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181.
Functional equivalence in plant-animal interactions: ecological and evolutionary consequences 总被引:4,自引:0,他引:4
Regino Zamora 《Oikos》2000,88(2):442-447
182.
Cesc Múrria Núria Bonada Miquel A. Arnedo Carmen Zamora‐Muñoz Narcís Prat Alfried P. Vogler 《Journal of Biogeography》2012,39(9):1621-1632
Aim The evolutionary processes structuring the composition of communities remain unclear due to the complexity of factors active at various spatial and temporal scales. Here, we conducted ecological and evolutionary analyses of communities of caddisflies in the genus Hydropsyche (Insecta: Trichoptera) composed of ecomorphologically differentiated species. Location River ecosystems in the Iberian Peninsula and northern Morocco. Methods Nineteen environmental variables were assessed at 180 local study sites and species presence/absence at these sites was used to determine their ecological niche. The evolutionary framework for all 19 species of Hydropsyche encountered was generated by phylogenetic analysis of the mitochondrial cytochrome c oxidase subunit I gene and three nuclear genes: wingless, elongation factor 1‐alpha and 28S RNA. The phylogenetic tree was used: (1) to assess evolutionary niche conservatism by ecological trait correlation with the tree; and (2) to analyse the phylogenetic relatedness of community member species, at three spatial scales (local stream reaches, drainage basins, biogeographical regions). Results Ecological measurements grouped most species into either headwater, mid‐stream or lowland specialists, and traits presumably relevant to river zonation were found to be phylogenetically conservative. Species assemblages at local stream reaches were mostly mono‐ or dispecific. Species diversity increased at larger spatial scales, by adding species with non‐overlapping ecological niches at the level of river basins and by turnover of anciently differentiated lineages at the level of biogeographical regions. This indicates the effects of competition and niche filtering on community structure locally, and ancient ecological diversification and allopatric speciation, respectively, in building up the species pool at basin and biogeographical scales. Main conclusions The study demonstrates the importance of scale (grain size) in studying what determines community composition. Current ecological factors (i.e. competitive exclusion) in Hydropsyche were evident only when studying narrow local sites, while studies of assemblages at larger spatial scales instead demonstrated the roles of ecological niche differentiation, phylogenetic history of trait diversification and allopatric speciation. Increasing the grain size of investigation reveals different portions of correlated spatial and evolutionary processes. 相似文献
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185.
N. Navarro-Gonzalez M. Ugarte-Ruiz M. C. Porrero L. Zamora G. Mentaberre E. Serrano A. Mateos S. Lavín L. Domínguez 《EcoHealth》2014,11(3):333-342
Campylobacter infections are a public health concern and an increasingly common cause of food-borne zoonoses in the European Union. However, little is known about their spill-over from free-ranging livestock to sympatric wild ungulates, especially in regards to uncommon Campylobacter species. In this study, we aim to determine the prevalence of C. coli, C. jejuni and other C. spp. in game ungulates (wild boar Sus scrofa and Iberian ibex Capra pyrenaica) and free-ranging sympatric cattle in a National Game Reserve in NE Spain. Furthermore, we explore the extent to which Campylobacter species are shared among these co-habiting hosts. Faecal samples from Iberian ibex (n = 181) were negative for C. spp. By direct plating, two wild boars out of 150 were positive for C. coli (1.3%, 95% CI 0.16–4.73), and one was positive for C. jejuni (0.67%, 95% CI 0.02–3.66). The latter was predominant in cattle: 5.45% (n = 55, 95% CI 1.14–5.12), while C. coli was not isolated from this host. C. lanienae was the most frequent species in wild boar at 10% (95% CI 5.7–15.96), and one cow cohabiting with positive wild boars in the same canyon also carried C. lanienae. Four enrichment protocols (using Bolton or Preston broth combined with either mCCDA or CFA) were added for 172 samples (57 from wild boars, 55 cattle and 60 Iberian ibexes) to increase the number of isolates obtained allowing the detection of statistically significant differences. The prevalence of C. lanienae was statistically significantly higher in wild boar than in cattle (P < 0.01), but the prevalence of C. jejuni was higher in the latter (P = 0.045). These results suggest that wild boar and cattle carry their own predominant Campylobacter species, while Iberian ibex do not seem to play an important role in the epidemiology of Campylobacter. However, there is a potential spill-over of C. spp., and thus, further research is needed to elucidate the factors determining inter-species transmission. 相似文献
186.
A. Hernández J. Zamora N. González E. Salazar M.D.C. Sánchez 《Journal of applied microbiology》2009,107(2):436-442
Aim: The major objective of this study was the development of a methodology to quantify the anhydrobiotic ability of bacteria and its application to evaluate the stability of desiccated bacterial cells using the biocontrol agent Tsukamurella paurometabola C-924 as a model of anhydrobiote.
Methods and Results: Tsukamurella paurometabola C-924 was desiccated by spray-drying. Samples of desiccated cells were stored at several temperatures and viability and residual moisture were measured at different intervals of time. The term anhydrobiosis quotient (ε) was defined, and a scale of anhydrobiotic ability for classifying micro-organisms in terms of tolerance to desiccation was established (1 ≤ ε ≤ 15). The anhydrobiosis quotient was used to evaluate the stability of the anhydrobiotic cells. As a main result, changes in the anhydrobiosis quotient at several temperatures were fitted using a reparameterized Weibull model, which was found to be robust for the prediction of the stability at 4°C.
Conclusions: A novel methodology was developed to evaluate the desiccated state in bacteria. The anhydrobiosis quotient allows the quantitative estimation of the anhydrobiotic ability, and the mathematical model developed allows the prediction of the desiccated state of bacterial populations.
Significance and Impact of the Study: The new methodology could be applied in studying the anhydrobiosis state of bacterial populations as a predictive tool for industrial and environmental microbiology. 相似文献
Methods and Results: Tsukamurella paurometabola C-924 was desiccated by spray-drying. Samples of desiccated cells were stored at several temperatures and viability and residual moisture were measured at different intervals of time. The term anhydrobiosis quotient (ε) was defined, and a scale of anhydrobiotic ability for classifying micro-organisms in terms of tolerance to desiccation was established (1 ≤ ε ≤ 15). The anhydrobiosis quotient was used to evaluate the stability of the anhydrobiotic cells. As a main result, changes in the anhydrobiosis quotient at several temperatures were fitted using a reparameterized Weibull model, which was found to be robust for the prediction of the stability at 4°C.
Conclusions: A novel methodology was developed to evaluate the desiccated state in bacteria. The anhydrobiosis quotient allows the quantitative estimation of the anhydrobiotic ability, and the mathematical model developed allows the prediction of the desiccated state of bacterial populations.
Significance and Impact of the Study: The new methodology could be applied in studying the anhydrobiosis state of bacterial populations as a predictive tool for industrial and environmental microbiology. 相似文献
187.
The objectives were to test the hypothesis that exogenous prostaglandin F2α (PGF2α) temporarily restores sexual behavior of castrated boars, and to evaluate effects of PGF2α on serum hormone concentrations. At 35 d after castration, nine lean-type adult boars were randomly assigned to three treatments in a 3 × 3 latin square (with three replicates). Treatments were three doses of PGF2α doses (0, 10, and 20 mg) and three periods of treatment, with 5 d between each period. Serum testosterone (T) concentrations were non-detectable at the start of the experiment. Serum concentrations of estradiol (E2), LH, prolactin (PRL), and cortisol were unaffected (P > 0.05) by PGF2α treatment. The interval from treatment to ejaculation in boars treated with 10 mg (758 s) or 20 mg (660 s) PGF2α did not differ, but were different (P < 0.05) from control boars (>1 800 s). Ejaculation duration and false mounts differed (P < 0.05) between control boars and boars treated with 10 or 20 mg PGF2α. In conclusion, PGF2α treatment did not change serum concentrations of T, E2, LH, PRL, or cortisol, but restored sexual behavior. This restoration may have been due to an effect of PGF2α directly in specific areas of the brain, or indirectly via release of other hormones that stimulated areas in the brain that affected sexual behavior. 相似文献
188.
189.
Novel ecosystems: theoretical and management aspects of the new ecological world order 总被引:9,自引:1,他引:8
Richard J. Hobbs Salvatore Arico James Aronson Jill S. Baron Peter Bridgewater Viki A. Cramer Paul R. Epstein John J. Ewel Carlos A. Klink Ariel E. Lugo David Norton Dennis Ojima David M. Richardson Eric W. Sanderson Fernando Valladares Montserrat Vilà Regino Zamora Martin Zobel 《Global Ecology and Biogeography》2006,15(1):1-7
We explore the issues relevant to those types of ecosystems containing new combinations of species that arise through human action, environmental change, and the impacts of the deliberate and inadvertent introduction of species from other regions. Novel ecosystems (also termed 'emerging ecosystems') result when species occur in combinations and relative abundances that have not occurred previously within a given biome. Key characteristics are novelty, in the form of new species combinations and the potential for changes in ecosystem functioning, and human agency, in that these ecosystems are the result of deliberate or inadvertent human action. As more of the Earth becomes transformed by human actions, novel ecosystems increase in importance, but are relatively little studied. Either the degradation or invasion of native or 'wild' ecosystems or the abandonment of intensively managed systems can result in the formation of these novel systems. Important considerations are whether these new systems are persistent and what values they may have. It is likely that it may be very difficult or costly to return such systems to their previous state, and hence consideration needs to be given to developing appropriate management goals and approaches. 相似文献
190.
A Bonnet PO Frappart P Dehais G Tosser-Klopp F Hatey 《Reproductive biology and endocrinology : RB&E》2006,4(1):35-11
FSH, which binds to specific receptors on granulosa cells in mammals, plays a key role in folliculogenesis. Its biological
activity involves stimulation of intercellular communication and upregulation of steroidogenesis, but the entire spectrum
of the genes regulated by FSH has yet to be fully characterized. 相似文献