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Species Able (species + able)
Selected AbstractsCalifornia annual grass invaders: the drivers or passengers of change?JOURNAL OF ECOLOGY, Issue 5 2010Janneke HilleRisLambers Summary 1.,The dominance of invasive species is often assumed to reflect their competitive superiority over displaced native species. However, invasive species may be abundant because of their greater tolerance to anthropogenic impacts accompanying their introduction. Thus, invasive species can either be the drivers or passengers of change. 2.,We distinguish between these two possibilities in California grasslands currently dominated by Mediterranean annuals (exotics) and subjected to livestock grazing since European settlement. We focused on native annual grasses and forbs, an understudied species-rich component of the California flora, and Mediterranean annual grasses, currently dominant and among the first non-native plants introduced to the area. 3.,We established a field experiment with fenced and unfenced blocks in a cattle pasture. We measured concentrations of limiting resources (nitrogen, phosphorus, light and soil moisture) in monoculture plots as an index of competitive ability (i.e. R*). We then quantified grazing impacts on biomass and seed production in grazed vs. ungrazed monoculture plots. Finally, we measured biomass and seed production of each species competing in mixture plots, in the presence and absence of grazers. 4.,We found that native and exotic species did not differ in R* indices of competitive ability, i.e. concentrations of limiting resources in ungrazed native monoculture plots did not differ from concentrations in ungrazed exotic monoculture plots. By contrast, exotic annuals suffered less from grazing than native annuals, perhaps reflecting their longer evolutionary history with cattle grazing. Consistent with these results, native and exotic annuals were equally abundant in ungrazed mixtures, but exotic species overwhelmingly dominated grazed mixtures. 5.,Species able to draw down nitrogen and light to lower levels in monocultures (i.e. those with lower R* values) dominated biomass and seeds in mixed plots without grazers. However, R* did not predict the relative abundance of species in grazed plots. Moreover, the relative abundance of species in mixtures did not correlate with grazing impacts on their monocultures, implying that grazing alters inter-specific competitive dynamics. 6.,Synthesis. We demonstrate that the displacement of native annuals by Mediterranean annual grasses in California may largely have been driven by cattle grazing. [source] FUNGI AND PATULIN IN APPLES AND THE ROLE OF PROCESSING ON PATULIN LEVELS IN JUICES: A STUDY ON NATURALLY CONTAMINATED APPLESJOURNAL OF FOOD SAFETY, Issue 2 2010JULIANE ELISA WELKE ABSTRACT The purpose of this study was to determine the predominant fungal species, including toxigenic strains, patulin levels in apples used for juice production and in produced juices. The possibility of use of apple highly contaminated with patulin to produce juice with lower patulin levels than the limit permitted by Codex Alimentarius was also checked. Sixteen lots of apples and juices were analyzed. The most prevalent fungal population was Penicillium spp. (93%) followed by the Aspergillus spp. (3.5%) and the Rhizopus spp. (3.5%). The mycoflora of apples was composed mainly of species that produce patulin. P. expansum was identified as the most frequently isolated species (66%). Species able to produce patulin were P. expansum and P. griseofulvum. Patulin levels in apples from cold storage ranged from 254.6 to 653.4 µg/kg. Apple juice processing caused average reduction of 95% in patulin levels. Patulin levels ranged from 14.3 to 46.7 µg/L in apple juices. In all samples were found patulin levels lower than the limit of 50 µg/L considered acceptable by the Codex Alimentarius Commission. PRACTICAL APPLICATIONS This study was performed to define the mycoflora of apples and patulin levels in apples that were used for juice production. This approach is useful to evaluate the quality of apples and the effect of processing on patulin to determine if the toxin level can be managed through postharvest procedures. Besides, information about patulin levels in juices is important to contribute for establishing national regulation. [source] Pre-infection events in non-nodulating species of African AcaciaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2000L. A. Harrier Non-nodulation occurs sporadically throughout the family Leguminosae, the genus Acacia is unusual as there are a range of species which are consistently non-nodulating, but which are closely related to species able to form nodules. A comparative study of these and coexisting related nodulating species has been made to establish whether the non-nodulating species exhibited any pre-infection characteristics which are typical of their nodulating counterparts. The non-nodulating species did not form any nodule-like structures, but exhibited pre-infection characteristics such as rhizobial attachment similar to that of their nodulating counterparts. The root exudate of nodulating A. polyacantha contained stimulatory compounds which aided binding of rhizobia to the roots of the non-nodulating species and nodulation was completely inhibited when A. polyacantha was co-cultured with a non-nodulating species. [source] Bioactive Isoflavones in Functional Foods: The Importance of Gut Microflora on BioavailabilityNUTRITION REVIEWS, Issue 6 2003Nicola J. Turner B.Sc.Tech Isoflavones present in soy may have risk and benefits to human health. Human gut microflora have been shown to exert metabolic activities on isoflavones, which influences bioavailability and bioactivity. Absorption of isoflavones is likely to occur in the small intestine where there is a diverse range of microfloral species able to hydrolyze conjugated isoflavones, releasing the bioactive aglycone for absorption or further metabolism and reconjugation. The identification of gut microbes that metabolize isoflavone aglycones is not well established. Such information may lead to a better understanding of the bioavailability of isoflavones in functional foods. [source] Phylogeography of the Iberian populations of Mioscirtus wagneri (Orthoptera: Acrididae), a specialized grasshopper inhabiting highly fragmented hypersaline environmentsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009JOAQUÍN ORTEGO Phylogeographic studies from western Palaearctic have generally focused on species able to disperse and track their emerging suitable habitats after the last ice age. However, data on species whose biogeographical histories differ from this bulk of Palaearctic fauna are scarce. This is clearly the case of some specialized organisms inhabiting inland hypersaline environments, which are likely to have had a wider distribution range during the late Tertiary and may have persisted through the Pleistocene to the present day only constituting relict populations. In this study, we use partial sequences from two mitochondrial genes [16S rRNA (16S) and cytochrome oxidase subunit II (COII)] to investigate the phylogeography of the Iberian populations of Mioscirtus wagneri (Orthoptera: Acrididae), a specialized grasshopper exclusively inhabiting hypersaline low grounds. Our results show that M. wagneri exhibits a marked phylogeographical structure, forming three main clades which correspond with populations located in north-east, central,south-east and south-west Iberia. These geographical areas did not share any haplotype, indicating that gene flow between them is absent. Nested clade analyses revealed that these lineages have probably evolved in allopatry and data on sequence divergence suggest population fragmentation from the Early Pleistocene. Overall, these results provide a broader perspective on the contribution of historical climate/geological events to biogeographical patterns of organisms currently forming relict populations of great conservation concern. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 623,633. [source] | ||||||||||