关键词： Entropy   Elements   Lattices   Molecular structure   Power  

摘要： In this paper we consider 13 information and topological indices based on the distance in a molecular graph with respect to their discrimination power. The numerical results of discriminating tests on 3 490 528 trees up to 21 vertices are given. The indices of the highest sensitivity are listed on the set of 1528 775 alkane trees. The discrimination powers of indices are also examined on the classes of 849 285 hexagonal, 298 382 square, and 295 365 triangular simply connected animals. The first class of animals corresponds to the structural formulas of planar benzenoid hydrocarbons. The values of all indices were calculated for all classes of animals as well as for the united set of 1443 032 animals. The inspection of the data indicates the great sensitivity of four information indices and one topological index.

关键词： Bruchidae   germination   herbivory   review   seed beetle  

摘要： Large mammalian herbivores are both predators and dispersers of Acacia seeds. While some of the seeds are destroyed during passage through the herbivore's digestive tract, others are defecated unharmed. Ingestion by large herbivores facilitates germination by scarification of the seed coat. The extent of the influence of herbivores on seed dispersal and germination depends on seed retention time and tooth size, which are both positively correlated with body size. Infestation by bruchid beetles (Bruchidae) reduces Acacia germination. Herbivores may reduce bruchid infestation in several ways. Larvae in recently infested seeds are killed by stomach acids penetrating the seed through the larval entry hole. Seeds that are partly excavated by burrowing larvae in more advanced stages may be crushed by the herbivore's teeth. Lastly, but probably most crucially, herbivores simply remove seeds from the natal tree prior to infestation or at least prior to reinfestation. The timing and magnitude of herbivory is crucial for both the reduction of bruchid infestation and Acacia seedling establishment. Although it is widely agreed that a three-way interaction exists between bruchid beetles, Acacia trees and large mammalian herbivores, it is also apparent that the relationship is highly complex and is not yet completely understood.

关键词： paperbark tree   arthropod abundance   Oxyops vitiosa   weed biological control  

摘要： Melaleuca quinquenervia (Cav.) S. T. Blake, the broad-leaved paperbark tree, has invaded ca. 202,000 ha in Florida, including portions of the Everglades National Park. We performed prerelease surveys in south Florida to determine if native or accidentally introduced arthropods exploit this invasive plant species and assess the potential for higher trophic levels to interfere with the establishment and success of future biological control agents. Herein we quantify the abundance of arthropods present on the above-ground portions of saplings and small M. quinquenervia trees at four sites. Only eight of the 328 arthropods collected were observed feeding on M. quinquenervia. Among the arthropods collected in the plants adventive range, 19 species are agricultural or horticultural pests. The high percentage of rare species (72.0%), presumed to be transient or merely resting on the foliage, and the paucity of species observed feeding on the weed, suggests that future biological control agents will face little if any competition from pre-existing plant-feeding arthropods.

关键词： V-2 receptor   vasotocin receptor   mesotocin receptor   cAMP accumulation   skin   pelvic patch  

摘要： In most amphibians, [Arg(8)] vasotocin (VT) has an antidiuretic effect that is coupled to the activation of adenylate cyclase. In contrast, mesotocin (MT) has a diuretic effect and acts via the inositol phosphate/calcium signaling pathway in amphibians. To further clarify the mechanisms of VT and MT activation, we report the molecular cloning of a VT receptor (VTR) and a MT receptor (MTR) from the Japanese tree frog, Hyla japonica. Tree frog VTR or MTR cDNA encoded 363 or 389 amino acids, and their amino acid sequences revealed close similarity to the mammalian vasopressin V-2 (51-52% identity) or toad MT (94% identity) receptors, respectively. Using CHO-K1 cells transfected with tree frog VTR, we observed elevated concentrations of intracellular cAMP following exposure of the cells to VT or other neurohypophysial hormones, whereas the cells transfected with MTR did not exhibit altered cAMP concentrations. The cells transfected with VTR exhibited the following efficiency for cAMP accumulation: VT = hydrin 1 greater than or equal to vasopressin greater than or equal to hydrin 2 > MT = oxytocin > isotocin. VTR or MTR mRNA exhibits a single 2.2- or 5.5-kb transcription band, respectively, and both are expressed in various tissues. VTR mRNA is clearly expressed in brain, heart, kidney, pelvic patch of skin, and urinary bladder, whereas brain, fat body, heart, kidney, and urinary bladder express MTR mRNA. Specifically, VTR mRNA in the pelvic patch or MTR mRNA in the dorsal skin is present at elevated levels in the skin. Characteristic distribution of VTR and MTR on osmoregulating organs indicates the ligands for these receptors would mediate a variety of functions. Further, the distribution of VTR in the skin would make the regional difference on cutaneous water absorption in response to VT in the Japanese tree frog. (C) 2003 Elsevier Science (USA). All rights reserved.

关键词： Amino Acid Sequence   fossil record   Cnidaria   branches   variable ratio   Metazoa   evolution   sponges   Choanoflagellata   Animalia  

摘要： A phylogenetic framework is essential for understanding the origin and evolution of metazoan development. Despite a number of recent molecular studies and a rich fossil record of sponges and cnidarians, the evolutionary relationships of the early branching metazoan groups to each other and to a putative outgroup, the choanoflagellates, remain uncertain. This situation may be the result of the limited amount of phylogenetic information found in single genes and the small number of relevant taxa surveyed. To alleviate the effect of these analytical factors in the phylogenetic reconstruction of early branching metazoan lineages, we cloned multiple protein-coding genes from two choanoflagellates and diverse sponges, cnidarians, and a ctenophore. Comparisons of sequences for alpha-tubulin, beta-tubulin, elongation factor 2, HSP90, and HSP70 robustly support the hypothesis that choanoflagellates are closely affiliated with animals. However, analyses of single and concatenated amino acid sequences fail to resolve the relationships either between early branching metazoan groups or between Metazoa and choanoflagellates. We demonstrate that variable rates of evolution among lineages, sensitivity of the analyses to taxon selection, and conflicts in the phylogenetic signal contained in different amino acid sequences obscure the phylogenetic associations among the early branching Metazoa. These factors raise concerns about the ability to resolve the phylogenetic history of animals with molecular sequences. A consensus view of animal evolution may require investigations of genome-scale characters.

关键词： 石家庄征宇动物药业有限公司   概况   销售业绩   企业   温树勋   人物访谈  

关键词： forestry   height   marsupial   patch quality   patch size  

摘要： 1. In south-eastern Australia, browsing of commercial tree seedlings by mammalian herbivores in plantation forestry incurs a large economic cost to the industry, through its effect on tree survival, growth and form. In the absence of lethal methods to control herbivore populations, appropriate manipulation of vegetation through silvicultural management may reduce browsing but it relies on understanding the feeding responses of the herbivores to such changes. 2. We evaluated the extent to which vegetation patch characteristics affected browsing of pine Pinus radiata seedlings by generalist mammalian herbivores, including red-bellied pademelons Thylogale billardierii , Bennett's wallaby Macropus rufogriseus rufogriseus and the common brushtail possum Trichosurus vulpecula . 3. In field trials, browsing of pine seedlings was greatest when they were located in patches of high quality, i.e. palatable short vegetation (grass), intermediate in high-quality tall vegetation (Lomandra longifolia ) and least in low-quality tall vegetation (bracken and shrub). Patch structure also affected browsing: in low-quality patches pine seedlings were browsed more in short vegetation patches (12-24 cm shorter than the seedling) than in tall vegetation patches (at least as tall as the seedling). This difference was at least partly because herbivores took, on average, 2 weeks longer to locate seedlings in tall than in short vegetation. 4. In trials with captive red-bellied pademelons and brushtail possums, pine seedlings were browsed similarly in small short grass and soil patches. However, when these patches were large and spatially separated, they were browsed more in short grass than soil patches. Selection at the patch or individual plant level therefore depended on spatial scale and proximity of the patches. 5. Synthesis and applications . The influence of patch characteristics on browsing has the potential to be exploited for the management of browsing damage to commercially importan

关键词： dioecy   Forchhammeria   herbivory   Murgantia   plant/insect interactions  

摘要： The effects of sex and age of a dioecious tree, Forchhammeria pallida , on the survival and development of a Mexican harlequin bug, Murgantia varicolor , were examined. In the laboratory, bugs reared on fruits or fruits and leaves developed rapidly and had a high rate of survivorship, whereas bugs reared on leaves alone developed slowly after the second instar and died by the fifth instar. Murgantia varicolor showed a preference for leaves from juvenile plants over leaves from mature plants, and bugs reared on leaves from juvenile plants survived significantly longer than those reared on leaves from mature plants. Murgantia varicolor showed no preference for feeding on leaves of mature male versus mature female plants. In the field, M. varicolor occurred on male, female and juvenile plants. Although nymphs were less common on male than female F. pallida , their presence in substantial numbers shows that M. varicolor oviposits on both male and female plants. However, adult M. varicolor were rare on male plants. This result is supported by the inability of nymphs to complete their development on vegetative parts of F. pallida in the laboratory. These observations suggest that dioecy in F. pallida may be disruptive to populations of M. varicolor.

关键词： EICA   host-range   invasions  

摘要： Invasive plants are often larger in their introduced range compared to their native range. This may reflect an evolved reduction in defense and increase in growth in response to low herbivory in their introduced range. Key elements of this scenario include genetic differences in defense and growth yet uniformly low rates of herbivory in the field that dissociate defense and herbivore damage for alien species. We conducted a laboratory experiment with Melanoplus angustipennis C Grasshoppers and Chinese Tallow Tree seedlings (Sapium sebiferum) from its native range (China) and its introduced range (Texas, USA) where it is invasive. We caged crrasshoppers with pairs of Sapium seedlings from the same continent or different continents. The amounts of leaf area removed from Texas and China seedlings, and their height growth rates, were indistinguishable when both seedlings in the pair were from the same continent. However, when grasshoppers had a choice between seedlings from different continents, they removed more Texas Sapium foliage than China Sapium foliage and height growth rates were higher for China Sapium seedlings compared to Texas seedlings. Grasshopper Growth rates increased with greater Sapium foliage consumption. In a common garden in Texas, Sapium seedlings from Texas grew 40% faster than those from China. Chewing insect herbivores removed little Sapium foliage in the field experiment. Although grasshoppers preferred to feed on Texas Sapium when offered a choice in the laboratory, extremely low herbivory levels in the field may have allowed the Texas seedlings to outperform the China seedlings in the common garden. These results demonstrate post-invasion genetic differences in herbivore resistance and growth of an invasive plant species together with a decoupling of defense and herbivore choice in the introduced range.

关键词： flood plain   habitat structure   mammals   Miombo   plantations   Tanzania   teak  

摘要： Tropical dry woodlands provide important natural resources for both humans and wildlife, but woodlands situated outside protected areas are vulnerable to over-exploitation. In the Kilombero Valley, Tanzania, miombo woodland is converted into teak plantations and small, private farms, but the impact of this habitat change on wildlife populations is poorly understood. We assessed the frequency of habitat use of large mammals in teak plantations of different age during the wet season. Vegetation structure varied significantly with age;older plantations had larger trees, a more extensive shrub layer and a well-developed leaf litter. Younger plantations had smaller trees and larger areas of short vegetation and bare ground. Track surveys revealed that older plantations were predominantly used by bush pig Potamochoerus larvatus, bushbuck Tragelaphus scriptus and duiker (Cephalophus harveyii, C. natalensis or Sylvicarpa grimmia), whilst the younger plantations were used by open-habitat specialists such as warthog Phacochoerus africanus and waterbuck Kobus ellipsiprymnus. Proximity to the flood plain was also found to be important and plantations nearest this area contained significantly more tracks of large grazers and bulk feeders, reflecting use by zebra Equus burchelli, buffalo Syncerus caffer and waterbuck. Areas of miombo woodland that have been converted into teak plantations provide suitable habitat for wildlife in the Kilombero Valley, but their conservation value diminishes with time. Future management should therefore aim to maintain the patchwork of miombo woodland and teak plantations in order to provide suitable habitat for a range of wildlife. Where possible, teak plantations should not be situated close to the boundary of the miombo woodland and flood plain because this habitat is an important wet season refuge for wildlife during the wet season.