关键词： Composite sequences   Computer simulations   Congruence   DNA sequences   Missing data   Phylogenetic accuracy   Phylogenomics   Supermatrices  

摘要： Supermatrices are often characterized by a large amount of missing data. One possible approach to minimize such missing data is to create composite taxa. These taxa are formed by sampling sequences from different species in order to obtain a composite sequence that includes a maximum number of genes. Although this approach is increasingly used, its accuracy has rarely been tested and some authors prefer to analyze incomplete supermatrices by coding unavailable sequences as missing. To further validate the composite taxon approach, it was applied to complete mitochondrial matrices of 102 mammal species representing 93 families with varying amount of missing data. On average, missing data and composite matrices showed similar congruence to model trees obtained from the complete sequence matrix. As expected, the level of congruence to model trees decreased as missing data increased, with both approaches. We conclude that the composite taxon approach is worth considering in a phylogenomic context since it performs well and reduces computing time when compared to missing data matrices. (C) 2010 Elsevier Inc. All rights reserved.

关键词： 党支部   创先争优活动   堡垒   动物卫生监督   先锋   四川省  

摘要： 四川省动物卫生监督所党支部对党中央和四川省委在基层组织和党员深入开展创先争优活动高度重视,按照省局党组对活动的安排部署,精心谋划、科学部署,以"筑坚强堡垒、树先锋形象、促科学发展、推动事业发展"为主线,紧紧把握重大动物疫病防控和畜产品质

关键词： ARBOREAL animals   TREE cavities   MAMMALS -- Habitat   OPOSSUMS   DEAD trees   DASYURIDAE  

摘要： Many species of non-flying mammal depend on tree hollows (cavities or holes) for shelter and survival. I reviewed the published literature on tree hollow use by Australian non-flying arboreal and scansorial mammals to provide a synthesis of tree hollow requirements, to identify gaps in knowledge and to stimulate future research that may improve the management of these species. The use of hollows was described in some detail for 18 of 42 hollow-using species. Most information was for possums and gliding possums, whereas dasyurid marsupials and rodents were largely neglected. The paucity of data for many species must be addressed because it represents an impediment to their conservation. Hollow abundance appears to be the primary determinant of tree preferences. This accounts for the frequent use of standing dead trees by most species. Most hollow-bearing trees used as dens were at least 100 years of age. Further studies that describe the dynamic processes that govern the availability of tree hollows are needed. The few studies that document attrition of hollow-bearing trees suggest that land managers need to improve strategies for the effective retention and long-term replacement of these trees.

关键词： protozoan parasites   phylogenomics   universal orthologs  

摘要： We have developed a semi-automatic methodology to reconstruct the phylogenetic species tree in Protozoa, integrating different phylogenetic algorithms and programs, and demonstrating the utility of a supermatrix approach to construct phylogenomics-based trees using 31 universal orthologs (UO). The species tree obtained was formed by three major clades that were related to three groups of data: i) Species containing at least 80% of UO (25/31) in the concatenated multiple alignment or supermatrix, this clade was called C1, ii) Species containing between 50%-79% (15-24/31) of UO called C2, and iii) Species containing less than 50% (1-14/31) of UO called C3. C1 was composed by only protozoan species, C2 was composed by species related to Protozoa, and C3 was composed by some species of C1 (Protozoa) and C2 (related to Protozoa). Our phylogenomics-based methodology using a supermatrix approach proved to be reliable with protozoan genome data and using at least 25 UO, suggesting that (a) the more UO used the better, (b) using the entire UO sequence or just a conserved block of it for the supermatrix produced similar phylogenomic trees.

关键词： Agrilus planipennis Fairmaire   Coarse woody debris   Dead wood   Ecological impacts   Epigeic   Saproxylic  

摘要： Because leaf litter occurs at the interface between the soil and atmosphere, the invertebrates inhabiting it represent important linkages between above- and below-ground food webs. The responses of these organisms to forest disturbance brought about by invasive species should therefore have far-reaching ecological effects. The purpose of this study was to explore how canopy gap formation (gap fraction 1-10%) and fallen ash trees ("logs") resulting from extensive (>99%) ash tree mortality caused by the invasive emerald ash borer (EAB) affect the distributions of litter-dwelling arthropods and earthworms. These organisms did not vary in abundance across the gap fraction range studied but, as predicted from the literature, many taxa (e.g., Aranea, Coleoptera, Collembola, Diplopoda, Isopoda, Opiliones and exotic earthworms) were more abundant next to logs than away from them. Contrary to expectations, arthropods did not become more concentrated next to logs as canopy openness increased, with isopods exhibiting the opposite response. These results suggest litter-dwelling arthropods in EAB-infested forests are favored by inputs of ash wood to the forest floor but are largely unaffected by increases in canopy openness, at least across the gap fraction range studied. Published by Elsevier GmbH.

关键词： Acacia drepanolobium   ant-plant interactions   black rhino   Crematogaster   giraffe   Tetraponera  

摘要： In obligate ant-plant mutualisms, the asymmetric engagement of a single plant species with multiple ant species provides the opportunity for partners to vary in their behaviour. Variation in behaviour has implications for the interactions with third-party species such as herbivores. This study assessed the effect of obligate ant-mutualists (Crematogaster mimosae, Crematogaster nigriceps and Tetraponera penzigi) inhabiting the African ant-acacia (Acacia drepanolobium) on three mega-herbivore browsers: the Maasai giraffe (Giraffa camelopardalis tippelskirchi), the reticulated giraffe (Giraffa c. reticulata) and the black rhino (Diceros bicornis). Giraffes are abundant and wide-ranging herbivores of the acacias, whereas black rhinos are localized and perennial herbivores of the acacias. Multiyear field studies comparing the ants' aggressive behaviour and browsing by mega-herbivores suggested differences between the tending abilities of the primary ant species inhabiting A. drepanolobium. Trees occupied by the aggressive ant species C. mimosae had significantly less browsing by giraffes and black rhino than trees occupied by other ant species. The results of this study provide evidence that ant-mutualists on African acacias can serve as deterrents to mega-herbivores and that different ant species vary in their tending ***

关键词： Arthropod diversity   Community structure   ERH   Herbivory   Invasions   Trophic structure  

摘要： The success of exotic plants may be due to lower herbivore loads than those on native plants (Enemies Release Hypothesis). Predictions of this hypothesis include lower herbivore abundances, diversity, and damage on introduced plant species compared to native ones. Greater density or diversity of predators and parasitoids on exotic versus native plants may also reduce regulation of exotic plants by herbivores. To test these predictions, we measured arthropod abundance, arthropod diversity, and foliar damage on invasive Chinese tallow tree (Triadica sebifera) and three native tree species: silver maple (Acer saccharinum), sycamore (Platanus occidentalis), and sweetgum (Liquidambar styraciflua). Arthropod samples were collected with canopy sweep nets from six 20 year old monoculture plots of each species at a southeast Texas site. A total of 2,700 individuals and 285 species of arthropods were caught. Overall, the species richness and abundance of arthropods on tallow tree were similar to the natives. But, ordination (NMS) showed community composition differed on tallow tree compared to all three native trees. It supported an arthropod community that had relatively lower herbivore abundance but relatively more predator species compared to the native species examined. Leaves were collected to determine damage. Tallow tree experienced less mining damage than native trees. The results of this study supported the Enemies Release Hypothesis predictions that tallow tree would have low herbivore loads which may contribute to its invasive success. Moreover, a shift in the arthropod community to fewer herbivores without a reduction in predators may further limit regulation of this exotic species by herbivores in its introduced range.

关键词： Foraging   Herbivory   LiDAR   Savanna   Scale   Termite  

摘要： Termite mounds form islands of fertility in savanna landscapes and create foraging hotspots for herbivores, but the magnitude and spatial extent of these influences is unknown. We mapped terrain, termite mound and woody vegetation three-dimensional (3-D) structure at 56 cm resolution across a large-scale (254 ha), long-term (34 years) herbivore exclusion experiment in the Kruger National Park, with the Carnegie Airborne Observatory (CAO). We compared vegetation 3-D structure in areas protected from herbivores with those accessible to herbivores, both on termite mounds and in the landscape matrix between termite mounds. Termite mound density was 1.1 ha(-1) across the study area and mound size did not differ between protected and accessible areas. Woody vegetation canopy cover was similar to 100% greater on protected than accessible mounds, but was only similar to 20% greater in the protected inter-mound matrix when compared to the accessible matrix. Woody canopy height class distributions differed significantly between protected and accessible areas, with the tallest vegetation (>10 m) occurring on protected termite mounds. The impacts of herbivore browsing were evident at distances of up to 20 m from termite mound centres. Spatial analysis of mound distribution revealed that the sphere of termite mound influence constitutes similar to 20% of the total landscape. Termite influences on herbivore browsing operate at scales much larger than the spatial extent of their mound building activities. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Remote sensing   Habitat requirements   Australia   Spatial scale  

摘要： Tropical savannas are an important reservoir of global biodiversity. Australia's extensive savannas, although still largely intact, are experiencing substantial declines in terrestrial biodiversity due to a variety of interrelated effects of altered fire regimes, grazing and increases in invasive species. These disturbance processes are spatially variable, combine to increase landscape to local-scale landscape heterogeneity, but rarely result in well-defined patch boundaries. We quantified the importance of this heterogeneity for native reptile and small mammal species in a tropical savanna landscape of Queensland, Australia. We used high resolution remote sensing imagery (IKONOS) to map habitat pattern at a 4 m spatial resolution and at variable extents. We found that landscapes dominated by grass or bare ground had low reptile and small mammal diversity, while landscapes with a heterogeneous mix of grass, bare ground and trees had high species diversity and relative abundance of most species. Landscape heterogeneity may increase reptile and small mammal species richness by: (i) increasing the variety and abundance of foraging resources such as seeds and invertebrates;(ii) providing cover from predators and high summer temperatures;and (iii) increasing functional connectivity and dispersal success. The importance of these resources and processes varies among individual species and at different spatial scales, reiterating the need to consider habitat requirements of multiple species in landscape management and conservation planning. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： ants   habitat structure   spiders   weeds  

摘要： Habitat complexity is an important factor structuring local faunal assemblages. Many invasive plant species alter vegetation complexity because they are both functionally and structurally different from native flora. This study investigated the effects of an invasive grass (Andropogon gayanus Kunth.), which is invading undisturbed savannas in northern Australia. Although A. gayanus is a similar lifeform to that dominant in the native understory (i.e., a C4 grass), it is structurally different and significantly alters habitat complexity. We, therefore, hypothesized that there would be a substantial effect of the invasive grass on ant, spider, and other invertebrate assemblages. Contrary to our hypothesis, there was no effect of A. gayanus on ant species richness, abundance, or composition, nor were spiders or other invertebrates affected. Instead the change in weather conditions with season was more important in structuring the local invertebrate assemblages. Change in habitat complexity was most pronounced vertically, rather than horizontally at ground level, thus although there was a clear difference in the vertical structure between invaded and noninvaded habitats, the limited invertebrate response to different A. gayanus densities suggests some invertebrates are less sensitive to vertical changes in vegetation structure.