首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Earthworms are important soil organisms yet we have limited knowledge on the geographical distribution of species. Using data from a variety of sources representing a total of 3,941 locality records we have produced the first distribution maps of earthworm species in the British Isles The maps highlight the paucity of knowledge on this ecologically important group. A systematic approach needs to be taken to bring earthworm species data to a level comparable with other important invertebrate groups such as nematodes and isopods. Through the recent establishment of an earthworm recording scheme, the Earthworm Society of Britain, working with the Biological Records Centre and earthworm researchers across the British Isles, aim to build comprehensive distribution information for future monitoring and research purposes.  相似文献   

2.
During 1972 and 1973 the Salmonella and Shigella Reference Laboratory examined 133 strains of Shigella dysenteriae and Shigella boydii isolated from patients in England and Wales. Of those infected 89 had recently travelled abroad and a further seven had been in close contact with travellers recently returned to this country. Though these subgroups were of little numerical significance they are of considerable epidemiological interest. The increase in tourism from the British Isles to North Africa and Asia is likely to lead to an increased incidence of infections due to these organisms, both in travellers infected abroad and in their contacts within the British Isles.  相似文献   

3.
The geographical relationships of British and Irish vascular plants   总被引:19,自引:0,他引:19  
Classifications of British and Irish vascular plants into floristic elements are reviewed. Only H.C. Watson and J.R. Matthews have attempted to devise a more or less comprehensive classification, based on the British range of the species (Watson) or the European distribution (Matthews). A new classification of 1481 native species is presented, based on their range in the Northern Hemisphere. Species are classified by their occurrence in one or more major biomes (Arctic, Boreal, Temperate, Southern) and their longitudinal distribution (Oceanic, Suboceanic, European, Eurosiberian, Eurasian, Circumpolar). The distribution of species in the floristic elements is illustrated by coincidence maps for the British Isles and Europe. The British and Irish flora is dominated by Boreo-temperate, Temperate and Southern-temperate species, with the Temperate species being the most numerous. Species with continental distributions (i.e. species which are rarer than expected in western Europe) are listed; most of these are in the Boreo-temperate and Temperate elements. The floristic elements are discussed in relation to the life-form spectra, habitat preferences and altitudinal limits of the component species, and analysed in terms ol˜ Ellenberg indicator values for temperature and continentality. The new classification is compared with that of Matthews. An additional 48 species which are endemic to the British Isles are listed. The scope for extending this method of classification to other organisms and for adapting it for use outside the British Isles is discussed.  相似文献   

4.
A new taxonomic treatment of the Festuca ovina L. aggregate (Poaceae) in the British Isles. A wide range of morphological, anatomical and cytological characters was collected and analysed by a variety of methods, some taxometric. As a result nine species are recognized in the British Isles, one (F. glauca Vill.) only as a garden plant and two (F. huonii Auquier and F. armoricana Kerguélen) only in the Channel Isles. Two other species sometimes claimed for the British Isles (F. guestfalica Boenn. ex Reichb. and F. indigesta Boiss.) are excluded for various reasons given. One species (F. ovina L.) is divided into three subspecies: the diploid subsp. ovina (commonest in the north); and the tetraploid subsp. hirtula (Hackel ex Travis) M. Wilkinson (the commonest taxon of the aggregate in the British Isles) and subsp. ophioliticola (Kerguélen) M. Wilkinson (scattered throughout the British Isles, but commonest on chalk and limestone and not restricted to serpentine soils as once thought).  相似文献   

5.
A Y chromosome census of the British Isles   总被引:7,自引:0,他引:7  
The degree of population replacement in the British Isles associated with cultural changes has been extensively debated. Recent work has demonstrated that comparisons of genetic variation in the British Isles and on the European Continent can illuminate specific demographic processes in the history of the British Isles. For example, Wilson et al. used the similarity of Basque and Celtic Y chromosomes to argue for genetic continuity from the Upper Palaeolithic to the present in the paternal history of these populations (see also ). Differences in the Y chromosome composition of these groups also suggested genetic signatures of Norwegian influence in the Orkney Islands north of the Scottish mainland, an important center of Viking activities between 800 and 1300 A.D. More recently, Weale et al. argued for substantial Anglo-Saxon male migration into central England based on the analysis of eight British sample sets collected on an east-west transect across England and Wales. To provide a more complete assessment of the paternal genetic history of the British Isles, we have compared the Y chromosome composition of multiple geographically distant British sample sets with collections from Norway (two sites), Denmark, and Germany and with collections from central Ireland, representing, respectively, the putative invading and the indigenous populations. By analyzing 1772 Y chromosomes from 25 predominantly small urban locations, we found that different parts of the British Isles have sharply different paternal histories; the degree of population replacement and genetic continuity shows systematic variation across the sampled areas.  相似文献   

6.
The vertical distribution of benthic marine algae on a sublittoral cliff in the Isles of Scilly is described and briefly compared with that found in other parts of the British Isles.  相似文献   

7.
SEAWARD, M. R. D., 1987. Progress in the study of the lichen flora of the British Isles. Advances in our taxonomic, ecological and geographical knowledge of the lichen flora of the British Isles over the past three centuries are assessed. The growth of literature and the development of field recording are critically surveyed, complemented by numerical and cartographical analyses. The evolution of a comprehensive programme of network recording is described and evaluated. The present and future use of technological advances, particularly in respect of computer databases, is examined.  相似文献   

8.
West Nile virus (WNV) transmitted by mosquitoes (Diptera: Culicidae) infects various vertebrates, being pathogenic for birds, horses and humans. After its discovery in tropical Africa, sporadic outbreaks of WNV occurred during recent decades in Eurasia, but not the British Isles. WNV reached New York in 1999 and spread to California by 2003, causing widespread outbreaks of West Nile encephalitis across North America, transmitted by many species of mosquitoes, mainly Culex spp. The periodic reappearance of WNV in parts of continental Europe (from southern France to Romania) gives rise to concern over the possibility of WNV invading the British Isles. The British Isles have about 30 endemic mosquito species, several with seasonal abundance and other eco-behavioural characteristics predisposing them to serve as potential WNV bridge vectors from birds to humans. These include: the predominantly ornithophilic Culex pipiens L. and its anthropophilic biotype molestus Forskal; tree-hole adapted Anopheles plumbeus Stephens; saltmarsh-adapted Ochlerotatus caspius Pallas, Oc. detritus Haliday and Oc. dorsalis (Meigen); Coquillettidia richiardii Ficalbi, Culiseta annulata Schrank and Cs. morsitans (Theobald) from vegetated freshwater pools; Aedes cinereus Meigen, Oc. cantans Meigen and Oc. punctor Kirby from seasonal woodland pools. Those underlined have been found carrying WNV in other countries (12 species), including the rarer British species Aedes vexans (Meigen), Culex europaeus Ramos et al., Cx. modestus Ficalbi and Oc. sticticus (Meigen) as well as the Anopheles maculipennis Meigen complex (mainly An. atroparvus van Thiel and An. messeae Falleroni in Britain). Those implicated as key vectors of WNV in Europe are printed bold (four species). So far there is no proof of any arbovirus transmission by mosquitoes in the British Isles, although antibodies to Sindbis, Tahyna, Usutu and West Nile viruses have been detected in British birds. Neighbouring European countries have enzootic WNV and human infections transmitted by mosquito species that are present in the British Isles. However, except for localized urban infestations of Cx. pipiens biotype molestus that can be readily eliminated, there appear to be few situations in the British Isles where humans and livestock are exposed to sustained risks of exposure to potential WNV vectors. Monitoring of mosquitoes and arbovirus surveillance are required to guard the British Isles against WNV outbreaks and introduction of more anthropophilic mosquitoes such as Stegomyia albopicta (Skuse) and Ochlerotatus japonicus (Theobald) that have recently invaded Europe, since they transmit arboviruses elsewhere.  相似文献   

9.
The scarcer freshwater fishes of the British Isles   总被引:1,自引:0,他引:1  
This, the first of two papers on the scarcer freshwater fishes of the British Isles, gives an account of the introduced species. Nineteen species are included. The natural distribution of these fishes, the history of their introduction, their success in acclimatization, and their present distribution in the British Isles are given. A brief discussion on the introduction of exotic fishes to aquatic ecosystems follows.  相似文献   

10.
Abstract One hundred and sixty-four strains of myxobacteria were isolated from soil collected in the British Isles and tested for their antimicrobial activity. The organisms were indentified as belonging to the genera Corallococcus, Cystobacter and Myxococcus with smaller numbers of Archangium, Sorangium and Stigmatella . The majority of the isolates showed antimicrobial activity when overlaid with agar inoculated with test organisms and 77% inhibited Micrococcus luteus and 23% Botrytis cinerea . The activity was shown to be due to antibiotics excreted into the medium and soluble in chloroform. The results are discussed in relation to the importance of myxobacteria in soil ecology.  相似文献   

11.
The species ofDermatocarponoccurring in the British Isles are reviewed, with special reference to the hydrophilous species; a number of related species not yet recorded for the British Isles are also briefly treated.Dermatocarpon deminuensandD. leptophyllodesare confirmed as British; the nameD. leptophyllumshould be deleted from the British list. The nameD. meiophyllumis shown to be based on discordant elements. A key is provided to the British and Irish species.  相似文献   

12.
With reference to the author's compilation of British rotifer records, the main contributions to our knowledge of rotifers in the British Isles are outlined and the impetus provided by local natural history societies is commented upon. The usefulness and limitations of early records are examined and the scope offered to future collectors is discussed.  相似文献   

13.
The barbel was originally a fish with a relatively restricted range in the British Isles. However, despite the general environmental degradation of many British rivers, and in contrast with some native freshwater fishes, the barbel is now more widely distributed than it was a century ago. It may even be more abundant numerically.  相似文献   

14.
15.
Mycobacterium bovis is the cause of tuberculosis in cattle and is a member of the Mycobacterium tuberculosis complex. In contrast to many other pathogenic bacterial species, there is little evidence for the transfer and recombination of genes between cells. The clonality of this group of organisms indicates that the population structure is dominated by reductions in diversity, caused either by population bottlenecks or selective sweeps as entire chromosomes become fixed in the population. We describe how these forces have shaped not only the phylogeny of this group but also, at a very local level, the population structure of Mycobacterium bovis in the British Isles. We also discuss the practical implications of applying this knowledge to understanding the spread of infection and the development of improved vaccines and diagnostic tests.  相似文献   

16.
The geographical distribution of the red alga Pterosiphonia complanata (Clem.) Falkenb. is described. New records confirm that it is restricted to the warmer waters of the North Atlantic and extend its known distribution in the British Isles where it is at the northern limits of its range. The apparent scarcity and restricted distribution of the species in the British Isles and the absence of sexual plants throughout its range are discussed in relation to the habitat and possible life history of the species.  相似文献   

17.
Summary

The pteridophyte flora of Scotland, as with that of the British Isles as a whole, is still recovering from the great reduction of its original diversity caused by the Pleistocene glaciations. However, the isolation of the British Isles, their range of suitable habitats and their climatic and edaphic opportunity has provided conditions in which processes of natural biodiversity restoration in pteridophytes can be demonstrated and monitored. The modern pteridophyte vegetation of Scotland is analyzed in this evolutionary perspective. Using the examples of both ferns and fern allies, it is suggested that it is at least as important to conserve suitable sites for the continued origin of novel taxa as it is to allow for the perpetuation of existing taxa and communities.  相似文献   

18.
Data on geographical variation in allele frequencies at enzyme coding loci in Atlantic salmon from the British Isles were collated from published and unpublished sources. Statistically significant differences in allele frequencies were found among samples both within and among river systems, suggesting that the Atlantic salmon in the British Isles is not a panmictic population and that even within major river systems it cannot be treated as a single genetic stock for fisheries management purposes. Although there was some evidence of regional differences in the frequency of some rare alleles, most single‐locus variation did not show strong geographic patterns, with the exception of the AAT‐4 * locus at which allele frequencies had a significant latitudinal cline. There was some evidence for the existence of genetically‐distinct celtic and boreal races of Atlantic salmon in the British Isles as previously has been suggested. Multiple regression analyses revealed associations between genetic variation and local environmental conditions ( i.e . between variation at MEP‐2 * and both temperature and local river gradient), providing additional evidence for adaptive population divergence in the species.  相似文献   

19.
The genetic relationships of populations of the diving beetle Hydroporus glabriusculus in the British Isles and Sweden were examined using allozyme electrophoresis. H. glabriusculus is widespread in the far north of Eurasia, and occurs further south in western and central Europe as isolated relict colonies in fens whose development dates back to the early Postglacial. Study of genetic distance data reveals that the relict colonies of this insect in the British Isles do not form a distinct phylogeographic lineage, but instead belong to a number of separate groups, one of which also occurs in Sweden. Beetles from Ireland, Scotland and Norfolk appear to have diverged from each other during the Pleistocene, and colonized the British Isles in the early Postglacial in separate waves. Populations in the Norfolk Breck are closely related to the Swedish population studied, these two groups apparently having diverged during the Windermere Interstadial. All Norfolk colonies show remarkably similar depauperate levels of genetic variability, which is considered to have resulted from bottlenecking of an ancestral populaton in the Late Glacial. This study demonstrates that the recent historical biogeography of the biota of north-west Europe may be more complex than would appear from a simple consideraton of Holocene events.  相似文献   

20.
A survey of the parasites of 243 fish belonging to 13 species, from the Corrib catchment area, western Ireland, was undertaken. At least 32 species of metazoan parasites were shown to be present. Diplostomum gasterostei, Tylodelphys clavata, Eubothrium salvelini, Cucullanus truttae, Raphidascaris acus, Ergasilus gibbus and Salmincola gordoni appear to be first records for Ireland and Phyllodistomum conostomum has not previously been reported from the British Isles. New host records involving Lamptera planeri, Salvelinus alpinus, Abramis brama, Noemacheilus barbatulus, Anguilla anguilla and Pungitius pungitius for the British Isles are given.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号