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Showing papers by "Adrian C. Newton published in 2004"


Journal ArticleDOI
TL;DR: Results indicate that all four native tree species can be established successfully both within forest fragments and in neighboring agricultural areas, emphasizing the scope for forest restoration and the importance of accurate speciessite matching.
Abstract: The cloud forests of Mexico have been degraded and severely fragmented, and urgently require restoration. However, progress with restoration has been constrained by a lack of information concerning the seedling ecology of native tree species. An experiment was therefore conducted to assess the influence of different environmental factors on the seedling survival and growth of four native tree species (Fagus grandifolia var. mexicana, Carpinus caroliniana, Symplocos coccinea, and Quercus acutifolia). The seedlings were established on three sites, in two contrasting environments: inside forest fragments and on adjacent agricultural land. Highly significant differences were recorded in seedling survival and growth among sites, environments, species, and interactions between these factors. Highest survival was recorded for Quercus, which uniquely among the four species displayed the same survival percentage inside and outside the forest. Survival of the other species was higher inside the forest. In contrast, growth rates of all four species were higher outside the forest. The most important cause of mortality outside the forest was desiccation, although significant seedling predation was also observed on two sites. Results indicate that all four species can be established successfully both within forest fragments and in neighboring agricultural areas, emphasizing the scope for forest restoration. However, the interactions observed between species, sites, and environments highlight the importance of accurate speciessite matching if optimum rates of growth and survival are to be obtained. Quercus spp. have great potential for establishment on agricultural sites.

85 citations


Journal ArticleDOI
TL;DR: An array of genetic markers in a population analysis elucidate the hybrid origins of the Arran whitebeams Sorbus arranensis and S. pseudofennica and indicate the products of multiple and ongoing evolutionary events.
Abstract: Understanding the processes that have given rise to polyploid hybrid taxa is central to our understanding of plant evolution. In this study, we use an array of genetic markers in a population analysis to elucidate the hybrid origins of the Arran whitebeams Sorbus arranensis and S. pseudofennica, two woody plant taxa endemic to the Isle of Arran, Scotland. It has been proposed that S. arranensis was derived by hybridization between S. aucuparia and S. rupicola, and that subsequent hybridization between S. arranensis and S. aucuparia gave rise to S. pseudofennica. Analyses of species-specific isozyme, nuclear intron and chloroplast DNA markers confirm the proposed origin of S. arranensis, and indicate that S. aucuparia was the female parent in the hybridization. Analysis of microsatellite markers suggests that there have been at least three origins of S. arranensis on Arran. Microsatellite markers also support the proposed hypothesis for the origin of S. pseudofennica, and indicate at least five hybrid origins of this taxon. In total, three multilocus genotypes of S. arranensis and eight of S. pseudofennica were detected on Arran and multilocus genotypic diversity levels Hg were 0.09 and 0.63, respectively. Genetic differentiation (thetaST) values based on multilocus genotypes are substantial (0.344 and 0.470 for S. arranensis and S. pseudofennica, respectively) implying limited seed flow among populations. These results indicate that the endemic Sorbus taxa on Arran are the products of multiple and ongoing evolutionary events. This information must be incorporated into management policies for their future conservation.

67 citations


Journal ArticleDOI
TL;DR: It is suggested that an unexpectedly high degree of genetic variation exists within Mexican beech, and this variation should be considered in developing the conservation strategy that is urgently required if extinction of this taxon is to be prevented.
Abstract: Fagus grandifolia var. mexicana(Fagaceae) is a Mexican endemic tree, currently threatened with extinction. In order to assess the level and structure of genetic variation in four remaining populations, leaf samples were analysed using random amplified polymorphic DNA (RAPD) and cpDNA PCR-RFLP markers. A sample of the more widespread congener, F. grandifoliavar. grandifolia from the USA was also analysed for comparison. Thirty-three polymorphic RAPD bands were produced using 18 10-mer primers. AMOVA of RAPD data indicated significant (P < 0.002) population differentiation, with 15.6% of variation recorded between Mexican populations. PCR-RFLP analysis enabled three cpDNA haplotypes to be identified, denoted types A, B, and C. Types A and B were each restricted to an individual Mexican population, whereas Type C was fixed for two Mexican populations, and the population from the USA. Within-population genetic variation, quantified as percentage polymorphic bands, Shannon's Diversity Index and Nei's gene diversity measure, was found to be lower in Mexican populations than in that from the USA, and was positively related to population size. These results suggest that an unexpectedly high degree of genetic variation exists within Mexican beech, and this variation should be considered in developing the conservation strategy that is urgently required if extinction of this taxon is to be prevented.

42 citations


Journal ArticleDOI
01 Nov 2004-Heredity
TL;DR: Molecular marker analysis of three trees from Arran with an unusual leaf morphology indicates that they are the product of sexual reproduction by S. pseudofennica, and may originate from hybridisation with S. aucuparia.
Abstract: The Arran whitebeams Sorbus arranensis and S. pseudofennica are two endemic woody plant taxa that have evolved on Arran through hybridisation. S. arranensis is a triploid hybrid between the widespread diploid S. aucuparia and the rare tetraploid S. rupicola. S. pseudofennica is a tetraploid formed by crossing between S. arranensis and S. aucuparia. In order to determine the mating systems of the two endemic species six maternal trees of each taxon together with 10–12 of their seed offspring were scored for their phenotype at three microsatellite loci and one nuclear intron locus. All seeds of S. arranensis were identical in phenotype to their maternal parents. In S. pseudofennica, 17.5% of all seeds differed in marker phenotype from their maternal parent. The proportion of seed with nonmaternal phenotypes varied significantly among maternal trees of S. pseudofennica. The results suggest that the triploid S. arranensis is an obligate apomict, whereas the tetraploid S. pseudofennica is a facultative apomict. Molecular marker analysis of three trees from Arran with an unusual leaf morphology indicates that they are the product of sexual reproduction by S. pseudofennica, and may originate from hybridisation with S. aucuparia. This research demonstrates that the Sorbus taxa on Arran are participants in an active evolutionary process generating novel biodiversity. Conservation programmes for these taxa should aim to preserve this evolutionary process rather than the individual taxonomic entities that it produces.

35 citations


Journal ArticleDOI
01 Mar 2004-Planta
TL;DR: Regulation of bmi sequences was investigated using salicylic acid, methyl jasmonate, ethylene, H2O2, abscisic acid, wounding and a glucan elicitor, suggesting either combinations of these stimuli, or additional stimuli, are involved in early Mla13 and mlo5 resistances.
Abstract: Suppression subtractive hybridisation was used to isolate 21 cDNAs ( bmi1- bmi21) up-regulated 1-5 h post-inoculation (hpi) in a barley ( Hordeum vulgare L. cv. Pallas) near-isogenic line (NIL) P11 ( Mla13) challenged with either avirulent or virulent isolates of Blumeria graminis f. sp. hordei. Transcriptional changes at these time-points are crucial for the Mla-mediated hypersensitive response [W.R. Bushnell and Z. Liu (1994) Physiol Mol Plant Pathol 44:389-402]. Seven sequences were up-regulated by 1 hpi, when the pathogen has formed only the primary germ tube. Some transcripts were similar to genes with a role in regulating programmed cell death in animals, including NF kappaB and oxysterol-binding protein. Moreover, bmi7, similar to rice resistance gene Xa21, was rapidly up-regulated in both compatible and incompatible interactions, but was then down-regulated by 5 hpi in the virulent interaction. Only nine of the transcripts were up-regulated in mlo5 resistance in cv. Pallas NIL P22, confirming differential pathway induction between Mla13 and mlo5. However, eight sequences up-regulated in the Mla13 response in P11 were already highly elevated in uninoculated mlo5 mutant P22, suggesting that they may be negatively regulated by wild-type Mlo. Regulation of bmi sequences was investigated using salicylic acid, methyl jasmonate, ethylene, H(2)O(2), abscisic acid, wounding and a glucan elicitor. No single stimulus up-regulated all genes, suggesting either combinations of these stimuli, or additional stimuli, are involved in early Mla13 and mlo5 resistances. Whereas H(2)O(2) up- or down-regulated 17 of the transcripts detected in Northern analyses, salicylic acid stimulated only down-regulation of 5 transcripts.

25 citations


Journal ArticleDOI
TL;DR: Winter wheat (Triticum aestivum) and winter barley (Hordeum vulgare) were grown on soil contaminated with different levels of a marked bacterial potato pathogen Erwinia carotovora ssp.
Abstract: Summary • Winter wheat (Triticum aestivum) and winter barley (Hordeum vulgare) were grown on soil contaminated with different levels of a marked bacterial potato pathogen Erwinia carotovora ssp. atroseptica (Eca) from a previous blackleg-infected potato crop, to determine whether the presence of this pathogen could affect disease development on wheat and barley. • The diseases ‘septoria leaf blotch’ and ‘powdery mildew’ on wheat (caused by Septoria tritici and Blumeria graminis f. sp. tritici, respectively) and ‘scald’ or ‘rhynchosporium’ on barley (caused by Rhynchosporium secalis) were assessed over two growing seasons, and the presence of the marked Eca strain monitored. • Wheat diseases were greater on the areas with high levels of Eca contamination than on areas with low-level contamination. Rhynchosporium on barley was not affected overall, although it decreased on the high-level contamination areas early in the season. The Eca strain was detected on the upper foliage of both wheat and barley. • Increased S. tritici symptoms in the field may be due to ‘synergistic’ interactions between the Eca and the fungal mycelium, as reported in previously published laboratory experiments. The potential importance of such fungal–bacterial interactions is discussed.

16 citations


Journal ArticleDOI
TL;DR: Reflectance from barley field trial plots was measured to determine whether it could be used as an accurate estimate of disease and yield response to fungicide, and whether this was consistent over a range of agronomic factors.
Abstract: Summary Reflectance from barley field trial plots was measured to determine whether it could be used as an accurate estimate of disease and yield response to fungicide, and whether this was consistent over a range of agronomic factors. Three trials were used to test the effects of cultivar, assessment date, fungicide and dose, different disease and fertiliser. Correlations with predominant disease and resulting yield loss were high, often better than visual disease or green leaf area measurements alone. Certain ratios of two reflectance wavelength measurements were more robust predictors than single wavelengths. Cultivar and development stage had a large influence on measurements and calibration for such morphology-based characters would be essential for practical deployment. Whilst weather conditions and solar angle restrict opportunities for usage of reflectance tools such as the‘Cropscan Radiometer', it may prove useful in crop loss assessments as an additional objective tool.

9 citations


01 Jan 2004
TL;DR: Species Conservation and Management: Case Studies as discussed by the authors is a collection of population and metapopulation models for a wide variety of species, which deal with many complexities of modeling the life history characteristics of different species in various environments, and address a variety of issues such as habitat loss, exploitation, fragmentation, diseases, pollution, habitat restoration, translocation and connectivity.
Abstract: Species Conservation and Management: Case Studies is a collection of population and metapopulation models for a wide variety of species. The chapters deal with many complexities of modeling the life history characteristics of different species in various environments, and address a variety of issues such as habitat loss, exploitation, fragmentation, diseases, pollution, habitat restoration, translocation, and connectivity. Each chapter describes how a species' life history characteristics are incorporated into the model, and how the results can be used for its conservation and management. The book includes a CD-ROM with a demo version of the RAMAS GIS program and data files for all the models.

4 citations


01 Jan 2004

3 citations