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1.
A pleasing consequence of Norway rat eradication: two shrew species recover   总被引:1,自引:0,他引:1  
Four to 10 years after the successful eradication of the Norway rat (Rattus norvegicus) from three islands of the Sept–Îles Archipelago and one in the Molène Archipelago (Brittany, France), the abundance index of the lesser white‐toothed shrew (Crocidura suaveolens) increased by factors of 7–25, depending on the island and the year. Moreover, in the same region, the abundance index of the greater white‐toothed shrew (Crocidura russula) on Tomé Island increased by factors of 9 and 17, one and two years after the Norway rat eradication, respectively. The maximum variation of the abundance index for the lesser white‐toothed shrew during seven years on the rat‐free island of Béniguet in the same region was a factor of only 2.5. Moreover, the distribution of the lesser white‐toothed shrew on Bono island, restricted before the eradication to two steep areas with few rats, increased and encompassed virtually the entire island four years after rats disappeared. These results suggest strong detrimental interactions between the introduced Norway rat and the two Crocidura shrew species on temperate oceanic islands. However, our data do not indicate the ecological mechanisms at work in these interactions. The main reason this shrew recovery was detected after rat eradication was the inclusion in the eradication protocol of the evaluation of impacts on the local biota of eliminating alien species. The rigor of the sampling procedure was also crucial to this discovery. This example demonstrates that an eradication operation can be extremely useful for both scientists and managers if it is planned as a research project.  相似文献   

2.
Despite the important role of shrews (Soricomorpha: Soricidae) in the functioning of ecosystems, as predators and prey, the effects of habitat loss and fragmentation on this guild of mammals are still unclear. We studied the distribution of 5 species (the greater white toothed shrew Crocidura leucodon; the lesser white toothed shrew Crocidura suaveolens; the pigmy shrew Sorex minutus; the Appennine shrew Sorex samniticus and the Etruscan shrew Suncus etruscus) in a fragmented landscape in central Italy.Shrews were trapped with pitfall traps made from plastic water bottles, the number of traps increased with patch size. A total of 170 individuals, of 5 species of shrews were captured. Shrews were widely distributed in our study area, however patch occupancy was determined mainly by vegetation and geometrical characteristics of the patches. Our data supports the hypotheses that patterns of habitat selection and the dynamics of seasonal abundance (habitat and temporal partitioning between similarly sized species) reduce competitive pressure, thus allowing coexistence of shrews in relatively species-rich assemblages, for such small amounts of habitat. The most important outcome of our results is the crucial role played by vegetation structure in determining distribution patterns. These results strongly suggest that measurements of the vegetation structure of habitat patches should always be included as explanatory variables when studying the distribution of shrews in fragmented landscapes.  相似文献   

3.
Molecular phylogeny of crocidurine shrews (Insectivora, Soricidae) in northeastern Asia was investigated to confirm the taxonomic status of unidentified specimens ofCrocidura from Cheju Island, South Korea. Phylogenetic trees were constructed by neighbor-joining (NJ) and maximum likelihood (ML) methods, based on mitochondrial cytochromeb gene sequences (402 base pairs) of 37 individuals of seven crocidurine species and three unidentified specimens from 31 localities mainly in northeastern Asia. Phylogenetic position of the three unidentified specimens from Cheju Island were compared with those of Suncus murinus,C. attenuata, C. dsinezumi, C. lasiura, C. sibirica, C. suaveolens, andC. watasei. Both in NJ and ML trees, the three unidentified specimens were included in the cluster ofC. dsinezumi and were obviously different fromC. suaveolens on Cheju Island. Thus, the present investigation demonstrated that bothC. suaveolens andC. dsinezumi exist on Cheju Island.  相似文献   

4.
The aim of our study was to compare the shrew community diversity and structure in gradients of tropical forest degradation and restoration. Four plots within each of six habitats of the Ziama Biosphere Reserve were surveyed, including primary forest, secondary forest, cultivated fields, recently (less than 3 years) abandoned fields, young (10–12 years) forest restoration plots, and old (34 years) restoration plots. From August to November 2003, we pitfall-trapped 2,509 shrews representing 11 species. Shrew species richness and composition was similar in the six habitat surveyed, while shrew species abundance varied between habitats. Canopy height and cover, density of stems and trees and understorey density were shown to constitute important parameters influencing the abundance of several shrew species. After clear-cutting, restoration of key attributes of the forest vegetation structure was possible in 10–34 years, either by natural regeneration or by planting of seedlings. The relative abundance of most shrew species was similar between restoring forest (i.e., young restoration plots or fallows) and primary forest. Considering the advantages and disadvantages of these two methods of forest restoration, one of the most suitable management practices to restore forest while preserving shrew biodiversity could be to perform an alternation of native seedling plantation lines and fallows.  相似文献   

5.
Competition for resources has long been considered a major driver of evolution by natural selection. Thus, the ability to gain access to resources not available to other individuals and species should be under strong selection. In the present study, we focus on the potential role of biting in a shrew (Crocidura russula) because this trait may confer two advantages: (1) a broadening of the dietary niche and (2) the provision of direct superiority in interspecific interactions. The model chosen is the greater white‐toothed shrew, which is considered as invasive in northern Europe and which is also known to displace native species of shrew in this area. Moreover, its distribution appears to constrain the distributional ranges of other species of shrew in the Maghreb. We use geometric morphometrics and a simple biomechanical model to describe shape variation and to evaluate the mechanical potential of the mandible of ten species of white‐toothed shrews, with a special emphasis on C. russula and Crocidura suaveolens. We find that C. russula possesses an intermediate mechanical potential linked with an intermediate level of shape variability. Our results suggest that the higher mechanical potential may explain the observed pattern of colonization of the Atlantic islands by C. russula at the expense of C. suaveolens. Finally, our results also suggest that the ability to bite hard may be under strong selection in shrews. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 795–807.  相似文献   

6.
Cyclic population dynamics of small mammals are not restricted to the boreal and arctic zones of Eurasia and North America, but long-term data series from lower latitudes are still less common. We demonstrated here the presence of periodic oscillations in small mammal populations in eastern Poland using 22-year (1986–2007) trapping data from marginal meadow and river valley grasslands located in the extensive temperate woodland of Białowieża Primeval Forest. The two most common species inhabiting meadows and river valleys, root vole Microtus oeconomus and common shrew Sorex araneus, exhibited synchronous periodic changes, characterised by a 3-year time lag as indicated by an autocorrelation function. Moreover, the cycles of these two species were synchronous within both habitats. Population dynamics of the striped field mouse Apodemus agrarius was not cyclic. However, this species regularly reached maximum density 1 year before the synchronized peak of root voles and common shrews, which may suggest the existence of interspecific competition. Dynamics of all three species was dominated by direct density-dependent process, whereas delayed density dependent feedback was significant only in the root vole and common shrew. Climatic factors acting in winter and spring (affecting mainly survival and initial reproduction rates) were more important than those acting in summer and autumn and affected significantly only the common shrew. High temperatures in winter and spring had positive effects on autumn-to-autumn changes in abundance of this species, whereas deep snow in combination with high rainfall in spring negatively affected population increase rates in common shrew.  相似文献   

7.
Populations of the “continental” Great Cormorant P. c. sinensis have expanded from north-eastern Europe towards the western part of the range of the “marine” P. c. carbo breeding in the United Kingdom and France. The aim of the study was to test the hypothesis of ecological segregation between subspecies by analysing the structuring of the European populations. Sequencing the mtDNA of 231 birds belonging to 20 colonies revealed 38 haplotypes based on 25 polymorphic sites (5.76% sequence divergence). P. c. sinensis (“S”) was well confirmed, but usual P. c. carbo formed two coastal populations, the real P. c. carbo “C” mainly in the western part of the range (United Kingdom, coastal France), and also in Norway and Sardinia, and “N”, branched to the Japanese Cormorant P. capillatus and probably isolated by glaciations, mainly present in the Nordic range (Norway, but also on the coasts from Sweden to Brittany), we named P. c. norvegicus. In a variable position in the trees but close to C is a group of undetermined origin haplotypes, named U, also present in both traditional ranges. The new tree-nesting colonies in Brittany are clearly a mixture of S and the two clades C and N previously described as P. c. carbo, with a decreasing proportion of C + N between 1993 (67%), 1996 (60%) and 2002 (33%) for the pioneering Grand-Lieu colony. These results confirmed the current introgression of continental populations in the western range, with probable hybridization. Although the subspecies can switch habitats locally due to social behaviour and migrations, the ecological segregation between the two usual subspecies appears to be largely confirmed in Europe.  相似文献   

8.
The deep-benthic chondrichthyan fishes collected by 584 hauls of otter-trawl from the Okinawa Trough, Kyushu-Palau Ridge, Pacific continental slope off northern Honshu Island (“Tohoku Slope”) and continental slope of Okhotsk Sea off Hokkaido (“Okhotsk Slope”) were analyzed. Sixty-one species were recorded from 200 to 1,520 m in depths; 37 species from the Okinawa Trough, 10 from the Kyushu-Palau Ridge, 18 from the Tohoku Slope, and nine from the Okhotsk Slope. The Okinawa Trough has the most varied composition, with many species of the Squalidae, Scyliorhinidae, and Rajidae (genusRaja). The Kyushu-Palau Ridge has a relatively high number of squalid species, but no species of the Rajidae or Chimaeriformes. The Tohoku Slope fauna is relatively varied, comprising six families, of which the Rajidae (genusBathyraja) is the most numerous, followed by the Squalidae. The Okhotsk Slope has the least number of species, and is characterized by a remarkable dominance of the Rajidae (genusBathyraja).  相似文献   

9.
We developed eight polymorphic microsatellite loci to study the natural populations of Crocidura suaveolens, the lesser white‐toothed shrew. These loci are used in the study of insular populations of the French Atlantic coast where these shrews exhibit gigantism features that suggest an insular syndrome. These populations were threatened by the invasion of the rat Rattus norvegicus and the eradication of this alien pest in some islands was followed by a demographic expansion of the shrew populations. These first genetic results suggest that the shrew populations in the three studied islands are very differentiated.  相似文献   

10.
Classic ecological restoration seems tacitly to have taken the Clementsian “balance of nature” paradigm for granted: plant succession terminates in a climax community which remains at equilibrium until exogenously disturbed after which the process of succession is restarted until the climax is reached. Human disturbance is regarded as unnatural and to have commenced in the Western Hemisphere at the time of European incursion. Classic ecological restoration thus has a clear and unambiguous target and may be conceived as aiming to foreshorten the natural processes that would eventually lead to the climax of a given site, which may be determined by its state at “settlement”. According to the new “flux of nature” paradigm in ecology a given site has notelos and is constantly changing. Human disturbance is ubiquitous and long-standing, and at certain spatial and temporal scales is “incorporated”. Any moment in the past 10,000 years that may be selected as a benchmark for restoration efforts thus appears to be arbitrary. Two prominent conservationists have therefore suggested that the ecological conditions in North America at the Pleistocene—Holocene boundary, prior to the anthropogenic extinction of the Pleistocene megafauna, be the target for ecological restoration. That suggestion explicitly assumes evolutionary temporal scales and continental spatial scales as the appropriate frame of reference for ecological restoration. However, ecological restoration should be framed in ecological spatio-temporal scales, which may be defined temporally in reference to ecological processes such as disturbance regimes and spatially in reference to ecological units such as landscapes, ecosystems, and biological provinces. Ecological spatio-temporal scales are also useful in achieving a scientifically defensible distinction between native and exotic species, which plays so central a role in the practice of ecological restoration and the conservation of biodiversity. Because post-settlement human disturbances have exceeded the limits of such scales, settlement conditions can be justified scientifically as appropriate targets of restoration efforts without recourse to obsolete teleological concepts of equilibria and without ignoring the presence and ecological influence of indigenous peoples.  相似文献   

11.
Trois Baculovirus isolés de larves deSpodoptera littoralis atteintes de polyédroses nucléaires au Maroc, en Egypte et dans un élevage à Lyon ont été comparés par analyse de leurs génomes avec des enzymes de restriction. Les variants génétiques contenus dans les populations virales sont obtenus après isolement de clones en culture cellulaire. Sur 27 clones analysés par les endonucléases on observe 11 variants avecEco RI, 3 variants avecBam HI et avecSac I et un type unique avecHin dIII. Les 3 virus Maroc, Egypte et Lyon sont différents, mais appartiennent à l'espèce B définie parCherry & Summers (1985). Summary Three Baculoviruses were isolated fromSpodoptera littoralis larvae infected with nuclear polyhedrosis (NPV) collected from Morocco, Egypt, and a from laboratory culture at Lyon (France). Their genomes were compared by restriction endonuclease analysis. The genotypic variants contained in the viral populations were obtained after isolation of clones in cell culture. Among the 27 clones analyzed by restriction endonucleases, 11 variants were observed withEco RI, 3 variants withBam HI andSac I, and one unique type withHin dIII. These 3 viruses “Morocco”, “Egypt”, and “Lyon” are different, but belong to type B ofS. littoralis NPV as defined byCherry & Summers (1985).

avec la collaboration technique de BéatriceChebli.  相似文献   

12.
The terrestrial small mammal community of the Zakouma National Park (Chad) was assessed by live trapping in various habitats during the dry season. Nearly 3000 trap-nights yielded 505 captures of nine rodent and two shrew species, making up a representative small mammal community for the Sudanian savanna biotic zone. Murine rodents of the genusMastomys dominated, withM. erythroleucus andM. cf.kollmannspergeri occuring at similar abundances. The former was widespread and especially abundant in habitats with high tree cover. The latter was more localized, predominantly in annually flooded habitats characterized by a clay-rich soil, often withAcacia seyal as the main vegetation. Population structure differed between the two species, suggesting distinct reproductive strategies possibly linked with habitat preferences: theM. erythroleucus population comprised mainly young, immature individuals, whereasM. cf.kollmannspergeri was represented by older individuals, a significant fraction of which had already reproduced.Taterillus congicus andTatera kempi (gerbilline rodents), together withLemniscomys zebra, were mainly found in more open habitats with sand-rich soils.Arvicanthis niloticus, Acomys cf.johannis, Mus mattheyi andXerus erythropus were the other rodents captured, whereas shrews were represented byCrocidura fulvastra andSuncus sp.  相似文献   

13.
We used multidirectional chromosome painting with probes derived by bivariate fluorescence-activated flow sorting of chromosomes from human, black lemur (Eulemur macaco macaco) and tree shrew (Tupaia belangeri, order Scandentia) to better define the karyological relationship of tree shrews and primates. An assumed close relationship between tree shrews and primates also assists in the reconstruction of the ancestral primate karyotype taking the tree shrew as an ”outgroup” species. The results indicate that T. belangeri has a highly derived karyotype. Tandem fusions or fissions of chromosomal segments seem to be the predominant mechanism in the evolution of this tree shrew karyotype. The 22 human autosomal painting probes delineated 40 different segments, which is in the range found in most mammals analyzed by chromosome painting up to now. There were no reciprocal translocations that would distinguish the karyotype of the tree shrew from an assumed primitive primate karyotype. This karyotype would have included the chromosomal forms 1a, 1b, 2a, 2b, 3/21, 4–11, 12a/22a, 12b/22b, 13, 14/15, 16a, 16b, 17, 18, 19a, 19b, 20 and X and Y and had a diploid chromosome number of 2n=50. Of these forms, chromosomes 1a, 1b, 4, 8, 12a/22a, and 12b/22bmay be common derived characters that would link the tree shrew with primates. To define the exact phylogenetic relationships of the tree shrews and the genomic rearrangements that gave rise to the primates and eventually to humans further chromosome painting in Rodentia, Lagomorpha, Dermoptera and Chiroptera is needed, but many of the landmarks of genomic evolution are now known. Received: 11 February 1999; in revised form: 17 June 1999 / Accepted: 20 July 1999  相似文献   

14.
The habitat occurrence and invertebrate prey distribution of nine species of shrew in the mid-taiga of central Siberia were investigated. Species richness ranged from 4–9 shrews per habitat. Sorex araneus and S. caecutiens were numerically dominant in all seven habitats (44 and 36% of the total catch, respectively) while Sorex minutus, S. tundrensis, S. isodon , and S. roboratus each constituted 4–6% and Sorex minutissimus, S. daphaenodon , and Neomys fodiens were rare (< 1% each). There was no overall correlation between abundance of shrews and invertebrate prey, but flood-plain habitats supported the greatest abundance and species richness of shrews, and high density and biomass of prey. Oligochaete-eating shrews were twice as numerous here as in other habitats, coincident with high abundance of oligochaetes. The large, earthworm-feeding Sorex roboratus occurred only here. The more acid, typical taiga habitats had lower adundance and species richness of shrews. They had the lowest density and biomass of prey, particularly oligochaetes, and far fewer oligochaete-eating shrews. The relative paucity of shrews in bush-meadow habitats, despite abundant prey, implied that habitat structure influences shrew distribution. Differential numbers of certain species in the presence or absence of larger congeners also suggested that interspecific competitive effects influence habitat selection by shrews. The high species richness of shrews here in the mid-taiga may be accounted for by the heterogeneous nature of the constituent habitats which provide niches for small and large species of shrew with a range of feeding habits.  相似文献   

15.
R. M. Beach  J. W. Todd 《BioControl》1986,31(3):237-242
Field grown foliage from the resistant soybean [Glycine max (L.) Merrill] breeding line GAT “81–327” and the susceptible cultivar “Ransom” was used to rear unparasitized larvae of the soybean looper (SBL),Pseudoplusia includens (Walker), and larvae parasitized byCopidosoma truncatellum (Dalman). SBL larvae, whether parasitized or not, consumed more foliage when fed “Ransom”. Unparasitized larvae reared on “81–327” had longer developmental times and suffered greater mortality than unparasitized larvae reared on “Ransom”. Parasitization of SBL larvae byC. truncatellum increased total foliage consumption of both soybean lines. Parasitized larvae reared on the resistant “81–327” weighed less and yielded fewer parasitoid adults.
Résumé Des larves dePseudoplusia includens (Walker) parasitées ou non parCopidosoma truncatellum (Dalman) ont été nourries des feuilles de deux lignées de soja [Glycine max (L.) Merrill] l'une, GAT “81–327” résistante et l'autre, “Ransom” sensible. Les larves deP. includens qu'elles soient parasitées ou non consommaient plus de feuillage lorsqu'elles étaient nourries de la lignée “Ransom”. Les larves non parasitées élevées sur “81–327” avaient un cycle de développement beaucoup plus long et un taux de mortalité beaucoup plus élevé que les larves non parasitées élevées comparativement sur feuilles de “Ransom”. Par contre, les larves parasitées manifestaient une consommation accrue du feuillage des deux lignées de soja. Les larves parasitées élevées sur les feuilles de la variété résistante GAT “81–327” pesaient moins et produisaient moins également de parasites adultes.
  相似文献   

16.
Martin Fikáček 《Biologia》2006,61(2):149-157
Pachysternum loxodonta sp. n. from the Republic of the Congo and Pachysternum sulawesicum sp.n. from Sulawesi Island, Indonesia are described. The generic status of Pachysternum sculpticolle (Régimbart, 1907) is revised, the species is transferred to the genus Cyrtonion and its differences from C. ghanense Hansen, 1989 are discussed. Taxonomy of Pachysternum is discussed, dividing the genus prelusively into three species groups, one comprising all known Oriental and Eastern Palearctic species, and two comprising the Afrotropical species. Species with unclear positions within the genus Pachysternum or with questionable generic status are left as “Species incertae sedis”.  相似文献   

17.
A canonical variate analysis was used to summarize the distribution pattern of 30 species of dung beetles (Scarabaeinae) from 162 sites in the Iberian peninsula (Spain and Portugal) in relation to 4 site variables. The best separation of beetle species, obtained using a xerothermic climatic index, was into 3 groups called “mediterranean”, “unrestricted” and “temperate”. Little further separation was achieved using altitude, dung type or soil type. These data are used to select dung beetles for introduction to south-western Australia for bush fly control.
Résumé On a fait appel à l'analyse de variables canoniques pour résumer le plan de distribution, relatif à 4 variables de localité, de 30 espèces de bousiers (Scarabaeinae) de 162 localités de la Péninsule ibérique (l'Espagne et le Portugal). La meilleure division des espèces, obtenue à l'aide d'un indice xérothermique climatique, se faisait en 3 groupes désignés respectivement comme “méditerranéen”, “ubiquiste” et “tempéré”. Peu de séparation supplémentaire a été obtenue en ayant recours à des facteurs d'altitude, de nature de la bouse ou de type de sol. Ces données ont été employées pour aider à la sélection de bousiers destinés à être introduits en Australie Occidentale pour y combattreMusca vetustissima Walker[Diptera].
  相似文献   

18.
Summary.  Two glutamic acid analogs (1SR,3RS,4RS)- and (1SR,3SR,4SR)-1-amino-4-phosphono cyclopentane-1,3-dicarboxylic acids (APCPD) have been synthesized. Pure E-(diethoxy-phosphoryl)-acrylic acid ethyl ester was obtained from ethyl propiolate, phenol and triethylphosphite. It was used as dienophile in a Diels-Alder reaction. Oxidation and cyclization afforded 3-(ethoxy-carbonyl)-4-(diethoxy-phosphoryl)-cyclopentanone. Bucherer-Bergs reaction and hydrolysis yielded APCPD-III and -IV which are inactive on mGlu1a receptor and antagonists on mGlu2 and mGlu8a receptors. Received April 2, 2002 Accepted July 11, 2002 Published online December 18, 2002 Acknowledgments This work was supported by grants from the CNRS, the programs “Physique et Chimie du Vivant” (PCV00–134, CNRS) and “Molécules et Cibles Thérapeutiques” (CNRS/INSERM), RETINA France and the Fondation de France (Comité Parkinson). A.-S. B. was supported by fundings from Parke-Davis Pharmaceutical Research (Ann Arbor, MI) and the Fondation de la Recherche Médicale. Authors' address: Dr Francine C. Acher, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601-CNRS, Université René Descartes-Paris V, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France, Fax: (33) 1 42 86 83 87, E-mail: acher@biomedicale.univ-paris5.fr  相似文献   

19.
The feeding ecology of a multi-species community of shrews inhabiting secondary forest and cacao-coffee plantations in the Tai National Park (Ivory Coast) was investigated. A total of 553 shrews were captured and 194 alimentary tracts were examined. Ten species were found, includingSylvisorex megalura and nine species ofCrocidura, forming a series with respect to body size. New ecological data on these little known African species are presented. All species of shrews ate a wide diversity of arthropods, with Coleoptera, Araneae, Formicidae and Diplopoda making the largest dietary contributions. Lumbricidae were eaten by two species.C. obscurior had an exceptionally long intestine for its size but there was no evidence of dietary specialisation in this or other shrew species. All species investigated ate predominantly small prey and there was no correlation between size of prey items consumed and body mass of shrew species. There was little evidence of resource partitioning amongst the shrews, despite differences in body size.  相似文献   

20.
Peter VOGEL 《Mammal Review》2012,42(4):314-318
The presence of the Etruscan shrew Suncus etruscus is hard to prove where its predator, the barn owl Tyto alba, is absent, because most live traps are not triggered by it. I therefore developed a new trapping method involving a feeding period of 1 week followed by one night of trapping using modified Trip Trap traps. I show here in detail how I caught four Etruscan shrews in 2010 with 24 traps in the Valley of Dora Baltea (Piemonte, Italy). In 2011, another 11 Etruscan shrews were caught in Piemonte and Lombardia, Italy, and Ticino, Switzerland. The proposed new method is useful for establishing the presence of the species.  相似文献   

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