aspect, distance to water and distance to plantation (disturbed) areas. The modelling results indicate that areas with elevations between 350 and 550 m and a dominant south-western aspect that are close to plantation areas (within 700 m), and to water (within 1100–1200 m), provide potentially suitable habitat for Toothed Leionema in the region.
44
Brundrett, Mark C. "Scientific approaches to Australian temperate terrestrial orchid conservation". Australian Journal of Botany 55, n. 3 (2007): 293. http://dx.doi.org/10.1071/bt06131.
Testo completoAbstract (sommario):
This review summarises scientific knowledge concerning the mycorrhizal associations, pollination, demographics, genetics and evolution of Australian terrestrial orchids relevant to conservation. The orchid family is highly diverse in Western Australia (WA), with over 400 recognised taxa of which 76 are Declared Rare or Priority Flora. Major threats to rare orchids in WA include habitat loss, salinity, feral animals and drought. These threats require science-based recovery actions resulting from collaborations between universities, government agencies and community groups. Fungal identification by DNA-based methods in combination with compatibility testing by germination assays has revealed a complex picture of orchid–fungus diversity and specificity. The majority of rare and common WA orchids studied have highly specific mycorrhizal associations with fungi in the Rhizoctonia alliance, but some associate with a wider diversity of fungi. These fungi may be a key factor influencing the distribution of orchids and their presence can be tested by orchid seed bait bioassays. These bioassays show that mycorrhizal fungi are concentrated in coarse organic matter that may be depleted in some habitats (e.g. by frequent fire). Mycorrhizal fungi also allow efficient propagation of terrestrial orchids for reintroduction into natural habitats and for bioassays to test habitat quality. Four categories of WA orchids are defined by the following pollination strategies: (i) nectar-producing flowers with diverse pollinators, (ii) non-rewarding flowers that mimic other plants, (iii) winter-flowering orchids that attract fungus-feeding insects and (iv) sexually deceptive orchids with relatively specific pollinators. An exceptionally high proportion of WA orchids have specific insect pollinators. Bioassays testing orchid-pollinator specificity can define habitats and separate closely related species. Other research has revealed the chemical basis for insect attraction to orchids and the ecological consequences of deceptive pollination. Genetic studies have revealed that the structure of orchid populations is influenced by pollination, seed dispersal, reproductive isolation and hybridisation. Long-term demographic studies determine the viability of orchid populations, estimate rates of transition between seedling, flowering, non-flowering and dormant states and reveal factors, such as grazing and competition, that result in declining populations. It is difficult to define potential new habitats for rare orchids because of their specific relationships with fungi and insects. An understanding of all three dimensions of orchid habitat requirements can be provided by bioassays with seed baits for fungi, flowers for insects and transplanted seedlings for orchid demography. The majority of both rare and common WA orchids have highly specific associations with pollinating insects and mycorrhizal fungi, suggesting that evolution has favoured increasing specificity in these relationships in the ancient landscapes of WA.
45
Joyce, E. M., R. Butcher, M. Byrne, P. F. Grierson, M. Hankinson e K. R. Thiele. "Taxonomic resolution of the Tetratheca hirsuta (Elaeocarpaceae) species complex using an integrative approach". Australian Systematic Botany 30, n. 1 (2017): 1. http://dx.doi.org/10.1071/sb16040.
Testo completoAbstract (sommario):
The Tetratheca hirsuta Lindl. species complex from south-west Western Australia is one of the last unresolved complexes in this Australian endemic genus, and comprises the highly variable T. hirsuta, two rare, phrase-named taxa, and the closely allied T. hispidissima Steetz. An integrative approach, incorporating multivariate morphometric analysis and molecular phylogenetic and phenetic analyses of nrDNA (ETS) and cpDNA (ndhF–trnL, rpl16, trnS–trnG5ʹ2S), was used to investigate taxonomic boundaries within the complex. Morphological data showed clear divergence within the complex, and allowed several taxonomically uncertain individuals to be assigned. Phenetic and phylogenetic analyses of ETS showed substantial congruence with morphology, indicating that the groups recognised through morphometric analyses are also genetically divergent. By comparison, the chloroplast regions yielded incongruent gene trees, perhaps owing to incomplete lineage sorting, hybridisation or slow evolution of cpDNA. The present results support the recognition of the following four taxa: a morphologically and geographically expanded T. hispidissima, which is highly divergent from the remainder of the complex, and a closer grouping of T. hirsuta subsp. boonanarring Joyce & R.Butcher subsp. nov., T. hirsuta subsp. viminea (Lindl.) Joyce comb. et stat. nov. and T. hirsuta subsp. hirsuta.
46
McDonald, M. W. "Revision of Acacia tumida (Leguminoseae: Mimosoideae) and close allies, including the description of three rare taxa". Australian Systematic Botany 16, n. 2 (2003): 139. http://dx.doi.org/10.1071/sb02012.
Testo completoAbstract (sommario):
Acacia tumida F.Muell ex. Benth. is a wide-ranging species in north-western Australia, with high morphological variability. Overseas it is cultivated for firewood, windbreaks and sand stabilisation. To assist in its domestication, the taxonomy of A. tumida is revised and its close allies, A. difficilis Maiden and A. retinervis Benth., circumscribed. The following six new taxa in the A. tumida group are described: A. areolata M.W.McDonald, A.�dissimilis M.W.McDonald, A. seclusa M.W.McDonald (syn. A. tumida var. pubescens Maiden), A. tumida var. extenta M.W.McDonald, A. tumida var. kulparn M.W.McDonald and A. tumida var. pilbarensis M.W.McDonald. A lectotype is designated for A. retinervis. A key to the group, which also includes A. brassii Pedley, A. eriopoda Maiden & Blakely, A. meiosperma (Pedley) Pedley, A. mountfordiae Specht & A. torulosa Benth., is presented. Genetic variation and phylogeny in A. areolata and A. seclusa on the basis of allozymes are briefly discussed. On the basis of present knowledge, three of the new taxa (A. dissimilis, A. seclusa, A. tumida var. extenta) have restricted distributions and warrant formal legislative protection.
47
Thurling, N., e R. Kaveeta. "Yield improvement of oilseed rape (Brassica napus L.) in a low rainfall environment. I. Utilization of genes for early flowering in primary and secondary gene pools". Australian Journal of Agricultural Research 43, n. 3 (1992): 609. http://dx.doi.org/10.1071/ar9920609.
Testo completoAbstract (sommario):
The extent to which time to flowering of a Brassica napus commercial cultivar could be reduced through utilization of genes in its primary and secondary pools was examined with particular reference to yield improvement in lower rainfall environments. The B. napus breeding line RU2 and the B. campestris population Chinoli C42, which were used as sources of early flowering genes to be incorporated into the commercial B. napus cultivar Wesbrook, flowered significantly earlier than Wesbrook with or without vernalization and/or long days. In the cross of Wesbrook with RU2, the substantial variation in flowering time in the F2 was highly heritable (hn2 = 0.79), and some plants in the F2 and first backcross to Wesbrook flowered earlier than the early flowering parent RU2. Many lines flowering much earlier than Wesbrook were still obtained after two generations of recurrent backcrossing to Wesbrook and subsequent selfing without selection at any stage. Variation in flowering time among these lines primarily reflected differences in growth rate as measured by the rate of leaf node development. F2 plants derived from the cross between Wesbrook and the B. campestris population Chinoli C42 varied widely in chromosome number and flowering time, but there was no relationship between pre-anthesis development and chromosome number. Two generations of recurrent backcrossing to Wesbrook and subsequent selfing without selection at any stage produced a series of lines all having the normal B. napus chromosome complement. All these lines flowered significantly earlier than Wesbrook, and the earliest flowering line flowered at the same time as the early flowering B. campestris parent. The implications of these results are discussed with particular reference to developing agronomically superior B. napus cultivars closely adapted to lower rainfall environments in the Western Australian wheatbelt and elsewhere in southern Australia.
48
Batty, A. L., K. W. Dixon, M. Brundrett e K. Sivasithamparam. "Long-term storage of mycorrhizal fungi and seed as a tool for the conservation of endangered Western Australian terrestrial orchids". Australian Journal of Botany 49, n. 5 (2001): 619. http://dx.doi.org/10.1071/bt01029.
Testo completoAbstract (sommario):
The impact of seed drying, seed storage and development of testing procedures for seed viability assessment was undertaken for a selection of common taxa with congeners that are rare and endangered (Caladenia, Diuris, Pterostylisand Thelymitra). Freshly collected seed showed significantly lower levels of germination compared with seed that had been subjected to drying over silica gel for 24 h. Seed dried over silica gel for 24 h and plunged into liquid nitrogen exhibited a further increase in germination levels. Germination of seed stored at 4, 18 or 22˚C for 1 year was substantially higher than freshly collected seed (4 weeks after dehiscence), but germination was highest overall after storage of dried seed in liquid nitrogen (–196˚C). Mycorrhizal fungi that promote the germination and growth of plants were also successfully preserved in liquid nitrogen. The use of cryoprotectants on fungal isolates had no observable deleterious effects on fungal regeneration. Histochemical staining procedures (tetrazolium, fluorescein diacetate and Evans blue) substantially overestimated seed viability, relative to symbiotic seed germination, for most seed treatments indicating a need for re-evaluation of the effectiveness of staining procedures for testing viability. The implications of the long-term ex situ storage of orchid seed and fungal symbionts for the conservation of endangered orchids is discussed.
49
Jones, BA, RA How e DJ Kitchener. "A field study of Pseudocheirus occidentalis (Marsupialia : Petauridae) I. Distribution and Habitat". Wildlife Research 21, n. 2 (1994): 175. http://dx.doi.org/10.1071/wr9940175.
Testo completoAbstract (sommario):
Surveys aimed at determining the distribution and habitat of the rare and endangered western ringtail possum (Pseudocheirus occidentalis) were undertaken in south-western Australia during 1990-92. Surveys relied on sightings of animals, or their characteristic faecal pellets or dreys. Habitat descriptions were collected in areas occupied by P. occidentalis to describe the vegetation and topography. Additional information about habitat was collected at subsets of sites to reflect leaf nutrient levels (nitrogen, phosphorus and potassium) of the major food plants, and to reflect the relative senescence of vegetation communities, and their fire and fox-baiting history. The species has a patchy occurrence from the Collie River to Two Peoples Bay, occurring most commonly in coastal or near-coastal forest that includes Agonis flexuosa as a major component. The most inland population occurs at Perup and this is the only known population living in forest without A. flexuosa. Local extinction has been extensive in the inland and northern parts of the original range (as it was known about 1900) and local decline has been patchy and occurred in most decades (1900-89) in different parts of the original range. Analysis of a matrix of relative abundance and habitat variables identified two habitat parameters associated with higher abundance of P. occidentalis: higher levels of nitrogen in foliage of the major food plant and a higher degree of canopy continuity. Hollow abundance was also implicated as a covariate of relative abundance. Assessment of levels of nitrogen, potassium and phosphorus in A. flexuosa leaves indicated that occupied sites tended to have relatively high nutrient levels. The pattern of decline and persistence of populations in different habitats is discussed with respect to environmental factors considered to have changed over the last century.
50
Krauss, Siegfried L., e Janet M. Anthony. "The potential impact of mining on population genetic variation in the Banded Ironstone Formation endemic Tetratheca erubescens (Elaeocarpaceae)". Australian Journal of Botany 67, n. 3 (2019): 172. http://dx.doi.org/10.1071/bt18054.
Testo completoAbstract (sommario):
Tetratheca erubescens is a narrowly endemic species including ~6300 plants restricted to a 2-km2 distribution on the south Koolyanobbing Range Banded Ironstone Formation (BIF) in Western Australia. A key objective of the present study was to characterise population genetic variation, and its spatial structuring across the entire distribution of T. erubescens, to enable a quantification of genetic variation that may be affected by proposed mining of the BIF. In total, 436 plants (~30 at each of 14 sites) from across the entire distribution were sampled, genotyped and scored for allelic variation at 11 polymorphic microsatellite loci. Fifty-nine alleles were detected (mean alleles per locus=5.36, range 2–10), and observed heterozygosity was low to moderate and typically lower than expected heterozygosity across all loci (mean observed heterozygosity (Ho)=0.41, mean expected heterozygosity (He)=0.48). Given the restricted distribution of T. erubescens, overall genetic structuring was surprisingly strong (overall FST=0.098). A range-wide spatial autocorrelation analysis indicated a significant positive genetic correlation at distances up to 450m, largely corresponding to the scale of more-or-less continuous distribution within each of two geographic clusters. In support, a STRUCTURE analysis identified an optimal number of genetic clusters as K=2, with assignment of individuals to one of two genetic clusters corresponding with the main geographic clusters. The genetic impact of proposed mining on T. erubescens was assessed on the basis of identifying plants within the proposed mine footprint (all plants from 4 of 14 sites). Repeating analyses of genetic variation after removal of these samples, and comparing to the complete dataset adjusted for sample size, resulted in the loss of one (very rare: overall frequency=0.001) allele (i.e. 58 of 59 alleles (98.3%) were recovered). All other parameters of genetic variation (mean Na, Ne, I, Ho, He, F) were unaffected. Consequently, although up to 22% of all plants fall within the mine footprint and, therefore, may be lost, <2% of alleles detected will be lost, and other genetic parameters remained unaffected. Although these results suggest that the proposed mining will result in a negligible impact on the assessed genetic variation and its spatial structuring in T. erubescens, further research on impacts to, and management of, quantitative genetic variation and key population genetic processes is required.