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31.
Eduardo de la Peña Martijn Vandegehuchte Dries Bonte Maurice Moens 《Plant and Soil》2008,310(1-2):113-120
Among the root-feeding nematodes that accumulate in the rhizosphere of grasses in European dunes, the genus Pratylenchus is of special relevance given its diversity and distribution. Although different species of Pratylenchus have been reported in dune grasses, the specificity towards dune plants, a fundamental aspect of the biology of the species, has hitherto not been studied. Two inoculation experiments using different combinations of grasses and nematodes were performed. The multiplication and the effect on plant growth of P. dunensis and P. brzeskii, two species which only occur in dune areas was compared with that of P. penetrans, a broad host-range species. The three Pratylenchus spp. could multiply under all hosts; however, there was a clear host-dependent response. The species-specific response observed might account for the shift of Pratylenchus spp. detected in the field. Although, a negative effect on the growth of A. arenaria was demonstrated for the three nematode species, different densities were needed to observe the same effects in plant biomass which point at nematode-specific tolerance. While the typical dune species needed very high densities to produce damage, P. penetrans needed very few specimens. The results obtained indicate that species with similar feeding adaptations show very different multiplication abilities on co-occurring hosts, an aspect that is usually overlooked for belowground herbivores in natural systems. The obtained results might suggest a coevolutionary relationship between specific nematode species and Ammophila arenaria. 相似文献
32.
Dries Knapen Guy Knaepkens Lieven Bervoets Martin I. Taylor Marcel Eens Erik Verheyen 《Conservation Genetics》2003,4(2):129-140
In this study, we aimed to delineateevolutionarily significant units (ESUs) andmanagement units (MUs) for the Europeanbullhead in Flanders (Belgium). Therefore, wedetermined the genetic interrelationshipsbetween 11 bullhead populations, using lengthvariation at 7 polymorphic microsatellite lociand sequence variation in the d-loop of themitochondrial DNA (mtDNA). Despite therelatively small geographical scale of ourstudy, the analysis of the d-loop sequencesshows that the Flemish bullhead populationscontain 3 haplotype groups, which can beassigned to 3 previously described EuropeanmtDNA clades. Because of the importantdifferences between these clades, they may bedefined as evolutionarily significant units,which should be managed separately. Analysis ofmicrosatellite data reveals very high degreesof isolation between populations, with theexception of 3 pairwise comparisons whichinvolved adjacent populations. Our data suggestthat the 3 haplotype groups probably qualify asESUs, as they show phylogeographicdifferentiation for mtDNA variants as well assignificant divergence of allele frequencies atnuclear loci. However, one of these units,limited to a single population, may be ofCentral European origin. All populations of theScheldt basin meet the criteria for MUrecognition, since significantly differentmicrosatellite allele frequencies as well asprivate alleles are found. In contrast, geneticdifferentiation among the 3 populations of theMeuse basin is very low. 相似文献
33.
Maricel Alvarez Dries Huygens Erick Olivares Isabel Saavedra Miren Alberdi Eduardo Valenzuela 《Physiologia plantarum》2009,136(4):426-436
Drought stress conditions (DC) reduce plant growth and nutrition, restraining the sustainable reestablishment of Nothofagus dombeyi in temperate south Chilean forest ecosystems. Ectomycorrhizal symbioses have been documented to enhance plant nitrogen (N) and phosphorus (P) uptake under drought, but the regulation of involved assimilative enzymes remains unclear. We studied 1-year-old N. dombeyi (Mirb.) Oerst. plants in association with the ectomycorrhizal fungi Pisolithus tinctorius (Pers.) Coker & Couch. and Descolea antartica Sing. In greenhouse experiments, shoot and root dry weights, mycorrhizal colonization, foliar N and P concentrations, and root enzyme activities [glutamate synthase (glutamine oxoglutarate aminotransferase (GOGAT), EC 1.4.1.13-14), glutamine synthetase (GS, EC 6.3.1.2), glutamate dehydrogenase (GDH, EC 1.4.1.2-4), nitrate reductase (NR, EC 1.6.6.1), and acid phosphomonoesterase (PME, EC 3.1.3.1-2)] were determined as a function of soil-water content. Inoculation of N. dombeyi with P. tinctorius and D. antartica significantly stimulated plant growth and increased plant foliar N and P concentrations, especially under DC. Ectomycorrhizal inoculation increased the activity of all studied enzymes relative to non-mycorrhizal plants under drought. We speculate that GDH is a key enzyme involved in the enhancement of ectomycorrhizal carbon (C) availability by fuelling the tricarboxylic acid (TCA) cycle under conditions of drought-induced carbon deficit. All studied assimilative enzymes of the ectomycorrhizal associations, involved in C, N, and P transfers, are closely interlinked and interdependent. The up-regulation of assimilative enzyme activities by ectomycorrhizal fungal root colonizers acts as a functional mechanism to increase seedling endurance to drought. We insist upon incorporating ectomycorrhizal inoculation in existing Chilean afforestation programs. 相似文献
34.
Nathalie Sibille Xavier Hanoulle Fanny Bonachera Dries Verdegem Isabelle Landrieu Jean-Michel Wieruszeski Guy Lippens 《Journal of biomolecular NMR》2009,43(4):219-227
Adding the 13C labelled 2-keto-isovalerate and 2-oxobutanoate precursors to a minimal medium composed of 12C labelled glucose instead of the commonly used (2D, 13C) glucose leads not only to the 13C labelling of (I, L, V) methyls but also to the selective 13C labelling of the backbone Cα and CO carbons of the Ile and Val residues. As a result, the backbone (1H, 15N) correlations of the Ile and Val residues and their next neighbours in the (i + 1) position can be selectively identified in HN(CA) and HN(CO) planes. The availability of a selective HSQC spectrum corresponding
to the sole amide resonances of the Ile and Val residues allows connecting them to their corresponding methyls by the intra-residue
NOE effect, and should therefore be applicable to larger systems. 相似文献
35.
Semi-natural habitat is extremely vulnerable to habitat fragmentation and degradation since its socio-economic value has decreased substantially during the last century in most parts of Europe. We evaluated the relative effects of habitat fragmentation and local environmental conditions on population structure and reproductive performance of the long-lived corm geophyte Colchicum autumnale in 17 highly fragmented populations. Habitat isolation did not affect patch occupancy, population structure or plant performance. In contrast, population size and local environment strongly affected population structure and reproductive performance. Densities of all life stages increased with increasing population size. Large populations also showed a higher reproductive performance and a larger proportion of new recruits. Relationships with local growth conditions pointed towards the importance of an open grassland sward for flower and fruit set and the presence of microsites for successful sexual recruitment. These results suggest that the distribution of C. autumnale consists of an assemblage of basically unconnected populations that are remnants of formerly larger populations. This is in accordance with the species' ability to grow clonally, allowing long-term persistence under deteriorating conditions that occurred during a long period of habitat fragmentation. In conclusion, our results indicate that local habitat and population size are more important than habitat fragmentation (i.e. calcareous grassland isolation and surface area) and argue in favour of a management that is primarily focused on local habitat restoration. This is preferentially accomplished by reintroducing grazing practices, complemented by regular setback of spontaneous succession towards forest. 相似文献
36.
Sara L Goodacre Oliver Y Martin Dries Bonte Linda Hutchings Chris Woolley Kamal Ibrahim CF George Thomas Godfrey M Hewitt 《BMC biology》2009,7(1):32-8
Background
Dispersal plays a key role in shaping biological and ecological processes such as the distribution of spatially-structured populations or the pace and scale of invasion. Here we have studied the relationship between long-distance dispersal behaviour of a pest-controlling money spider,Erigone atra, and the distribution of maternally acquired endosymbionts within the wider meta-population. This spider persists in heterogeneous environments because of its ability to recolonise areas through active long-distance airborne dispersal using silk as a sail, in a process termed 'ballooning'. 相似文献37.
Background
Male killing endosymbionts manipulate their arthropod host reproduction by only allowing female embryos to develop into infected females and killing all male offspring. Because the resulting change in sex ratio is expected to affect the evolution of sex-specific dispersal, we investigated under which environmental conditions strong sex-biased dispersal would emerge, and how this would affect host and endosymbiont metapopulation persistence. 相似文献38.
Hans Jacquemyn Rein Brys Dries Adriaens Olivier Honnay Isabel Roldán-Ruiz 《Conservation Genetics》2009,10(1):161-168
Due to societal changes and altered demands for firewood, the traditional forest management of coppicing has been largely
abandoned. As a result, many forest herbs that are specifically adapted to regular opening of the canopy, have suffered significant
declines in abundance, and the remaining populations of these species often tend to be small and isolated. Reduced population
sizes and pronounced spatial isolation may cause loss of within-population genetic diversity and increased between-population
differentiation through random genetic drift and inbreeding. In this study, we investigated genetic diversity and genetic
structure of 15 populations of the food-deceptive orchid Orchis mascula using AFLP markers. Within-population genetic diversity significantly increased with increasing population size, indicating
genetic impoverishment in small populations. Genetic differentiation, on the other hand, was rather low (ΦST = 0.083) and there was no significant relationship between genetic and geographic distances, suggesting substantial gene
flow within the study area. However, strong differences in levels of within-population diversity and among-population differentiation
were found for populations located in forests that have been regularly coppiced and populations found in forests that were
neglected for more than 50 years and that were totally overgrown by shrubs. Our data thus indicate that a lack of coppicing
leads to decreased genetic diversity and increased differentiation in this orchid species, most likely as a result of genetic
drift following demographic bottlenecks. From a conservation point of view, this study combined with previous results on the
demography of O. mascula in relation to forest management illustrates the importance of coppicing in maintaining viable populations of forest herbs
in the long-term. 相似文献
39.
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