P. J. D. Lambshead

University of Southampton, Southampton, England, United Kingdom

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Publications (13)28.61 Total impact

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    ABSTRACT: Biodiversity assessment is the key to understanding the relationship between biodiversity and ecosystem functioning, but there is a well-acknowledged biodiversity identification gap related to eukaryotic meiofaunal organisms. Meiofaunal identification is confounded by the small size of taxa, morphological convergence and intraspecific variation. However, the most important restricting factor in meiofaunal ecological research is the mismatch between diversity and the number of taxonomists that are able to simultaneously identify and catalogue meiofaunal diversity. Accordingly, a molecular operational taxonomic unit (MOTU)-based approach has been advocated for en mass meiofaunal biodiversity assessment, but it has been restricted by the lack of throughput afforded by chain termination sequencing. Contemporary pyrosequencing offers a solution to this problem in the form of environmental metagenetic analyses, but this represents a novel field of biodiversity assessment. Here, we provide an overview of meiofaunal metagenetic analyses, ranging from sample preservation and DNA extraction to PCR, sequencing and the bioinformatic interrogation of multiple, independent samples using 454 Roche sequencing platforms. We report two examples of environmental metagenetic nuclear small subunit 18S (nSSU) analyses of marine and tropical rainforest habitats and provide critical appraisals of the level of putative recombinant DNA molecules (chimeras) in metagenetic data sets. Following stringent quality control measures, environmental metagenetic analyses achieve MOTU formation across the eukaryote domain of life at a fraction of the time and cost of traditional approaches. The effectiveness of Roche 454 sequencing brings substantial advantages to studies aiming to elucidate the molecular genetic richness of not only meiofaunal, but also all complex eukaryotic communities.
    Molecular Ecology 03/2010; 19 Suppl 1:4-20. · 6.28 Impact Factor
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    ABSTRACT: Phylogenetic reconstructions of relations within the phylum Nematoda are inherently difficult but have been advanced with the introduction of large-scale molecular-based techniques. However, the most recent revisions were heavily biased towards terrestrial and parasitic species and greater representation of clades containing marine species (e.g. Araeolaimida, Chromadorida, Desmodorida, Desmoscolecida, Enoplida, and Monhysterida) is needed for accurate coverage of known taxonomic diversity. We now add small subunit ribosomal DNA (SSU rDNA) sequences for 100 previously un-sequenced species of nematodes, including 46 marine taxa. SSU rDNA sequences for >200 taxa have been analysed based on Bayesian inference and LogDet-transformed distances. The resulting phylogenies provide support for (i) the re-classification of the Secernentea as the order Rhabditida that derived from a common ancestor of chromadorean orders Araeolaimida, Chromadorida, Desmodorida, Desmoscolecida, and Monhysterida and (ii) the position of Bunonema close to the Diplogasteroidea in the Rhabditina. Other, previously controversial relationships can now be resolved more clearly: (a) Alaimus, Campydora, and Trischistoma belong in the Enoplida, (b) Isolaimium is placed basally to a big clade containing the Axonolaimidae, Plectidae, and Rhabditida, (c) Xyzzors belongs in the Desmodoridae, (d) Comesomatidae and Cyartonema belongs in the Monhysterida, (e) Globodera belongs in the Hoplolaimidae and (f) Paratylenchus dianeae belongs in the Criconematoidea. However, the SSU gene did not provide significant support for the class Chromadoria or clear evidence for the relationship between the three classes, Enoplia, Dorylaimia, and Chromadoria. Furthermore, across the whole phylum, the phylogenetically informative characters of the SSU gene are not informative in a parsimony analysis, highlighting the short-comings of the parsimony method for large-scale phylogenetic modelling.
    Molecular Phylogenetics and Evolution 04/2007; 42(3):622-36. · 4.07 Impact Factor
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    ABSTRACT: Museums and other research organizations around the world have large numbers of formalin-fixed marine invertebrates in their collections. These have the potential to be a valuable resource for molecular ecological studies, but the development of methodologies for the molecular analysis of formalin-fixed material has been slow. In this study, a hot lysis protocol accompanied by the use of a commercial DNA extraction kit has been employed for DNA recovery from archived marine nematodes, followed by PCR amplification and sequencing. In total, 25 specimens ranging from estuarine to deep sea environments were subjected to molecular analyses. Successful amplification and sequencing of the nuclear small subunit ribosomal RNA (18S rRNA) gene was achieved in all individuals. Additionally, some estuarine nematodes were tentatively identified to genus and species using a phylogenetic approach. In the future, this technique should prove to be profitable for the genetic study of a wide range of formalin-fixed marine invertebrates.
    Zoologica Scripta 09/2006; 36(1):93 - 98. · 2.79 Impact Factor
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    ABSTRACT: Small metazoans such as marine nematodes are increasingly identified using both molecular and morphological techniques. Formalin is the preferred fixative for morphological analysis but specimens become unsuitable for molecular study due to formalin-induced modification of DNA. Nematodes fixed in ethanol work well for molecular studies but become unsuitable for taxonomy due to shrinkage. Here we show for the first time that formalin can be used as a short-term fixative (≤ 7 days) for marine nematodes, allowing both morphological and molecular work to be conducted on the same individual. No sequence ambiguities were detected in polymerase chain reaction (PCR) amplifications of 18S ribosomal DNA (rDNA) following short-term formalin preservation.
    Molecular Ecology Notes 07/2005; 5(4):965 - 968. · 2.38 Impact Factor
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    ABSTRACT: Abundance of nematode assemblages from the sediment surrounding an experimentally implanted whale carcass in the Santa Cruz Basin were investigated at 1.5 and 18 months after placement. Samples were taken at 0, 1, 3, 9 and 30 m distance away from the carcass.Abundance is positively correlated with distance from the carcass out to at least 30 m. Analyses of nematode abundance at 18 months after implantation showed a non-linear inverse pattern to that of the macrofauna implying that enhanced macrofaunal activity immediately around the carcass was decreasing nematode abundance through predation or competition. The increased nematode abundance at 30 m after 18 months may be a response to organic enrichment from the whale fall occurring where macrofaunal abundance no longer limits nematode densities.
    Deep Sea Research Part I: Oceanographic Research Papers. 05/2004;
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    ABSTRACT: Linkages across the sediment–water interface (SWI) between biodiversity and community sta-bility appear to exist but are very poorly studied. Processes by which changes in biodiversity could affect stability on the other side of the SWI include carbon transfer during feeding, decomposition of organic matter, nutrient recycling, organism recruitment and structural stabilisation of sediments. The importance of these processes will clearly vary among habitats. Direct disturbance to communities on one side of the SWI, such as created by overfishing, habitat destruction, and species invasions, has the potential to impact communities on the other side of the SWI through the many functional links. Hypotheses are proposed to suggest further areas of research to fill the large gaps in our knowledge concerning the nature and intensity of such linkages. The linkage between benthic and pelagic diversity is likely to be tighter where there is a close energetic connection between the domains, such as polar and shallow coastal waters, and where communities are dominated by selective detritivores. The quantity of carbon reserves in the sediment and the predominant mode of larval development of sediment communities probably influence the stability of below SWI communities in the face of changes in above SWI diversity. The organisms, including hyperbenthos, that are found at the SWI may be of crucial importance to the linkage and stability of above and below SWI communities.
    Biodiversity and Conservation 01/2002; 11:113-136. · 2.26 Impact Factor
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    ABSTRACT: We provide the first account of the effects of forest disturbance on species richness of nematodes in tropical forest soils, from 24 sites along gradients of disturbance and regeneration in the Mbalmayo Forest Reserve, Cameroon. Species richness was very high. Samples of 200 nematodes from individual soil cores contained a maximum of 89 and an average of 61 species; in total we recorded 431 species and approximately 194 genera. The model of Siemann et al. (1996), predicting that species richness scales as the number of individuals I 0.5, underestimates nematode diversity 4–6 fold in these samples. Over 90% of specimens cannot be assigned to known species. Although nematode species richness declined with forest disturbance, statistically significant effects were detectable only under the most extreme conditions (active slash-and-burn agriculture and complete mechanical forest clearance) and even here remained at 40% of the richness of near primary sites. Impacts on trophic structure were also small, and there were no significant changes in the maturity index (MI) (Bongers 1990) with disturbance (mean MI across all treatments was very high, at 3.58). In the light of this study, the problems of completing reliable all-taxon inventories in tropical forests are briefly discussed.
    Oecologia 07/1997; 111(4):575-582. · 3.01 Impact Factor
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    ABSTRACT: Sedimentary habitats cover most of the ocean bottom and therefore constitute the largest. single ecosystem on earth in spatial coverage, Although only a small fraction of the micro-, meio- and macroscopic benthic organisms that reside in and on sediments have been described and few estimates of total species numbers and biogeographic pattern have been attempted, there is sufficient information on a few species to suggest that sedimentary organisms significantly impact major ecological processes. Benthic organisms contribute to regulation of carbon, nitrogen, and sulfur cycling, water column processes, pollutant distribution and fate, secondary production, and transport, and stability of sediments. Linkages between groups of organisms and the level of functional redundancy is poorly known, however, there is probably substantial redundancy within groups. There is little evidence that biodiversity per se is necessary for benthic systems to contribute to ecosystem services. but because linkages are so poorly known and predictive knowledge confined to a few species, it is not presently possible to predict exactly how species loss will impact these services and ecosystem health. Thus, a precautionary approach of "assume the worst" is advised, and every effort should be made to curtail the species and genetic diversity loss resulting from fishing, pollution, habitat destruction, introduction of non-native (exotic) species, and global warming. Concurrently, scientists must take advantage of exciting, rapidly evolving technology and a rejuvenated interest in biodiversity to provide more concrete and thorough information on benthos and ecosystem processes. [KEYWORDS: Species-diversity; sea; pollution; richness; mesocosm; samples]
    Ambio. 01/1997;
  • H. M. Platt, K. M. Shaw, P. J. D. Lambshead
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    ABSTRACT: If the concepts of biological indices and biomonitoring at the multi-species level are to prove viable, then meiofauna and marine nematodes in particular should be an ideal group with which to test the hypothesis. Many attempts to assess the structure of species assemblages, such as the use of diversity indices, nematode: copepod ratios and the graphical method of log normal plots, have been shown to be theoretically unsound and/or impractical, especially for routine use by extension workers. A method of assessing shifts in dominance patterns which involves all the proportional species abundances is suggested as a better means of comparing diversity. A modified method of rapidly assessing Simpson's dominance-weighted diversity index is also advocated as being of practical use. In combination, they should enable the diversity aspect of the multi-species approach to biomonitoring to be rigorously and exhaustively evaluated.
    Hydrobiologia 09/1984; 118(1):59-66. · 1.99 Impact Factor
  • P. J. D. Lambshead, H. M. Platt, K. M. Shaw
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    ABSTRACT: A criterion for comparing diversity is offered based on dominance patterns involving all the proportional species abundances. The method is applied by plotting percentage cumulative abundance curves. This can reveal that some assemblages cannot be compared in terms of diversity or equitability and that intrinsic diversity indices cannot under these circumstances be relied upon. The behaviour and interpretation of these dominance curves under different circumstances is explored using examples from macrobenthic and marine nematode studies. Dominance curves are also compared with Sanders' rarefaction curves and the relative advantages discussed. It is recommended that these graphical methods be routinely applied to marine biological data before calculating more complex diversity or equitability indices.
    Journal of Natural History 01/1983; 17(6):859-874. · 0.78 Impact Factor
  • P. J. D. LAMBSHEAD
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    ABSTRACT: The freeliving marine nematode genus Tarvaia Allgen, 1934 (Tarvaiidae) is revised and pictorial and tabular keys to die species are given. A generic diagnosis is presented and die systematic position of the genus is briefly discussed. Tarvaia angusta Gerlach, 1953 is recorded from the west coast of Scotland and the first description of a male is given. Tarvaia jenseni sp. nov. is described from die Øresund and Tarvaia peruvensis Nichols & Musselman, 1979 is redescribed from type material.
    Zoological Journal of the Linnean Society 01/1981; 73(3):259-272. · 2.58 Impact Factor
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    ABSTRACT: Marine nematodes, which play an important role in many ecosystems, include a number of apparently cosmopolitan taxa that exhibit broad biogeographic ranges even though there is no obvious dispersal phase in their lifecycle. In this study, standard taxonomic approaches to marine nematode identification in conjunction with multivariate statistical analysis of morphometric data were compared with molecular techniques. Specimens of the marine nematode Terschellingia longicaudata that had been identified by their morphological features were investigated from a range of localities (East and West Atlantic, Bahrain, Malaysia) and habitats (estuarine, intertidal, subtidal) using molecular approaches based on the amplification and sequencing of the small subunit ribosomal RNA (18S rRNA). The study revealed that the majority of the morphologically defined T. longicaudata specimens share a single 18S rRNA sequence and apparently belong to a single taxon distributed from the British Isles to Malaysia. In addition, 18S rRNA analysis also revealed two additional sequences. One of these sequences was found in both the British Isles and Mexico, the other was recorded only from British waters. Individuals collected in Bahrain and identified from their morphology as T. longicaudata had two highly divergent 18S rRNA sequences. Separate morphological and morphometric approaches to identification of specimens from the same sites that had been formalin-preserved did not support evidence of multiple genotypes revealed previously by molecular analysis. Current taxonomy based on morphological characters detected using light-microscopy may be unable to discriminate possible species complexes. Biodiversity of marine nematodes may often be underestimated due to the presence of morphologically cryptic species complexes. High-throughput techniques such as DNA barcoding would aid in species identification but may require thorough analysis of multiple nuclear and mitochondrial molecular markers.
    Marine Biology 154(3):509-518. · 2.47 Impact Factor

Publication Stats

579 Citations
28.61 Total Impact Points

Institutions

  • 2007–2010
    • University of Southampton
      • National Oceanography Centre Southampton (NOCS)
      Southampton, England, United Kingdom
  • 1981–2007
    • Natural History Museum, London
      • Department of Zoology
      Londinium, England, United Kingdom