scholarly journals Flower visitation by honey possums (Tarsipes rostratus) in a coastal banksia heathland infested with the plant pathogen Phytophthora cinnamomi

2013 ◽  
Vol 35 (2) ◽  
pp. 166 ◽  
Author(s):  
Shannon J. Dundas ◽  
Patricia A. Fleming ◽  
Giles E. St J. Hardy
Keyword(s):  
Plant Pathogen ◽  
Conservation Management ◽  
Phytophthora Cinnamomi ◽  
Pollen Grains ◽  
Floristic Diversity ◽  
Vegetation Composition ◽  
Flower Visitation ◽  
South West ◽  
Potential Impact ◽  
A Site

The honey possum (Tarsipes rostratus) is a tiny (7–10 g) obligate nectarivore endemic to south-west Western Australia that relies on high floristic diversity for year-round nectar and pollen resources. We investigated flower visitation by honey possums at a site in the presence of the plant pathogen Phytophthora cinnamomi by sampling pollen on the head of captured and radio-tracked individuals. The aim of the study was to identify plant species that were visited and to compare these with known susceptibility to Phytophthora to assess the potential impact of further spread of the pathogen on honey possums. Nine plant taxa were regularly identified from pollen on honey possums, including four Banksia species. Six of the nine plant taxa identified (Banksia plumosa, Adenanthos cuneatus, Calothamnus gracilis, B. brunnea, B. nutans, B. tenuis) were most frequently visited by honey possums, each making up >20% of pollen grains for at least one season. Five of the nine plant taxa are known to be susceptible to Phytophthora, which substantially changes vegetation composition in its wake. The inevitable spread of Phytophthora is postulated to result in the localised loss of resources for honey possums and is a concern for on-going conservation management.

scholarly journals Distribution and diversity of Phytophthora across Australia

2017 ◽  
Vol 23 (2) ◽  
pp. 150 ◽  
Author(s):  
Treena I. Burgess ◽  
Diane White ◽  
Keith M. McDougall ◽  
Jeff Garnas ◽  
William A. Dunstan ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Conservation Management ◽  
Phytophthora Cinnamomi ◽  
Environmental Dna ◽  
Phytophthora Species ◽  
Native Vegetation ◽  
New Techniques ◽  
Future Studies ◽  
Isolation Methods ◽  
Potential Impact

The introduction and subsequent impact of Phytophthora cinnamomi within native vegetation is one of the major conservation issues for biodiversity in Australia. Recently, many new Phytophthora species have been described from Australia’s native ecosystems; however, their distribution, origin, and potential impact remain unknown. Historical bias in Phytophthora detection has been towards sites showing symptoms of disease, and traditional isolation methods show variable effectiveness of detecting different Phytophthora species. However, we now have at our disposal new techniques based on the sampling of environmental DNA and metabarcoding through the use of high-throughput sequencing. Here, we report on the diversity and distribution of Phytophthora in Australia using metabarcoding of 640 soil samples and we compare the diversity detected using this technique with that available in curated databases. Phytophthora was detected in 65% of sites, and phylogenetic analysis revealed 68 distinct Phytophthora phylotypes. Of these, 21 were identified as potentially unique taxa and 25 were new detections in natural areas and/or new introductions to Australia. There are 66 Phytophthora taxa listed in Australian databases, 43 of which were also detected in this metabarcoding study. This study revealed high Phytophthora richness within native vegetation and the additional records provide a valuable baseline resource for future studies. Many of the Phytophthora species now uncovered in Australia’s native ecosystems are newly described and until more is known we need to be cautious with regard to the spread and conservation management of these new species in Australia’s unique ecosystems.

scholarly journals R-STIPPLED MAIZE AS A TRANSPOSABLE ELEMENT SYSTEM

Genetics ◽  
1984 ◽  
Vol 107 (3) ◽  
pp. 477-488
Author(s):  
W M Williams ◽  
K V Satyanarayana ◽  
J L Kermicle
Keyword(s):  
Transposable Element ◽  
Pollen Grains ◽  
Linkage Phase ◽  
Element System ◽  
In Trans ◽  
A Site

ABSTRACT The I-R element at the R locus destabilizes kernel pigmentation giving the variegated pattern known as stippled (R-st). In trans linkage phase with R-st the element was shown to act as a modifier of stippled, intensifying seed spotting in parallel with effects of the dominant linked modifier M-st. Presence of I-R in the genome was, therefore, shown to be detectable as a modifier of R-st. When this test was used, new modifiers resembling M-st were often detected following mutations of R-st to the stable allele R-sc. Such mutations evidently occurred by transposition of I-R away from the R locus to a site where it was identifiable as a modifier. M-st may be such a transposed I-R. Analysis of mutations to R-sc during the second (sperm-forming) mitosis in pollen grains showed that some of the transposed I-R elements were linked with R, whereas others assorted independently. Their strengths varied from barely discernible to a level equal to M-st. Overreplication frequently accompanied transposition at the sperm-forming mitosis, leading to transposed I-R elements in both the mutant and nonmutant sperm.

scholarly journals Are Reproductive Traits Related to Pollen Limitation in Plants? A Case Study from a Central European Meadow

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 640
Author(s):  
Michael Bartoš ◽  
Štěpán Janeček ◽  
Petra Janečková ◽  
Eliška Chmelová ◽  
Robert Tropek ◽  
...  
Keyword(s):  
Pollen Limitation ◽  
Abiotic Factors ◽  
Pollen Grains ◽  
Reproductive Traits ◽  
Biodiversity Loss ◽  
Plant Reproduction ◽  
Landscape Fragmentation ◽  
Global Changes ◽  
A Site ◽  
Relationship Of

The deficiency of pollen grains for ovule fertilization can be the main factor limiting plant reproduction and fitness. Because of the ongoing global changes, such as biodiversity loss and landscape fragmentation, a better knowledge of the prevalence and predictability of pollen limitation is challenging within current ecological research. In our study we used pollen supplementation to evaluate pollen limitation (at the level of seed number and weight) in 22 plant species growing in a wet semi-natural meadow. We investigated the correlation between the pollen limitation index (PL) and floral traits associated with plant reproduction or pollinator foraging behavior. We recorded significant pollen limitation for approximately 41% of species (9 out of 22 surveyed). Seven species had a significant positive response in seed production and two species increased in seed weight after pollen supplementation. Considering traits, PL significantly decreased with the number of pollinator functional groups. The relationship of PL with other examined traits was not supported by our results. The causes of pollen limitation may vary among species with regard to (1) different reproductive strategies and life history, and/or (2) temporary changes in influence of biotic and abiotic factors at a site.

Pollen morphology of Myrtaceae from the south-west Pacific area

1956 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
KM Pike
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
South American ◽  
The South ◽  
African Species ◽  
West Pacific ◽  
South West ◽  
The Family ◽  
Characteristic Features ◽  
Pacific Area

The pollen grains of 300 species of 71 genera of the family Myrtaceae have been examined and their characteristic features summarized in tabular form. The investigation has been mainly concerned with those species that occur in the south-west, Pacific area, particularly Australia. For comparative purposes, the pollen morphology of a limited number of South American and two South African species has been included. The significance of pollen characters for distinguishing genera and species within the family is discussed. In some instances pollen morphology has provided additional evidence for the classification of certain species as suggested by taxonomists. A provisional key to pollen grains of the genera examined has been included.

Quantification of the susceptibility of the native flora of the South-West Botanical Province, Western Australia, to Phytophthora cinnamomi

2004 ◽  
Vol 52 (4) ◽  
pp. 435 ◽  
Author(s):  
B. L. Shearer ◽  
C. E. Crane ◽  
A. Cochrane
Keyword(s):  
Western Australia ◽  
National Park ◽  
Phytophthora Cinnamomi ◽  
Natural Environments ◽  
The South ◽  
Irreversible Damage ◽  
Eucalyptus Marginata ◽  
Native Flora ◽  
South West ◽  
Wide Range

This study compares, for the first time, variation in estimates of susceptibility of native flora to Phytophthora cinnamomi Rands among four databases and proposes an estimate of the proportion of the flora of the South-West Botanical Province of Western Australia that is susceptible to the pathogen. Estimates of the susceptibility of south-western native flora to P. cinnamomi infection were obtained from databases for Banksia woodland of the Swan Coastal Plain, jarrah (Eucalyptus marginata Donn. ex Smith) forest, the Stirling Range National Park and Rare and Threatened Flora of Western Australia. For the woodland, forest and national park databases, hosts were naturally infected in uncontrolled diverse natural environments. In contrast, threatened flora were artificially inoculated in a shadehouse environment. Considerable variation occurred within taxonomic units, making occurrence within family and genus poor predictors of species susceptibility. Identification of intra-specific resistance suggests that P. cinnamomi could be having a strong selection pressure on some threatened flora at infested sites and the populations could shift to more resistant types. Similar estimates of the proportion of species susceptible to P. cinnamomi among the databases from the wide range of environments suggests that a realistic estimate of species susceptibility to P. cinnamomi infection in the south-western region has been obtained. The mean of 40% susceptible and 14% highly susceptible equates to 2284 and 800 species of the 5710 described plant species in the South-West Botanical Province susceptible and highly susceptible to P. cinnamomi, respectively. Such estimates are important for determining the cost of disease to conservation values and for prioritising disease importance and research priorities. P. cinnamomi in south-western Australia is an unparalleled example of an introduced pathogen with a wide host range causing immense irreversible damage to unique, diverse but mainly susceptible plant communities.

Studies on cepaea, IV. Climate and selection of banding morphs in cepaea from the climatic optimum to the present day

1968 ◽  
Vol 253 (789) ◽  
pp. 483-498 ◽  
Keyword(s):  
Iron Age ◽  
Systematic Change ◽  
Anglo Saxon ◽  
Closely Related Species ◽  
Area Effect ◽  
Cepaea Nemoralis ◽  
South West ◽  
Area Effects ◽  
A Site ◽  
Selection Of

A number of samples of subfossil Cepaea nemoralis and hortensis from sites in southern Britain of archaeological interest, ranging in date from about 4500 b .c . to Romano-British and Anglo-Saxon, have been scored for frequency of the major banding morphs, and compared with present-day samples taken on each site or as near to it as these species could be found. In C. nemoralis there is a significant decrease of unbandeds from pre-iron Age samples to the corresponding ones for the present day, but no indication of systematic change from Iron Age samples to the present day. Spread banded also shows changes from pre-iron Age samples to present-day ones, but very little change from the early Iron Age to the present day. The smaller samples of C. hortensis available give no sign of a trend although there is much change from pre-iron Age times to the present; Iron Age samples and the corresponding present-day ones do not show the relative constancy of composition seen in C. nemoralis —as usual these two very closely related species are behaving differently. At the present day there is evidence (experimental and distributional) that the frequencies of banding morphs of C. nemoralis are affected by climate, unbandeds and mid-bandeds being favoured by better summers than those normal in Britain at present. The available evidence, from pollen analysis and other sources, of changes in the climate of southern Britain in the last 6500 years suggests that the observed differences in morph frequencies can be related to known climatic changes, in agreement with present-day evidence. One area effect (south-west M arlborough Downs) has contracted and become less intense since pre-iron Age times, as perhaps have others; in some cases a site has remained in an area effect, but the effect itself has changed. Two pairs of samples from lowland sites appear to have changed from frequencies indicating area effects in pre-iron Age times to others consistent with visual selection at the present day. Area effects seem to have been rather constant from the Iron Age to the present day.

Phytophthora cinnamomi invasion, a major threatening process to conservation of flora diversity in the South-west Botanical Province of Western Australia

2007 ◽  
Vol 55 (3) ◽  
pp. 225 ◽  
Author(s):  
B. L. Shearer ◽  
C. E. Crane ◽  
S. Barrett ◽  
A. Cochrane
Keyword(s):  
Plant Species ◽  
Plant Communities ◽  
Western Australia ◽  
Phytophthora Cinnamomi ◽  
Ex Situ ◽  
Effective Control ◽  
Susceptible Plant ◽  
The South ◽  
South West ◽  
Indirect Impacts

The invasive soilborne plant pathogen Phytophthora cinnamomi Rands is a major threatening process in the South-west Botanical Province of Western Australia, an internationally recognised biodiversity hotspot. Comparatively recent introduction of P. cinnamomi into native plant communities of the South-west Botanical Province of Western Australia since the early 1900s has caused great irreversible damage and altered successional change to a wide range of unique, diverse and mainly susceptible plant communities. The cost of P. cinnamomi infestation to community values is illustrated by examination of direct (mortality curves, changes in vegetation cover) and indirect impacts on biodiversity and ecosystem dynamics, the proportion of Threatened Ecological Communities infested, Declared Rare Flora either directly or indirectly threatened by infestation and estimates of the proportion of the native flora of the South-west Botanical Province susceptible to the pathogen. While direct impacts of P. cinnamomi have been poorly documented in the South-west Botanical Province, even less attention has been given to indirect impact where destruction of the habitat by the pathogen affects taxa not directly affected by infection. Current poor understanding and quantification of indirect impacts of P. cinnamomi through habitat destruction results in an underestimation of the true impact of the pathogen on the flora of the South-west Botanical Province. Considerable variation of susceptibility to P. cinnamomi among and within families of threatened flora and responses of taxa within the genus Lambertia show how classification within family and genus are poor predictors of species susceptibility. Within apparently susceptible plant species, individuals are resistant to P. cinnamomi infection. Intra-specific variation in susceptibility can be utilised in the long-term management of threatened flora populations and needs to be a high research priority. Current control strategies for conservation of flora threatened by P. cinnamomi integrate hygiene and ex situ conservation with disease control using fungicide. Application of the fungicide phosphite has proven effective in slowing progress of P. cinnamomi in infested, threatened communities. However, variation in plant species responses to phosphite application is a major factor influencing effective control of P. cinnamomi in native communities. A greater understanding of the mechanisms of action of phosphite in plant species showing different responses to the fungicide may provide options for prescription modification to increase phosphite effectiveness in a range of plant species. The range of responses to P. cinnamomi infection and phosphite application described for Lambertia taxa suggests that the genus would make an ideal model system to elucidate the mechanisms of resistance to P. cinnamomi and the effectiveness of phosphite against the pathogen.

An Iron-Age Site near Radley, Berks.

1931 ◽  
Vol 11 (4) ◽  
pp. 399-404
Author(s):  
E. Thurlow Leeds
Keyword(s):  
Iron Age ◽  
Limited Area ◽  
The South ◽  
Human Occupation ◽  
The Road ◽  
Oxford University ◽  
South West ◽  
Westerly Direction ◽  
Northern Edge ◽  
A Site

In 1928 by courteous permission of Mr. Badcock, the owner, the Oxford University Archaeological Society, under the supervision of Mr. R. T. Lattey, was able to examine a site in a field bounded on the west by the road leading from Radley village to Abingdon and on the south by a second road leading eastwards towards Radley station. There, on the wall of a disused gravelpit, holes filled with earth had produced evidence of human occupation. Exploration of some of these resulted in the discovery of a series of trenches, the relation of which to one another could not be exactly determined owing to the limited area available for investigation. One piece of trench ran with a somewhat north-easterly trend up to the northern edge of the field, with a recessed pit about 4½ ft. across at one point, while a second longer stretch, after running in a north-westerly direction for a few yards, turned almost at right angles towards the south-west, and some distance farther on, at the point where the excavations had to cease, appeared to be bending southwards.

scholarly journals Sensitivity of commercial pumpkin yield to potential decline among different groups of pollinating bees

2017 ◽  
Vol 4 (5) ◽  
pp. 170102 ◽  
Author(s):  
Sonja C. Pfister ◽  
Philipp W. Eckerter ◽  
Jens Schirmel ◽  
James E. Cresswell ◽  
Martin H. Entling
Keyword(s):  
Crop Yield ◽  
Fruit Set ◽  
Pollen Grains ◽  
Pollen Deposition ◽  
Insect Pollination ◽  
Study Region ◽  
Flower Visitation ◽  
Pollen Receipt ◽  
The Relationship ◽  
Pollinator Fauna

The yield of animal-pollinated crops is threatened by bee declines, but its precise sensitivity is poorly known. We therefore determined the yield dependence of Hokkaido pumpkin in Germany on insect pollination by quantifying: (i) the relationship between pollen receipt and fruit set and (ii) the cumulative pollen deposition of each pollinator group. We found that approximately 2500 pollen grains per flower were needed to maximize fruit set. At the measured rates of flower visitation, we estimated that bumblebees (21 visits/flower lifetime, 864 grains/visit) or honeybees (123 visits, 260 grains) could individually achieve maximum crop yield, whereas halictid bees are ineffective (11 visits, 16 grains). The pollinator fauna was capable of delivering 20 times the necessary amount of pollen. We therefore estimate that pumpkin yield was not pollination-limited in our study region and that it is currently fairly resilient to single declines of honeybees or wild bumblebees.

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