关键词： Fleas   Parasitism   Mammals   Species diversity   Rainfall   Flea infestations   Ectoparasites   Host parasite relationships   Animal communities  

摘要： The relative importance of environmental factors and host factors in explaining variation in prevalence and intensity of flea parasitism in small mammal communities is poorly established. We examined these relationships in an East African savanna landscape, considering multiple host levels: across individuals within a local population, across populations within species, and across species within a landscape. We sampled fleas from 2,672 small mammals of 27 species. This included a total of 8,283 fleas, with 5 genera and 12 species identified. Across individual hosts within a site, both rodent body mass and season affected total intensity of flea infestation, although the explanatory power of these factors was generally modest (<10%). Across host populations in the landscape, we found consistently positive effects of host density and negative effects of vegetation cover on the intensity of flea infestation. Other factors explored (host diversity, annual rainfall, anthropogenic disturbance, and soil properties) tended to have lower and less consistent explanatory power. Across host species in the landscape, we found that host body mass was strongly positively correlated with both prevalence and intensity of flea parasitism, while average robustness of a host species to disturbance was not correlated with flea parasitism. Cumulatively, these results provide insight into the intricate roles of both host and environmental factors in explaining complex patterns of flea parasitism across landscape mosaics.

关键词： Animals   Arthropods   Birds   Ethiopia   Predatory Behavior   Trees  

摘要： Bird and arthropod predation is often associated with natural pest control in agricultural landscapes, but the rates of predation may vary with the amount of tree cover or other environmental factors. We examined bird and arthropod predation in three tree-rich and three tree-poor landscapes across southwestern Ethiopia. Within each landscape we selected three tree-rich and three tree-poor homegardens in which we recorded the number of tree species and tree stems within 100 x 100 m surrounding the central house. To estimate predation rates, we attached plasticine caterpillars on leaves of two coffee and two avocado shrubs in each homegarden, and recorded the number of attacked caterpillars for 7-9 consecutive weeks. The overall mean daily predation rate was 1.45% for birds and 1.60% for arthropods. The rates of arthropod predation varied among landscapes and were higher in tree-poor landscapes. There was no such difference for birds. Within landscapes, predation rates from birds and arthropods did not vary between tree-rich and tree-poor homegardens in either tree-rich or tree-poor landscapes. The most surprising result was the lack of response by birds to tree cover at either spatial scale. Our results suggest that in tree-poor landscapes there are still enough non-crop habitats to support predatory arthropods and birds to deliver strong top-down effect on crop pests.

关键词： biotic resistance   food availability   grasslands   invasion   rodent   seed consumption  

摘要： Biotic resistance has been invoked as a major barrier to woody species invasion, although the role of resident generalist consumers and their interaction with seed availability in a local community has received little attention. We assessed tree seed consumption by rodents under two different scenarios: (i) We documented in field spatio-temporal patterns of seed predation by native rodents on two exotic tree species, Gleditsia triacanthos or honey locust' and Robinia pseudoacacia or white locust' (family Leguminosae), in five grassland habitats of the Inland Pampa, Argentina. (ii) We conducted laboratory feeding trials to evaluate tree seed consumption in the presence (cafeteria-style feeding trials) and in the absence (non-choice feeding trials) of alternative food supplies. Seed predation was generally higher for Robinia than for Gleditsia seeds, both in field and laboratory conditions. For both tree species, seed predation varied between habitats and seasons and was higher in the native tussock grassland than in the remaining studied communities, whereas the crop field showed the lowest levels of consumption along with the absence of captured rodents. Seed consumption of Gleditsia and Robinia among the four grassland communities (which did not differ in rodent abundance) was negatively associated with the availability of alternative food. Laboratory feeding trials showed a higher consumption of Gleditsia seeds in the non-choice than in the cafeteria-style feeding trials, while the consumption of Robinia seeds did not differ in the absence or presence of alternative seeds. These patterns indicate that the contribution of resident granivores to invasion resistance might depend on colonizer species identity, recipient community type and season of the year. We suggest that rodent preferences for different invader seeds will interact with the availability of alternative food in the local habitat in influencing the amount of predator-mediated biotic resistance to invas

关键词： biogeography   determinants of plant community diversity and structure   disturbance   dominant species   drought   fire   functional traits   grass community   grazing   phylogeny  

摘要： Grazing and fire are disturbances integral to the evolution and maintenance of savanna grasslands. Humans are altering or completely eliminating these disturbance regimes at a global scale, with important consequences for savanna ecosystem structure and function. It is unknown whether the alteration of these disturbance regimes will have similar effects on grass communities of savanna grasslands in different geographic regions that vary in their biogeographic and evolutionary histories, as well as in the diversity of extant grazers. Here, we examined the effects of large herbivore loss on different aspects of grass community structure - taxonomic, phylogenetic and functional - across a range of fire frequencies in C-4-dominated mesic savanna grassland sites of North America (Konza Prairie Biological Station, Kansas, USA) and South Africa (Kruger National Park). The goal of the study was to determine whether the loss of large herbivores exerted a consistent effect on the grass communities of two physiognomically similar grasslands with different biogeographic and grazing histories. The removal of large herbivores resulted in divergent responses in the grass communities at Konza and Kruger that was consistent across fire treatments. At Konza, there was a rapid and significant response to grazing exclusion while the response was muted and transient at Kruger. Functional syndromes associated with grazing resistance were generally conserved across sites, and it was the functional strategies of the dominant species at each site that drove the divergent responses. Further, our study supports the hypothesis that grazing and aridity may be selective forces that act in parallel as those species that were grazing resistant also occupied drier ***. Our study demonstrates that savanna grassland communities with different biogeographic and grazing histories respond differently to the removal of large herbivores and that climate, fire and grazing are interactive force

关键词： Euarchonta   Euarchontoglires   phylogenomics   tree shrews  

摘要： The well-accepted Euarchonta grandorder is a pruned version of Archonta nested within the Euarchontoglires(or Supraprimates)*** present,it includes tree shrews(Scandentia),flying lemurs(Dermoptera)and primates(Primates).Here,a phylogenomic dataset containing 1912 exons from 22 representative mammals was compiled to investigate the phylogenetic relationships within this *** analyses and hypothesis testing suggested that tree shrews can be classified as a sister group to Primates or to Glires or even as a basal clade within *** analyses of both modified and original previously published datasets found that the phylogenetic position of tree shrews is *** also found that two of three exonic indels reported as synapomorphies of Euarchonta in a previous study do not unambiguously support the monophyly of such a ***,the monophyly of both Euarchonta and Sundatheria(Dermoptera+Scandentia)are *** dating and divergence rate analyses suggested that the ancestor of Euarchontoglires experienced a rapid divergence,which may cause the unresolved position of tree shrews even using the whole genomic data.

关键词： Brazil   cerradao   Cerrado   fire ecology   Gracilinanus agilis   Rhipidomys macrurus   survival  

摘要： Fire is a major form of disturbance in terrestrial ecosystems, mainly in tropical savannas. In these ecosystems, the effects of large wildfires are potentially high on small and relatively less mobile animals, like small mammals. We investigated the effects of an extensive wildfire (approximate to 6,240 ha) in September 2011 on populations of 2 arboreal-scansorial small mammals-the gracile mouse opossum, Gracilinanus agilis, and the long-tailed climbing mouse, Rhipidomys macrurus-in 4 savanna woodland patches (1 burned, 3 unburned) of the highly threatened Brazilian Cerrado. We assessed population densities from 2009 to 2013 and for G. agilis, we estimated apparent survival and recapture probabilities with Cormack-Jolly-Seber models. Both species showed strong, negative fire responses, including sudden collapse and slow recovery (at least more than 1 year). These observed responses were probably a consequence of both the phytophysiognomic features of the habitat and severity of the fire with the resulting changes on the vertical structure of vegetation. The studied species of Cerrado forested formations were not as resilient to fire disturbance as typical species from savanna or temperate woodlands. As a consequence of human activities and climate changes, fire events are predicted to become larger and more frequent in the Brazilian Cerrado. Therefore, it is imperative to create new management strategies to protect forested physiognomies from fire, especially cerradao, which is very fire sensitive and has a limited and scattered distribution in the landscape.

关键词： Biological invasion   establishment   exotic   natural enemy release   pollination syndrome   pre-dispersal seed predation   weed  

摘要： AimInteractions with pollinators and pre-dispersal seed predators are important determinants of reproductive output and could influence the success of plant species introduced to areas outside their native range. We identified the role of these interactions in determining reproductive output and invasion outcomes for species of Australian Acacia introduced to New Zealand. LocationAustralia and New Zealand. MethodsWe studied three species of Australian Acacia with different invasion success in New Zealand. In both Australia and New Zealand, we measured pollination success as the number of pods per inflorescence and the proportion of aborted seeds per pod, determined losses to pre-dispersal seed predators, and measured overall seed output. For each species, we compared performance in New Zealand with that in Australia, then examined whether there was any variation among species in their relative performance in each country. ResultsThe number of pods per inflorescence and proportion of seeds aborted were similar in each country and among species. There was little difference in pre-dispersal seed predation rate between Australia and New Zealand for Acacia dealbata, an invasive species, and Acacia baileyana, a species widely naturalized in New Zealand. However, pre-dispersal seed predation rate was lower in New Zealand for Acacia pravissima, currently considered to be a casual species there. Both the invasive A. dealbata and the casual A. pravissima produced more seeds per tree in New Zealand than Australia. Main conclusionsDifferences in reproductive success between the native and introduced range could not explain the differences in invasion success among the three Acacia species. Although per capita reproductive output was higher in New Zealand for two species, neither mutualistic interactions with pollinators nor antagonistic interactions with pre-dispersal seed predators explained those differences. The high seed output of A. pravissima suggests it has the potential

关键词： 环境科学专业   环保科技   观鸟   二至   参与人员   知识目标   鸟叫   在乡下   记录单   细节特征  

摘要： 一、活动名称＂初夏的动静＂——探访动物园中的鸟和树二、参与人员1.儿童：5人,小学二至四年级学生,以二年级为主;2.教师：1人,环境科学专业、环保科技教师;3.其他：随行家长4人、活动配合工作人员2人。三、活动目标1.知识目标（1）在水禽湖附近观鸟窝、听鸟叫、观察鸟,识别出鸟及鸟巢的类型,巩固相关知识。

关键词： diversity   euglossinen   biogeography   neotropics   pollinators  

摘要： The Neotropical savanna is characterized by a set of different phytophysiognomies occurring in a wide expanse of Brazilian lands. Based on the known higher diversity of orchid bees in forests rather than in savanna formations, we hypothesized that the occurrence of forest formations inside the Brazilian savanna increases the diversity of euglossine bees in that domain and that there are species more associated with these environments. To test this hypothesis, we sampled the euglossine fauna in eight forest and woody savanna remnants and analyzed their community structure. We sampled 1,010 males of 13 species of orchid bees. Bee abundance and species richness ranged from 30 to 341 individuals and from 4 to 12 species, respectively. The forest remnants showed the highest diversity indices and species richness. Our data suggest that some species of Euglossa are mainly associated with forest remnants. We concluded that environmental heterogeneity in the Neotropical savanna contributes to higher diversity of euglossine and that some species are more frequently found in forested habitats. Additionally, considering that some sampled species are typical of the Atlantic and Amazon forests, our data reinforce the hypothesis that forest environments inside the Brazilian savanna can be considered bio-corridors for orchid bees.