关键词： Herbivore   Loxodonta africana   savanna   surface water   Tembe Elephant Park   vegetation impacts   wildlife management  

摘要： Aim Artificial water points are often used in protected savanna ecosystems to maintain populations of large herbivores. However, these interventions lead to increased ranging and foraging pressure and can negatively impact important habitats and species. This study investigated the influence of artificial water provision on the foraging and movement paths of an African elephant population and modelled the impact of changing water availability on sensitive habitat types. Location Tembe Elephant Park (TEP), KwaZulu-Natal, South Africa. Methods We mapped and classified 414 km of elephant movement and foraging paths in a 300-km(2) fenced protected area. The data were analysed to determine the relationship between path size, distribution and distance to water. We also used a logistic modelling approach to explore the predicted effects of removing artificial water points on path distribution. Results Elephant paths were unevenly distributed throughout the habitats of TEP and the most established and heavily used paths were found closest to water. We also discovered a number of elephant 'rest areas' along the paths, which were distinct clearings that tended to be close to water and in sand forest habitat. Our model predicted that the removal of artificial water points would reduce the area crossed by elephant paths by 79%, leading to an 89% reduction in the presence of elephant paths in sand forest. Main conclusions Our study provides further evidence that manipulating surface water availability can be a useful tool for managing large herbivore impacts on vegetation and acts as the basis for further research on the trade-offs between conservation objectives.

关键词： collective behaviour   cue   functional significance   group signalling   treehopper   Umbonia crassicornis  

摘要： Many animal groups respond collectively to environmental cues. To understand the function of collective behaviour, an important first step is to establish how it varies in response to differences in the relevant cues. Because collective action arises from individual decisions, this in turn requires characterizing the behaviour of individual group members. In the treehopper Umbonia crassicornis, offspring live in cylindrical aggregations along a host plant stem. In the presence of a predator, offspring produce synchronized vibrational signals that elicit maternal defence. Predators typically attack the ends of the aggregation;because the mother must approach the predator to defend her offspring, we hypothesized that variation in collective signals reveals not only the predator's presence, but also its location. The defending mother also produces signals, and we hypothesized that maternal cues influence the signalling behaviour of the brood. We simulated predation at either end of the aggregation. In the presence of the mother, ( 1) offspring closer to the predator were more likely to signal and ( 2) more offspring contributed to the group signals when the predator attacked the aggregation at the far end from the mother. Differences in group signals, emerging from position-dependent differences in signalling probability of individual offspring, could be used by the defending mother to determine the end of the aggregation being attacked. A loss of these signalling patterns in the absence of the mother reveals that maternal cues are necessary for the establishment of a reliable relationship between collective signalling and predator location. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

关键词： Botanical anachronism   Megafaunal disclimax   Gymnocladus dioicus   Megafaunal fruit hypothesis   Seed dispersal syndromes  

摘要： The Kentucky coffeetree (Gymnocladus dioicus, Fabaceae) is an ecological paradox. A rare tree in nature in eastern and central North America, G. dioicus produces legumes that are only known to be dispersed by water, but appear similar to fruits consumed and dispersed by elephants and rhinoceros. One would expect the pods to be consumed by livestock, but the pulp and seeds are toxic to cattle and sheep. We examine the puzzle of G. dioicus dispersal in light of its other reproductive and life history characteristics and find that it probably is a botanical anachronism, in terms of both a set of dispersal agents long extinct and habitats, including what we term megafaunal disclimaxes, which have disappeared. Large seeds, the megafaunal gestault of the fruit, a dioecious mating system, and shade-intolerance combined with vigorous cloning suggest a widely dispersed pioneer of Miocene through Pleistocene habitats profoundly altered by large-mammal herbivory. As to what ate it, we can only say there were once many candidates. We hypothesize that the plant is an ecological anachronism, sinking to extinction in the wild.

关键词： climate change   drought   genetic variation   herbivory   mortality   Pinus edulis   pinyon pine   resistance   seedling experiment   selection  

摘要： Current climate models predict a shift to warmer, drier conditions in the southwestern US. While major shifts in plant distribution are expected to follow these climate changes, interactions among species and intraspecific genetic variation rarely have been incorporated into models of future plant distributions. We examined the drought-related mortality of pinyon pine (Pinus edulis) in northern Arizona focusing on trees that showed genetically-based resistance or susceptibility to a nonlethal herbivore, the shoot-boring moth, Dioryctria albovittella. Because moth resistant trees have outperformed susceptible trees during 20 years of study, and herbivory has been shown to increase drought related mortality, we expected higher mortality rates in susceptible trees. However, our field observations and greenhouse experiments showed several unexpected patterns relevant to understanding the consequences of climate change: (1) The mortality of adult P. edulis resistant to the moth was three times higher than the mortality of trees susceptible to the moth. (2) Over a few years, differential mortality caused a shift in stand structure from resistant dominated to equality (3 : 1 resistant : susceptible to 1 : 1). (3) Adult moth resistant trees suffered significantly greater water stress than adult moth susceptible trees, suggesting that variation among the two groups in drought tolerance may be a mechanism for differential mortality. (4) When grown under drought conditions in the greenhouse, seedlings from resistant mothers died sooner than seedlings from susceptible mothers. These data support the hypothesis that drought can act as an agent of balancing selection and that drought resistance is a heritable trait. Taken together, our findings suggest that genetic variation in a population can be an important factor in determining its response to future climate change, and argue for the inclusion of genetics into models developed to understand the consequences of climate change.

关键词： elevated CO2   insect densities   insect herbivory   Kennedy Space Center   leaf production   long-term effects   oak trees   species-specific responses  

摘要： The effects of elevated CO2 on plant growth and insect herbivory have been frequently investigated over the past 20 years. Most studies have shown an increase in plant growth, a decrease in plant nitrogen concentration, an increase in plant secondary metabolites and a decrease in herbivory. However, such studies have generally overlooked the fact that increases in plant production could cause increases of herbivores per unit area of habitat. Our study investigated leaf production, herbivory levels and herbivore abundance per unit area of leaf litter in a scrub-oak system at Kennedy Space Center, Florida, under conditions of ambient and elevated CO2, over an 11-year period, from 1996 to 2007. In every year, herbivory, that is leafminer and leaftier abundance per 200 leaves, was lower under elevated CO2 than ambient CO2 for each of three species of oaks, Quercus myrtifolia, Quercus chapmanii and Quercus geminata. However, leaf litter production per 0.1143 m(2) was greater under elevated CO2 than ambient CO2 for Q. myrtifolia and Q. chapmanii, and this difference increased over the 11 years of the study. Leaf production of Q. geminata under elevated CO2 did not increase. Leafminer densities per 0.1143 m(2) of litterfall for Q. myrtifolia and Q. chapmanii were initially lower under elevated CO2. However, shortly after canopy closure in 2001, leafminer densities per 0.1143 m(2) of litter fall became higher under elevated CO2 and remained higher for the remainder of the experiment. Leaftier densities per 0.1143 m(2) were also higher under elevated CO2 for Q. myrtifolia and Q. chapmanii over the last 6 years of the experiment. There were no differences in leafminer or leaftier densities per 0.1143 m(2) of litter for Q. geminata. These results show three phenomena. First, they show that elevated CO2 decreases herbivory on all oak species in the Florida scrub-oak system. Second, despite lower numbers of herbivores per 200 leaves in elevated CO2, increased leaf production res

关键词： Brushtail possum   Forest management   Temperature datalogger   Tree hollow  

摘要： The article presents research which examines the importance of temperature dataloggers in monitoring tree hollow-using mammals in Tasmania. Radio-telemetry, remote cameras and fiber optics are instruments used to capture the images of these wild animals at Kellevie and Melton Mowbray sites. In addition, metal washer with surgical cotton attached is applied to identify the temperature changes. It found that brushtail possum species showed significant role to the changes of temperature.

关键词： 树鮈   资源开发   标准化研究  

摘要： 树鮈(Tupaia belangeri)作为人类疾病动物模型,被应用于人类医学实验研究的多个领域,如各种类型的病毒性肝炎模型,流感病毒、登革热病毒、轮状病毒、疱疹病毒模型,糖尿病、胆结石、癌症病模型。但是,目前我国用于实验研究的树鮈几乎全都来自野外,对它们的微生物学、寄生虫学、遗传学、环境学等质量标准没有进行控制,它们本身携带的许多病原体会对实验结果的准确性造成影响,这既不符合国家对实验动物许可证管理的要求,也不利于我国实验动物科技工作与国际接轨的发展要求。因此,应该同步开展树鮈资源的开发利用和标准研究,使之纳入实验动物许可证的有效监控和管理,改变目前使用在前、质量控制标准研究在后的被动局面。

关键词： dew   fire   population variation   rodent declines   smoke   species diversity  

摘要： Small mammals were trapped annually in two savanna and two forest plots in cerrado habitats of Noel Kempff Mercado National Park, Santa Cruz, Bolivia, for 5-10 yr. Eighteen species were captured in forest and seven species in savanna. Species numbers and total number of individuals captured were tightly correlated. In forest, species and abundance varied interannually by up to fourfold in one plot and to 100-fold in the other, and showed alternating highs and lows as is typical for small mammals. The largest faunal differences were due not to site differences, but to year differences, with markedly different patterns in forests and savannas. Abundance was not correlated with rainfall overall, but showed correlation in exceptional years of rainfall and ENSO drought. In savanna, species and overall abundance declined without recovery during 3 yr after reaching minimum numbers in 2004. One species, Cavia aperea, became extinct on both plots, and subsequently, apparently on the entire savanna. Both herbivorous and insectivorous species declined together. Rainfall, fire, and flooding do not seem to account for savanna rodent declines. I propose the novel hypothesis that smoke from anthropogenic burning raises nocturnal temperatures and prevents dew formation, and that a decrease in nightly dry season dewfall has been instrumental in rodent declines. Anecdotal and climatic data are consistent with this hypothesis, but it cannot yet be tested.

关键词： Armadillidium vulgare   Feeding rates   Feeding preferences   C:N ratios   Exotic litter   Russian olive   Cottonwood  

摘要： The feeding preferences and consumption rates of the exotic woodlouse Armadillidium vulgare were measured on litters from the autochthonous Rio Grande cottonwood and the exotic Russian olive. When offered a choice between five litter types (green and shed leaves of Russian olive and cottonwood, and fruits of Russian olive), the isopods consumed more of the exotic plant litter (green leaves and the fruits of Russian olive) than of the autochthonous cottonwood. When offered only one diet consumption rates, of green leaves and fruits of Russian olive were again the highest. Feeding was related with N and C:N ratios of the litter, with highest consumption of diets with low and high C:N ratios and lowest consumption of diets with intermediate C:N ratios. The N content was highest (and C:N ratios lowest) on isopods feeding shed leaves of Russian olive. Growth was not related to the amount or the C:N ratio of the food consumed, being highest for animals feeding on shed leaves of cottonwood. Our results show that the consumption patterns and the C and N body composition of the exotic woodlouse A. vulgare are altered when fed with Russian olive litter, suggesting that the replacement of the autochthonous cottonwood by the exotic Russian olive may negatively affect the maintenance of the population of these exotic detritivores in the area. (C) 2009 Elsevier Masson SAS. All rights reserved.

关键词： Acacia   browsing   herbivores   Lake Nakuru  

摘要： Significant differences (P < 0.05) were found in growth of plant height, canopy cover and stem diameter of Acacia xanthophloea trees in fenced plot as compared with unfenced plot both in the wet and in the dry seasons. Finding of this study showed that although heavy browsing reduced the height and canopy of trees, it did not kill any trees and seedling regeneration took place simultaneously. Despite the presence of large herbivores that impact some considerable browsing pressure results indicate that the A. xanthophloea habitat type would continue to remain in balance in the presence of recruitment of seedlings and saplings. The conditions at the time of study indicate that the browsing on A. xanthophloea was not significant and was not serious enough to warrant management intervention at present.