Orchid fruiting success is unrelated to surrounding floral resources in South Australian plant communities

2021 ◽  
Author(s):  
Irene Martín-Forés ◽  
Samantha L. Bywaters ◽  
Ben Sparrow ◽  
Greg Guerin
Keyword(s):  
South Australia ◽  
Shannon Index ◽  
Floral Resources ◽  
Individual Species ◽  
Lavandula Stoechas ◽  
Australian Plant ◽  
Orchid Pollination ◽  
Floral Density ◽  
Pollination Strategy ◽  
Pearson Correlations

To maintain recruitment in orchid populations in an ecosystem setting, we must understand how surrounding floral resources affect fruiting success. We studied fruiting success in two endemic Australian species, Diruis pardina and Glossodia major, in relation to surrounding floral resources. Diuris pardina has a visually deceptive pollination strategy via mimicry of pea flowers, attracting pollinators associated with co-flowering plants of Pultenaea. Glossodia major displays dummy anthers and has a more generalist pollination strategy. We expected fruit set of both species to positively correlate to conspecific and heterospecific floral density because orchid pollination should be enhanced by the attraction of higher densities of bees. We expected fruiting success of D. pardina to positively correlate with abundance of Pultenaea flowers. Surveying 18 plots in South Australia, we counted species, individuals and flowers of conspecifics and heterospecifics and returned to count flowers that set fruit. We conducted Pearson correlations between fruiting success and density of conspecific flowers, richness, abundance and Shannon index of surrounding floral resources and floral abundance of individual species. Fruiting success was correlated with conspecific floral density for Diuris pardina but not G. major. No relationship was found between fruiting success and heterospecific floral resources. Fruiting success of D. pardina was not correlated with abundance of Pultenaea; instead it was positively correlated with the invasive species Lavandula stoechas.

scholarly journals Monitoring change in biodiversity through composite indices

2005 ◽  
Vol 360 (1454) ◽  
pp. 243-254 ◽  
Author(s):  
S.T Buckland ◽  
A.E Magurran ◽  
R.E Green ◽  
R.M Fewster
Keyword(s):  
Survey Design ◽  
Geometric Mean ◽  
Shannon Index ◽  
Change Points ◽  
Individual Species ◽  
Composite Indices ◽  
Biodiversity Change ◽  
Technical Issues ◽  
Spatially Varying ◽  
Underlying Trend

The need to monitor trends in biodiversity raises many technical issues. What are the features of a good biodiversity index? How should trends in abundance of individual species be estimated? How should composite indices, possibly spanning very diverse taxa, be formed? At what spatial scale should composite indices be applied? How might change-points—points at which the underlying trend changes—be identified? We address some of the technical issues underlying composite indices, including survey design, weighting of the constituent indices, identification of change-points and estimation of spatially varying time trends. We suggest some criteria that biodiversity measures for use in monitoring surveys should satisfy, and we discuss the problems of implementing rigorous methods. We illustrate the properties of different composite indices using UK farmland bird data. We conclude that no single index can capture all aspects of biodiversity change, but that a modified Shannon index and the geometric mean of relative abundance have useful properties.

Dark Island heath (Ninety-mile plain, South Australia). VII. The effect of fertilizers on composition and growth, 1950-60

1963 ◽  
Vol 11 (1) ◽  
pp. 67 ◽  
Author(s):  
RL Specht
Keyword(s):  
Field Experiments ◽  
Harmful Effect ◽  
South Australia ◽  
Maximum Growth ◽  
Phosphate Fertilizer ◽  
Individual Species ◽  
Fertility Level ◽  
Vegetation Growth ◽  
Annual Grasses ◽  
Heath Community

Field experiments described in this paper analyse the effect of increase in soil fertility level on heath vegetation growing on the Makin sand. Fertilizers, P, N, Cu, and Zn, were added to raise the fertility of the plots to that of more fertile soils which, in coastal eastern and southern Australia, support a herbaceous understorey. Increased fertility did not affect germination of heath plants, but it influenced adversely the establishment of seedlings. Application of even small quantities of fertilizers (2 cwt superphosphate per acre, 2 cwt sodium nitrate per acre) greatly reduced the survival rate of all seedlings. Phosphorus fertilizer produced greatly increased growth in both surviving seedlings and mature heath plants; nitrogen together with phosphorus improved the growth of some species still further. There was great variation in the responses of individual species to fertilizers: some species showed maximum growth at 2 cwt superphosphate per acre, others at 4, others at 8 cwt per acre. The first group is dominant in the climax vegetation. Growth of the heath community was almost trebled by additions of 16 cwt superphosphate per acre. "Phosphorus toxicity" symptoms were observed in some mature heath species. Phosphate fertilizer hastened maturation and flowering in some heath seedlings which, after the addition of superphosphate, flowered some two years before the controls. This treatment also induced annual flowering a week or two earlier than on the control plots. Annual grasses, herbs, and a moss appeared and survived on all phosphorustreated plots, rarely in the unfertilized heath. Seeds of these annual species were windborne either from neighbouring farms five miles away or from adjacent plant communities. The results of these field experiments suggest that: (1) herbaceous species fail to survive on impoverished soils because of the low level of phosphorus which precludes satisfactory growth; (2) heath species are excluded from the more fertile soils firstly by some harmful effect on seedlings and secondly by competition from the more vigorous herbaceous plants in this environment. Gradually over the last 10 years heath plots fertilized with phosphorus fertilizers have shown changes towards a herbaceous sward.

Mychodea and the Mychodeaceae (Gigartinales, Rhodophyta) revisited: molecular analyses shed light on interspecies relationships in Australia’s largest endemic algal genus and family

2017 ◽  
Vol 30 (3) ◽  
pp. 230
Author(s):  
Gerald T. Kraft ◽  
Gary W. Saunders
Keyword(s):  
South Australia ◽  
Molecular Data ◽  
Individual Species ◽  
Additional Species ◽  
Marine Habitats ◽  
South Wales ◽  
Red Algal ◽  
Reproductive Material ◽  
Algal Genus ◽  
The Individual

The red algal genus Mychodea Hook.f. & Harv. is not only Australia’s largest wholly endemic macroalgal genus, it and the family Mychodeaceae (of which it is the sole member) appear to be the largest completely endemic algal genus and family from any continental landmass in the world. Kraft’s 1978 morpho-taxonomic monograph credited Mychodea with 11 species varyingly distributed between Geraldton, Western Australia, south and eastward across the coasts of South Australia, Victoria and Tasmania, and northwards into southern New South Wales. Dismissed or discounted was every former extra-Australian attribution of the genus. In the over 40 years since completion of the research, further explorations of marine habitats in Australia have uncovered additional species, and the application of molecular-assisted taxonomic and phylogenetic methodologies has now allowed a substantial refinement of Mychodea systematics. We here document 19 Mychodea species, for 16 of which we have molecular data that support inferences of probable species relationships. To the 11 species treated by Kraft we now add 4 that are recently discovered, resurrect 2 that were synonymised with a third species in his 1978 work, and treat 2 species-level Western Australian entities that remain unnamed for lack of sufficient reproductive material. Mychodea is characterised by elaborate vegetative structures and some of the most complex fertilisation, diploidisation and embryogenesis processes of any red alga, which we detail and illustrate. Distinguishing features of the individual species are highlighted, some of which are particularly unusual.

scholarly journals Spectral Deconvolution for Dimension Reduction and Differentiation of Seagrasses: Case Study of Gulf St. Vincent, South Australia

2019 ◽  
Vol 11 (13) ◽  
pp. 3695 ◽  
Author(s):  
Charnsmorn Hwang ◽  
Chih-Hua Chang ◽  
Michael Burch ◽  
Milena Fernandes ◽  
Tim Kildea
Keyword(s):  
Water Column ◽  
Spectral Reflectance ◽  
South Australia ◽  
Reflectance Spectra ◽  
Individual Species ◽  
Site Location ◽  
Coastal Habitat ◽  
Suspended Particulate ◽  
Derivative Analysis ◽  
Spectral Profiles

Seagrasses are a vulnerable and declining coastal habitat, which provide shelter and substrate for aquatic microbiota, invertebrates, and fishes. More accurate mapping of seagrasses is imperative for their sustainability but is hindered by the lack of data on reflectance spectra representing the optical signatures of individual species. Objectives of this study are: (1) To determine distinct characteristics of spectral profiles for sand versus three temperate seagrasses (Posidonia, Amphibolis, and Heterozostera); (2) to evaluate the most efficient derivative analysis method of spectral reflectance profiles for determining benthic types; and to assess the influences of (3) site location and (4) the water column on spectral responses. Results show that 566:689 and 566:600 bandwidth ratios are useful in separating seagrasses from sand and from detritus and algae, respectively; first-derivative reflectance spectra generally is the most efficient method, especially with deconvolution analyses further helping to reveal and isolate 11 key wavelength dimensions; and differences between sites and water column composition, which can include suspended particulate matter, both have no effect on endmembers. These findings helped develop a spectral reflectance library that can be used as an endmember reference for remote sensing, thereby providing continued monitoring, assessment, and management of seagrasses.

scholarly journals Evaluating competition for forage plants between honey bees and wild bees in Denmark

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0250056
Author(s):  
Claus Rasmussen ◽  
Yoko L. Dupont ◽  
Henning Bang Madsen ◽  
Petr Bogusch ◽  
Dave Goulson ◽  
...  
Keyword(s):  
Honey Bees ◽  
Conservation Status ◽  
Niche Overlap ◽  
Floral Resources ◽  
Individual Species ◽  
Plant Interactions ◽  
Operational Parameters ◽  
Wild Bees ◽  
Forage Plants ◽  
Wild Bee

A recurrent concern in nature conservation is the potential competition for forage plants between wild bees and managed honey bees. Specifically, that the highly sophisticated system of recruitment and large perennial colonies of honey bees quickly exhaust forage resources leading to the local extirpation of wild bees. However, different species of bees show different preferences for forage plants. We here summarize known forage plants for honey bees and wild bee species at national scale in Denmark. Our focus is on floral resources shared by honey bees and wild bees, with an emphasis on both threatened wild bee species and foraging specialist species. Across all 292 known bee species from Denmark, a total of 410 plant genera were recorded as forage plants. These included 294 plant genera visited by honey bees and 292 plant genera visited by different species of wild bees. Honey bees and wild bees share 176 plant genera in Denmark. Comparing the pairwise niche overlap for individual bee species, no significant relationship was found between their overlap and forage specialization or conservation status. Network analysis of the bee-plant interactions placed honey bees aside from most other bee species, specifically the module containing the honey bee had fewer links to any other modules, while the remaining modules were more highly inter-connected. Despite the lack of predictive relationship from the pairwise niche overlap, data for individual species could be summarized. Consequently, we have identified a set of operational parameters that, based on a high foraging overlap (>70%) and unfavorable conservation status (Vulnerable+Endangered+Critically Endangered), can guide both conservation actions and land management decisions in proximity to known or suspected populations of these species.

Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

1970 ◽  
Vol 28 ◽  
pp. 328-329
Author(s):  
J. R. Ruby ◽  
R. F. Dyer ◽  
R. G. Skalko ◽  
R. F. Gasser ◽  
E. P. Volpe
Keyword(s):  
Germ Cells ◽  
Rana Pipiens ◽  
Comparative Morphology ◽  
Dense Material ◽  
Individual Species ◽  
Microscope Examination ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Cytoplasmic Side ◽  
Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

Modelling ecosystem adaptation and dangerous rates of global warming

2019 ◽  
Vol 3 (2) ◽  
pp. 221-231 ◽  
Author(s):  
Rebecca Millington ◽  
Peter M. Cox ◽  
Jonathan R. Moore ◽  
Gabriel Yvon-Durocher
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Diffusion Rate ◽  
Individual Species ◽  
Genetic Evolution ◽  
Rates Of Change ◽  
Rapid Climate Change ◽  
Warming Climate ◽  
Intraspecies Competition ◽  
High Trait

Abstract We are in a period of relatively rapid climate change. This poses challenges for individual species and threatens the ecosystem services that humanity relies upon. Temperature is a key stressor. In a warming climate, individual organisms may be able to shift their thermal optima through phenotypic plasticity. However, such plasticity is unlikely to be sufficient over the coming centuries. Resilience to warming will also depend on how fast the distribution of traits that define a species can adapt through other methods, in particular through redistribution of the abundance of variants within the population and through genetic evolution. In this paper, we use a simple theoretical ‘trait diffusion’ model to explore how the resilience of a given species to climate change depends on the initial trait diversity (biodiversity), the trait diffusion rate (mutation rate), and the lifetime of the organism. We estimate theoretical dangerous rates of continuous global warming that would exceed the ability of a species to adapt through trait diffusion, and therefore lead to a collapse in the overall productivity of the species. As the rate of adaptation through intraspecies competition and genetic evolution decreases with species lifetime, we find critical rates of change that also depend fundamentally on lifetime. Dangerous rates of warming vary from 1°C per lifetime (at low trait diffusion rate) to 8°C per lifetime (at high trait diffusion rate). We conclude that rapid climate change is liable to favour short-lived organisms (e.g. microbes) rather than longer-lived organisms (e.g. trees).

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