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Darwell C.T.,University of Reading | Darwell C.T.,Syracuse University | Al-Beidh S.,Royal Horticultural Society | Cook J.M.,University of Reading | Cook J.M.,University of Western Sydney
BMC Evolutionary Biology | Year: 2014

Background: Symbiotic relationships have contributed to major evolutionary innovations, the maintenance of fundamental ecosystem functions, and the generation and maintenance of biodiversity. However, the exact nature of host/symbiont associations, which has important consequences for their dynamics, is often poorly known due to limited understanding of symbiont taxonomy and species diversity. Among classical symbioses, figs and their pollinating wasps constitute a highly diverse keystone resource in tropical forest and savannah environments. Historically, they were considered to exemplify extreme reciprocal partner specificity (one-to-one host-symbiont species relationships), but recent work has revealed several more complex cases. However, there is a striking lack of studies with the specific aims of assessing symbiont diversity and how this varies across the geographic range of the host.Results: Here, we use molecular methods to investigate cryptic diversity in the pollinating wasps of a widespread Australian fig species. Standard barcoding genes and methods were not conclusive, but incorporation of phylogenetic analyses and a recently developed nuclear barcoding gene (ITS2), gave strong support for five pollinator species. Each pollinator species was most common in a different geographic region, emphasising the importance of wide geographic sampling to uncover diversity, and the scope for divergence in coevolutionary trajectories across the host plant range. In addition, most regions had multiple coexisting pollinators, raising the question of how they coexist in apparently similar or identical resource niches.Conclusion: Our study offers a striking example of extreme deviation from reciprocal partner specificity over the full geographical range of a fig-wasp system. It also suggests that superficially identical species may be able to co-exist in a mutualistic setting albeit at different frequencies in relation to their fig host's range. We show that comprehensive sampling and molecular taxonomic techniques may be required to uncover the true structure of cryptic biodiversity underpinning intimate ecological interactions. © 2014 Darwell et al.; licensee BioMed Central Ltd. Source

Blanusa T.,Royal Horticultural Society | Blanusa T.,University of Reading | Fantozzi F.,University of Siena | Monaci F.,University of Siena | Bargagli R.,University of Siena
Urban Forestry and Urban Greening | Year: 2015

Holm oak (Quercus ilex), a widespread urban street tree in the Mediterranean region, is widely used as biomonitor of persistent atmospheric pollutants, especially particulate-bound metals. By using lab- and field-based experimental approaches, we compared the leaf-level capacity for particles' capture and retention between Q. ilex and other common Mediterranean urban trees: Quercus cerris, Platanus×hispanica, Tilia cordata and Olea europaea. All applied methods were effective in quantifying particulate capture and retention, although not univocal in ranking species performances. Distinctive morphological features of leaves led to differences in species' ability to trap and retain particles of different size classes and to accumulate metals after exposure to traffic in an urban street. Overall, P.×hispanica and T. cordata showed the largest capture potential per unit leaf area for most model particles (Na+ and powder particles), and street-level Cu and Pb, while Q. ilex acted intermediately. After wash-offexperiments, P.×hispanica leaves had the greatest retention capacity among the tested species and O. europaea the lowest. We concluded that the Platanus planting could be considered in Mediterranean urban environments due to its efficiency in accumulating and retaining airborne particulates; however, with atmospheric pollution being typically higher in winter, the evergreen Q. ilex represents a better year-round choice to mitigate the impact of airborne particulate pollutants. © 2015 Elsevier GmbH. Source

Blanusa T.,Royal Horticultural Society | Blanusa T.,University of Reading | Vaz Monteiro M.M.,University of Reading | Fantozzi F.,University of Siena | And 3 more authors.
Building and Environment | Year: 2013

Green roof plants alter the microclimate of building roofs and may improve roof insulation. They act by providing cooling by shading, but also through transpiration of water through their stomata. However, leaf surfaces can become warmer when plants close the stomata and decrease water loss in response to drying substrate (typically associated with green roofs during summers), also reducing transpirational cooling. By using a range of contrasting plant types (Sedum mix - an industry green roof 'standard', Stachys byzantina, Bergenia cordifolia and Hedera hibernica) we tested the hypothesis that plants differ in their 'cooling potential'. We firstly examined how leaf morphology influenced leaf temperature and how drying substrate altered that response. Secondly, we investigated the relationship between leaf surface temperatures and the air temperatures immediately above the canopies (i.e. potential to provide aerial cooling). Finally we measured how the plant type influenced the substrate temperature below the canopy (i.e. potential for building cooling). In our experiments Stachys outperformed the other species in terms of leaf surface cooling (even in drying substrate, e.g. 5 °C cooler compared with Sedum), substrate cooling beneath its canopy (up to 12 °C) and even - during short intervals over hottest still periods - the air above the canopy (up to 1 °C, when soil moisture was not limited). We suggest that the choice of plant species on green roofs should not be entirely dictated by what survives on the shallow substrates of extensive systems, but consideration should be given to supporting those species providing the greatest eco-system service potential. © 2012 Elsevier Ltd. Source

Chen W.,Agriculture and Agri Food Canada | Djama Z.R.,Agriculture and Agri Food Canada | Coffey M.D.,University of California at Riverside | Martin F.N.,U.S. Department of Agriculture | And 5 more authors.
Phytopathology | Year: 2013

Most Phytophthora spp. are destructive plant pathogens; therefore, effective monitoring and accurate early detection are important means of preventing potential epidemics and outbreaks of diseases. In the current study, a membrane-based oligonucleotide array was developed that can detect Phytophthora spp. reliably using three DNA regions; namely, the internal transcribed spacer (ITS), the 5' end of cytochrome c oxidase 1 gene (cox1), and the intergenic region between cytochrome c oxidase 2 gene (cox2) and cox1 (cox2-1 spacer). Each sequence data set contained ≈250 sequences representing 98 described and 15 undescribed species of Phytophthora. The array was validated with 143 pure cultures and 35 field samples. Together, nonrejected oligonucleotides from all three markers have the ability to reliably detect 82 described and 8 undescribed Phytophthora spp., including several quarantine or regulated pathogens such as Phytophthora ramorum. Our results showed that a DNA array containing signature oligonucleotides designed from multiple genomic regions provided robustness and redundancy for the detection and differentiation of closely related taxon groups. This array has the potential to be used as a routine diagnostic tool for Phytophthora spp. from complex environmental samples without the need for extensive growth of cultures. © 2013 The American Phytopathological Society. Source

Alexander P.D.,Royal Horticultural Society | Bragg N.C.,Horticultural Development Company
Acta Horticulturae | Year: 2014

2011 saw the publication of a White Paper in which UK government reaffirmed its commitment to seeing a reduction in peat used in UK horticulture. The Department for Environment, Food and Rural Affairs, the Government department responsible for this issue, established a Task Force made up of representatives from across the horticultural industry (including manufacturers, growers, retailers and NGOs) to develop an agreed way forward. It was suggested by the Task Force Chairman that the issue could be broken down into 12 specific (but interlinked) projects. This paper describes the progress to date by one of these Task Force projects (Project 4). Project 4 endeavours to develop a system by which growing media materials from different sources can be assessed and compared in terms of their sustainability. The first steps of this process were to defining and qualify "sustainability". This was achieved by identifying a number of criteria against which we would be able to assess materials (e.g., habitat damage in production, energy and water use). For each criterion, consideration was given to what it is we are trying to prevent/encourage. From this a decision tree emerged that allows users to distinguish better from poorer (in terms of sustainability) growing media sources. The accuracy of the assessment was improved by the inclusion of measurable factors in each criterion. Eight criteria have been identified allowing each material to be scored on a 0 (bad) to 20 (good) scale for each of the criteria and at the end of the decision tree, each outcome can be attributed a score. Discussion continues with regards to how best to present the information. Presenting a total score for each growing media would require the criteria to be weighted. Obviously different people will regard criteria differently in terms of their environmental values complicating the process of weighting scores. On reflection it may be more useful to simply provide the scores for individual criteria to give users as much information as possible to inform their decision making process. It is important to remember that this scheme is simply meant to give any horticultural user better information with regards to sourcing and comparing specific materials in order to make a more informed decision regarding the source-specific material they choose. This scheme has not been designed to rule in or out certain source-specific materials. One potential additional benefit of this scheme is that the horticultural users may be able to improve the "sustainability" within their supply chain by challenging suppliers to match or better their competitors in relation to specific criteria. Source

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