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991.
Pietro Brandmayr Roberto Pizzolotto Giorgio Colombetta Tullia Zetto 《Journal of Insect Conservation》2009,13(2):231-243
The carabid beetle species assemblages (14 sample sites) of a 238 ha urban oak forest in Trieste, Italy, studied in 1983–84
with pitfall traps, were compared with an historic list of 57 species hand collected by entomologists in the same forest before
it was logged in 1944.Trap data have been improved by hand collections to get a species list as complete as the historic one.
Multivariate analysis was used to group the sites (14 plus the historic list) into three assemblages of brooks, clearings
and forests. After the Second World War logging, the secondary ecological succession resulted in a lower species number, with
a trend to a new equilibrium. Some important forest specialists, such as Laemostenus venustus, have been lost. Human pressure and recolonisation by carabids are still occurring. The in situ extinction of ground beetles
near the end of the last century reached values between 57 and 64% of the species historically recorded. Consequently, urgent
restoration measures are required for waterside habitats, forest and land management, to maintain small open areas or clearings.
The study of carabid species assemblages and habitat affinities seems a useful tool for adaptive management of forests affected
by human activities, because changes in carabid species number and type can be easily related to human disturbance. 相似文献
992.
Oaks host the richest fauna of saproxylic insect in Europe. We studied habitat preferences of two beetle families, Buprestidae
and Cerambycidae, by rearing the beetles from standardised oak timber baits. Species density was higher in the understorey
than in the canopy; and in sun-exposed baits if within the understorey. Insolation was the most important factor affecting
the composition of reared assemblages (explaining ca. 30% of variation in the data), followed by vertical stratum (ca. 10%).
Local dead wood volume had no effect. The high preference for sun-exposed wood located near the ground suggests that: (i)
open-canopy woodlands had to be rather common in temperate Europe; (ii) oak-utilising xylophages would benefit from restoration
of management practices such as coppicing or woodland pasture; (iii) the policy of increasing dead wood volume in commercial
forests is principally correct, but its success will depend on dead wood location within the forests. 相似文献
993.
In agricultural landscapes, linear habitats, such as hedgerows at field margins increase structural connectivity among forest
patches, potentially providing dispersal corridors for forest herbs. The spatial structure of linear habitats, however, also
results in edge effects and perturbations that can influence the individual and population performance of forest plants. This
study compares the stage structure and components of growth and reproduction of 14 Trillium grandiflorum populations in hedgerows and forests. Hedgerow Trillium tended to grow faster and, when mature, produced more flowers and more ovules per flowers than forest Trillium, a pattern possibly associated to differences in nutrients and light availability between the two habitats. Seed production
and germination rate, however, did not differ between hedgerows and forests. At the population level, seedlings and juveniles
were proportionally less abundant in hedgerows than in forests. Although well-established plants can thrive in hedgerows,
reduced recruitment may eventually limit the capacity to establish new populations and therefore hamper migration along hedgerow-corridors.
Considering the strategies by which plants persist in linear habitats becomes particularly relevant at a time when species
are expected to be much in need of dispersal corridors because of climatic stress. 相似文献
994.
The development of patterned mosaic landscapes: an overview 总被引:1,自引:0,他引:1
The articles in this special issue review what is known about the development of wetlands in landscapes and of patterns in
various kinds of wetlands around the world with an emphasis on wetlands with treed patches (tree islands) like the Okavango
Delta and the Everglades. Wetlands with treed patches have much in common with their terrestrial counterparts in arid regions.
Both are mosaic landscapes in which the patches of trees are distributed in a non-random fashion in a matrix of herbaceous
vegetation. In these landscapes, the treed patches are both biogeochemical and biodiversity hotspots. They are biogeochemical
hotspots because treed patches preferentially acquire nutrients and other limited resources, like water in arid regions. They
are biodiversity hotspots because treed patches are habitats with environmental and structural characteristics very different
from those of the herbaceous matrix in which they are found. Consequently, treed patches attract and support populations of
many plant and animal species that otherwise would not be found in the area. Studies and simulation models of arid mosaic
landscapes have generated a number of hypotheses about the structure and functions of mosaic landscapes, most of which have
yet to be tested, especially in wetland mosaic landscapes. 相似文献
995.
Microorganisms play an important role in the geobiocycling of arsenic element. However, little is known about the bacteria
involved in this process in oceanic environments. In this report, arsenite-resistant bacteria were detected in deep-sea sediments
on the Southwest Indian Ridge. From arsenite enriched cultures, 54 isolates were obtained, which showed varied tolerance to
arsenite of 2–80 mM. Phylogenetic analysis based on 16S rRNA showed that they mainly belonged to Proteobacteria and Actinobacteria.
Denaturing gradient gel electrophoresis revealed that Microbacterium esteraromaticum was the dominant member in the arsenite enriched communities, and this was reconfirmed by 16S rRNA gene library analyses.
Thus, M. esteraromaticum showed highest resistant to arsenite among the detected bacteria. These results indicate that there are quite diverse bacteria
of arsenite resistance inhabiting the deep sea sediment, which may play a role in the geobiocycling of arsenic element in
marine environments. 相似文献
996.
Benjamin Steinitz Yona Tabib Victor Gaba Tanya Gefen Yiftach Vaknin 《In vitro cellular & developmental biology. Plant》2009,45(1):65-71
Efficient vegetative cloning in vitro requires definition of plant growth regulator regimes for each genotype, and therefore formulation of a uniform culture protocol
for a genetically heterogeneous wild or uncultivated plant population is often impossible. The likelihood of cloning a wide
array of plant genotypes by avoiding the use of plant growth regulator(s) was explored with Moringa oleifera Lamk., Moringa stenopetala (Baker f.) Cufod, and Moringa peregrina Forssk. ex Fiori tree seedlings. Propagation was achieved by multiple shoot regeneration from the cotyledonary node of decapitated
seedlings, followed by axillary shoot growth from single node shoot segments and rooting of excised shoots. All steps were
accomplished on basal Murashige and Skoog medium without plant growth regulator supplements. The results revealed competence
for generation of multiple shoots from cotyledonary node tissue, stimulated by repeated shoot harvest, in seedlings of all
three tree species. Tens of plants per seedling were regenerated in about 4 mo from culture initiation. In a given species
clone size was seedling-dependent, which presumably stems from genotypic variability among seedlings in regeneration ability
in vitro. By this means the laborious search for a plant growth regulator regime suitable for organogenesis induction and adapted
per genotype became redundant, and biodiversity of the seed germplasm could be maintained. The approach ideally suits establishment
of clones of wild plants of endangered species, like those of the Moringaceae, species with high ability for producing supplementary
shoots, and without the need to add plant growth regulators, including the rooting stage. 相似文献
997.
Yang Zou Xiaoyun Jia Wen-Zhi Wang Shiqiang Li Qing-Peng Kong Yong-Gang Yao 《Biochemical and biophysical research communications》2010,399(2):179-185
LHON is one of the most common and primary causes of acute blindness in young male adults. Over 95% of LHON cases are caused by one of the three primary mutations (m.11778G>A, m.14484T>C, and m.3460G>A). In contrast to these genetically diagnosed LHON patients, there are many patients with clinical features of LHON but without the three primary mutations, and these patients have been insufficiently analyzed. We reported 10 suspected Chinese LHON families without the three primary mutations. The overall penetrance (53.4%) in these families is significantly higher than in those families with m.11778G>A (33.3%) or m.3460G>A (25.6%). Complete mtDNA genome sequencing of the 10 families showed that they belonged to different haplogroups and all identified variants (excluding m.12332A>G in mt-tRNALeu) were previously reported. Eight of 12 private non-synonymous variants in the probands are located in the MT-ND1 and MT-ND5 genes, which is substantially higher than that of individuals from general Chinese populations. Comparison of the private variants in the 10 families and in 10 randomly selected mtDNAs from general Chinese populations using resampling simulation strategy further confirmed this pattern. Our results suggest that the MT-ND1 and MT-ND5 genes are mutational hotspots for Chinese families with suspected LHON lacking the common primary mutations. Variants m.3736G>A (p.V144I) in family Le1235 and m.10680G>A (p.A71T) in Le1107 can be the pathogenic mutations for LHON. 相似文献
998.
Summary Many well‐known methods are available for estimating the number of species in a forest community. However, most existing methods result in considerable negative bias in applications, where field surveys typically represent only a small fraction of sampled communities. This article develops a new method based on sampling with replacement to estimate species richness via the generalized jackknife procedure. The proposed estimator yields small bias and reasonably accurate interval estimation even with small samples. The performance of the proposed estimator is compared with several typical estimators via simulation study using two complete census datasets from Panama and Malaysia. 相似文献
999.
Two new thick‐tail scorpions in the genus Parabuthus Pocock, 1890 are described from the gravel plains of the Central Namib Desert, Namibia: Parabuthus glabrimanus sp. nov. ; Parabuthus setiventer sp. nov. The two new species occupy discrete distributional ranges, allopatric with the closely related species Parabuthus gracilis Lamoral, 1979 and Parabuthus nanus Lamoral, 1979. The distributions of the four species are mapped and a key provided for their identification. Revised diagnoses are provided for P. gracilis and P. nanus. The two new species are added to a previously published morphological character matrix for Parabuthus species and their phylogenetic positions determined in a reanalysis of Parabuthus phylogeny. Parabuthus setiventer sp. nov. is found to be the sister species of P. nanus, whereas P. glabrimanus sp. nov. is sister to a monophyletic group comprising P. gracilis, P. nanus, and P. setiventer sp. nov. The discovery of two new scorpion species endemic to the Central Namib gravel plains contributes to a growing body of evidence that this barren and desolate region is a hotspot of arachnid species richness and endemism. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 673–710. 相似文献
1000.
ABSTRACT. We discovered a free‐living peritrich ciliate with outstanding features in the River Rhine. Its morphology and 18S rRNA gene sequence were studied with standard methods. Apocarchesium arndti n. sp. has several peculiarities. (i) There are ordinary zooids, macrozooids, and microzooids, which form a hemispherical rosette on a discoidal base, the stalk dish, locking the ~18 μm wide and up to 2 mm long, spirally contracting colony stalk. (ii) The stalk myoneme is connected only to the microzooids. (iii) A rosette contains up to 50 zooids not connected to each other but individually attached to the stalk dish with the scopula. (iv) The ordinary zooids are epistylidid, trumpet‐shaped (~6:1 length:width), about 180 × 30 μm in size, and have an ellipsoidal macronucleus subapically between oral cavity and dorsal side. (v) The myoneme system of the zooids, which can contract individually, forms a tube‐like structure in the narrow posterior half of the cell. (vi) The silverline pattern belongs to the transverse‐striate type. (vii) The oral apparatus is of usual structure, with kinety 1 of peniculus 3 distinctly shortened proximally. (viii) The 18S rRNA places A. arndti n. sp. as a distinct lineage near Vorticella and Carchesium. These data are used to provide an improved diagnosis of the genus Apocarchesium. Features (i)–(iii) and the molecular data indicate that Apocarchesium could be the type genus of a new peritrich family. 相似文献