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131.
F. Widdel 《Archives of microbiology》1987,148(4):286-291
Sulfate-reducing bacteria with oval to rod-shaped cells (strains AcRS1, AcRS2) and vibrio-shaped cells (strains AcRM3, AcRM4, AcRM5) differing by size were isolated from anaerobic marine sediment with acetate as the only electron donor. A vibrio-shaped type (strain AcKo) was also isolated from freshwater sediment. Two strains (AcRS1, AcRM3) used ethanol and pyruvate in addition to acetate, and one strain (AcRS1) grew autotrophically with H2, sulfate and CO2. Higher fatty acids or lactate were never utilized. All isolates were able to grow in ammonia-free medium in the presence of N2. Nitrogenase activity under such conditions was demonstrated by the acetylene reduction test. The facultatively lithoautotrophic strain (AcRS1), a strain (AcRS2) with unusually large cells (2×5 m), and a vibrio-shaped strain (AcRM3) are described as new Desulfobacter species, D. hydrogenophilus, D. latus, and D. curvatus, respectively. 相似文献
132.
Why are there so many species of bumble bees at Dungeness? 总被引:3,自引:0,他引:3
PAUL H. WILLIAMS 《Botanical journal of the Linnean Society. Linnean Society of London》1989,101(1):31-44
WILLIAMS, P. H., 1989. Why are there so many species of bumble bees at Dungeness? Dungeness is unique in the British Isles in that it has more species of bumble bees than any other locality. Three ideas about what governs the number of species at a locality are examined by locking at patterns of flower visits at Dungeness in comparison with those at Shoreham, a species-poor locality also in Kent. The species of bumble bees that are present at Dungeness but absent from Shoreham show no association in their distributions among 2 km grid-squares in Kent with the species of food-plants that they prefer at Dungeness, nor is there any correlation between the diversity of bees and diversity of food-plants at Dungeness and Shoreham. From the information available, Dungeness is most likely to have more species of bumble bees because it has a particularly high density of the more nectar-rich flowers that bumble bees can use. Bumble bees feed most profitably from deep flowers because these contain more nectar than shallow flowers, although direct access to deeper flowers is ultimately limited by the length of each bee's proboscis. The distribution of worker proboscis lengths among species in the species-pool in Kent is clumped about a median of 7.9 mm. The best foraging conditions for the maximum number of species should be provided when flowers of similar depths are present in sufficiently large numbers for all foragers to make near-optimal flower choices. Although there is no difference in median between the distributions of the bees' proboscis lengths and the depths of the flowers they use at Dungeness, at Shoreham the flower depths used are shorter than the proboscis lengths. Among the food-plants at Dungeness, high densities of Teucrium scorodonia and Echium vulgare are likely to be especially important. 相似文献
133.
Carl D. Schlichting 《Oecologia》1989,78(4):496-501
Summary Three species of Phlox (Polemoniaceae) were grown in 6 greenhouse treatments. A variety of traits were recorded and the correlations among them were computed for each treatment. The phenotypic correlations between characters are significantly altered when plants are grown under different environmental conditions. These changes in correlation structure result from the differential phenotypic plasticity of traits. Partial correlations between flower production and other traits are also environment-dependent. Such changes can alter the intensity of, and possibly the response to, selection on traits correlated with fitness in natural plant populations. 相似文献
134.
P. S. Jourdan E. D. Earle M. A. Mutschler 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(2):271-279
Summary Somatic hybridization between Brassica oleracea ssp. botrytis (cauliflower, 2n=18), carrying the Ogura (R1) male-sterile cytoplasm and B. napus (2n= 38), carrying a male-fertile, atrazine-resistant (ATR) cytoplasm, yielded three hybrids (2n=56) and six cauliflower cybrids (2n=18), which were selected for resistance to the herbicide in vitro. The hybrids and cybrids were male fertile and self-compatible. They contained both chloroplasts and mitochondria from the ATR cytoplasm. We found no evidence for mtDNA recombination in any of the regenerated plants. Selfed progeny of the B. oleracea atrazine-resistant cybrids were evaluated for tolerance to the herbicide in the field. Resistant plants exposed to 0.56–4.48 kg/ha (0.5–4.0 pounds/acre) atrazine in the soil showed no damage at any herbicide level, whereas plants of a susceptible alloplasmic line were severely damaged at the lowest level of herbicide application and killed at all higher levels. These atrazine-resistant cauliflower may have potential horticultural use, especially in fields where atrazine carry over is a serious problem. 相似文献
135.
A. A. Jaradat 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(5):653-656
Summary The diversity of two sympatrically distributed barley species (Hordeum vulgare L. and Hordeum spontaneum C. Koch.) has been assessed for 7 morphometric and 13 qualitative traits. Phenotypically, Hordeum vulgare was more stable than Hordeum spontaneum for all morphometric traits; this is a reflection of domestication and selection. The overall diversity indexes were 0.546±0.125 and 0.502±0.113 for Hordeum vulgare and Hordeum spontaneum, respectively (P=0.095). However, Hordeum spontaneum expressed a higher level of diversity for most qualitative traits. The observed similarity for a number of diversity indexes is probably due to gene flow between the two species. 相似文献
136.
H. V. Cornell 《Evolutionary ecology》1989,3(1):64-76
Summary Endophagous folivores, which are concealed inside leaf tissue for much of their life cycle, or which live externally but feed internally, should be more successful on heavily defended plants than ectophagous species. This is because endophages are more facile at feeding selectively and can manipulate tissue development to avoid physical and chemical defenses and to enhance nutrition. As a result, endophage-ectophage ratios should increase on more heavily defended hosts. This pattern will likely be strengthened by negative asymmetrical interactions with ectophages and pathogens, which may displace endophages from lightly defended hosts. The hypothesis predicts that endophages should be particularly abundant in resource-poor habitats which seem to support a preponderance of heavily defended hosts. Although data do not yet exist for a rigorous test, several observed cases where endophage distributions seem biased toward heavily defended hosts are at least consistent with the hypothesis. Plant defense levels may have little influence on the total number of herbivores associated with a host, but I suggest that guild structure can be profoundly altered. 相似文献
137.
Patterns of feeding ecology among the living macaques conform poorly with recognized phyletic distinctions within the genus
because there is an important ecological division which cross-cuts phyletic groupings. This division, between weed species
and non-weed species, is based on the differing abilities of macaques to tolerate and even prosper in close association with
human settlements. Based on available information about their ecology in the wild, we tentatively assign macaque species to
these two categories. Finally, we consider the implications of our argument for scenarios of the initial spread of the macaques. 相似文献
138.
139.
Classification and ordination of macroinvertebrate assemblages to predict stream acidity in upland Wales 总被引:2,自引:2,他引:0
Macroinvertebrates were collected from riffles at 104 sites in upland Wales during April and July 1984. Species assemblages were ordinated by DECORANA, classified by TWINSPAN and related to stream chemistry and other environmental factors using correlation and multiple discriminant analysis. DECORANA axis 1 was most strongly correlated with pH and aluminium concentration whilst axis 2 correlated with stream gradient and flow. Four TWINSPAN site groups established in each season were also principally related to pH and aluminium concentration, and reflected overall taxon-richness; differences between groups were most apparent during spring, when catchment forest cover and taxon-richness were also related. A dichotomous key based on indicator species was established for each season with the coleopteran Hydraena gracilis Germar and the Ephemeroptera, including Baetis rhodani Pictet, important indicators at Level 1. We propose that these indicator systems may be used for the rapid detection and assessment of acid waters throughout Wales, and that the methodology is applicable generally. 相似文献
140.
Changes in epilithic algal communities colonizing introduced substrata were determined in a stream polluted with oil refinery
effluent at Digboi (Assam, India). The number of algal taxa was reduced but the growth of blue-green algae, particularly two
species ofOscillatoria, was encouraged. Epilithic biomass (as chlorophylla) also declined at polluted stations. The algal community of the upstream station was markedly different from the community
occurring just after the confluence of effluent; however, the differences were gradually reduced downstream, indicating improvement
in water quality. Of the various criteria tested for possible relationships with the level of pollutants, species richness,
Shannon diversity and biomass showed significant relationships. The study demonstrates the usefulness of algal criteria for
monitoring oil pollution in running waters. 相似文献