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1.
Introduced species often become ecologically dominant, displacing native species and posing a serious threat to ecosystem function and global biodiversity. Ants are among the most widespread and damaging alien species; introductions are often accompanied by population-level behavioural and genetic changes contributing to their success. We investigated the genetic structure, chemical profile and nestmate recognition in introduced populations of the invasive big-headed ant, Pheidole megacephala, in Australia. Behavioural analyses show that workers are not aggressive towards conspecifics from different nests, even at large geographical scales (up to 3000 km) and between populations encompassing a wide range of environmental conditions. By contrast, interactions with workers of other species invariably result in agonistic behaviours. Genetic analyses reveal that populations have low genetic diversity. No genetic differentiation occurs among nests of the same population; differentiation between populations, though significant, remains weak. Chemical analyses indicate that cuticular lipids are similar between colonies of a population, and that differentiation between populations is low. Altogether, these results indicate that the big-headed ant P. megacephala forms a large unicolonial population across northern/eastern Australia. 相似文献
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ROLAND ALLEMAND FRANCOIS POMPANON FREDERIC FLEURY PIERRE FOUILLET MICHEL BOULETREAU 《Physiological Entomology》1994,19(1):1-8
Abstract. A video analysis system was developed to study behavioural circadian rhythms in insects. Technical innovations were performed in image analysis and in the use of robotics. In image analysis, both the automatic detection of the insect and the calculation of several variables (linear and angular speed, locomotor activity, etc.) are carried out in real-time, which saves time and allows long-term studies without any intervention of the operator. The displacement of the camera by robotics allows the simultaneous study of many individuals (i.e. sixty individuals for the study of locomotor activity of adult insects, more than 400 individuals for the study of the emergence of adult parasitoids from their host). Four applications of this new device are presented. They deal with circadian rhythms in parasitoid insects: locomotor activity and time variation in locomotory parameters, daily distribution of the emergence and onset of the locomotor activity in adults. The adaptability of the system to several experimental materials and situations is discussed and the interest of the study of behavioural rhythms in the approach of host-parasitoid associations is emphasized. 相似文献
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KEIKO KITAMURA KOSUKE HOMMA† HIDEKI TAKASU‡ SHINSUKE HAGIWARA§ FREDERICK H. UTECH¶ DENIS F. WHIGHAM†† SHOICHI KAWANO 《Plant Species Biology》2001,16(3):219-230
Populations of American beech in Virginia and the Great Smoky Mountain National Park in Tennessee and North Carolina were investigated for demographic genetic substructurings. Two Virginia populations, one on the Blue Ridge (WG1) and the other on the Piedmont (WG2) occur over an elevational gradient of several hundreds meters. One of the Great Smoky Mountain populations (GS1) was in a 'beech gap' and the other (GS2) in a 'cove forest' along a creek. The populations in the Great Smoky Mountain National Park were only separated by a few hundred meters in elevation, but both on the same physiographic province. The populations had two growth forms. Trees produced extensive root suckers at WG1, GS1 and GS2, but WG2 had no root suckers and all individuals had obviously been established from seeds. A total of 1335 shoots were mapped at the four sites, their size measured [diameter at breast height (DBH) or diameter at ground height (DGH)], and genotypes were determined for each locus using allozyme analysis. FIS among five different size-classes revealed an excess of homozygotes in WG1, GS1 and GS2, and an excess of heterozygotes in WG2. The offshoot formation from root suckers obviously contributed to the abundance of intermediate size-classes in WG1, GS1 and GS2. Exceedingly localized patchiness of different multilocus genotypes reveals genetic clustering of shoots that have obviously originated from root suckers in WG1, GS1 and GS2. The Piedmont population (WG2), on the other hand, showed loose localization of genetically related trees at a scale of 35–40 m in area, suggesting broader ranges of pollen and seed dispersal. The data are discussed in the light of the differences in growth form and mode of reproduction, and also in relation to the post-glacial migration and the current geographic distribution of the species. 相似文献
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FRÉDÉRIC JIGUET RICHARD D. GREGORY VINCENT DEVICTOR RHYS E. GREEN PETR VOŘÍŠEK ARCO VAN STRIEN DENIS COUVET 《Global Change Biology》2010,16(2):497-505
Temperate species are projected to experience the greatest temperature increases across a range of modelled climate change scenarios, and climate warming has been linked to geographical range and population changes of individual species at such latitudes. However, beyond the multiple modelling approaches, we lack empirical evidence of contemporary climate change impacts on populations in broad taxonomic groups and at continental scales. Identifying reliable predictors of species resilience or susceptibility to climate warming is of critical importance in assessing potential risks to species, ecosystems and ecosystem services. Here we analysed long‐term trends of 110 common breeding birds across Europe (20 countries), to identify climate niche characteristics, adjusted to other environmental and life history traits, that predict large‐scale population changes accounting for phylogenetic relatedness among species. Beyond the now well‐documented decline of farmland specialists, we found that species with the lowest thermal maxima (as the mean spring and summer temperature of the hottest part of the breeding distribution in Europe) showed the sharpest declines between 1980 and 2005. Thermal maximum predicted the recent trends independently of other potential predictors. This study emphasizes the need to account for both land‐use and climate changes to assess the fate of species. Moreover, we highlight that thermal maximum appears as a reliable and simple predictor of the long‐term trends of such endothermic species facing climate change. 相似文献
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Oxamyl (2.5 μg cm-3sand) applied to the roots of cucumber seedlings significantly reduced the number of vermiform second stage juveniles of Meloidogyne incognita which developed into swollen forms for at least 30 days. However, when cucumber seedlings containing nematodes were removed from oxamyl-treated sand 10 days after the pesticide was applied and placed in clean sand a large proportion of the juveniles had become swollen after a further 18 days. This suggested the effect of oxamyl on nematode development was reversible. A single foliar application of oxamyl (25–100 μg) in distilled water was also found to significantly reduce development of second stage juveniles to saccate forms However, the use of various adjuvants with a threshold foliar treatment (25 μg oxamyl) failed to significantly improve its activity. 相似文献
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JÉRÔME ORIVEL JULIEN GRANGIER JULIEN FOUCAUD JULIEN LE BRETON FRANÇOIS‐XAVIER ANDRÈS HERVÉ JOURDAN JACQUES H. C. DELABIE DENIS FOURNIER PHILIPPE CERDAN BENOIT FACON ARNAUD ESTOUP ALAIN DEJEAN 《Ecological Entomology》2009,34(4):504-512
Abstract 1. The biology of most invasive species in their native geographical areas remains largely unknown. Such studies are, however, crucial in shedding light on the ecological and evolutionary processes underlying biological invasions. 2. The present study focuses on the little fire ant Wasmannia auropunctata, a species native to Central and South America that has been widely introduced and which has become invasive throughout the tropics. We characterise and compare several ecological traits of native populations in French Guiana with those in one of its introduced ranges, New Caledonia. 3. We found ecologically heterogeneous populations of W. auropunctata coexisting in the species’ native geographical area. First, we found populations restricted to naturally perturbed areas (particularly floodplains) within the primary forest, and absent from the surrounding forest areas. These populations were characterised by low nest and worker densities. Second, we found dominant populations in recent anthropogenic areas (e.g. secondary forest or forest edge along road) characterised by high nest and worker densities, and associated with low ant species richness. The local dominance of W. auropunctata in such areas can be due to the displacement of other species (cause) or the filling‐up of empty habitats unsuitable to other ants (effect). With respect to their demographic features and ant species richness, the populations of native anthropogenic habitats were to a large extent similar to the invasive populations introduced into remote areas. 4. The results point to the need for greater research efforts to better understand the ecological and demographic features of invasive species within their native ranges. 相似文献
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DENIS J. CARR S. G. M. CARR† B. P. M. HYLAND PETER G. WILSON PAULINE Y. LADIGES 《Botanical journal of the Linnean Society. Linnean Society of London》2002,139(4):415-421
A new genus and species in the eucalypt group of the Myrtaceae is described. Stockwellia quadrifida D.J. Carr, S.G.M. Carr & B.Hyland gen. et sp. nov. is a rainforest tree of restricted distribution on the Atherton Tableland, North Queensland, Australia. Molecular data suggest that it is the sister taxon to Eucalyptopsis and this is supported by morphological characters. The prolonged hypanthium and reduced perianth appear to be synapomorphies for these two genera and the circumscissile hypanthium a synapomorphy shared with Allosyncarpia . Stockwellia differs from Eucalyptopsis by the distinct, albeit reduced, perianth and the hypanthium splitting into four segments at anthesis. The relationship of these two genera indicates an historical biogeographical link between New Guinea and the Queensland wet tropics region. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 415–421. 相似文献