关键词： Burn   Coarse woody debris   Distance of vulnerability   Ground cover   Peromyscus   Reithrodontomys  

摘要： Following decades of fire suppression many oak-pine savanna ecosystems have shifted to close-canopied forests. Restoration of these ecosystems to their savanna condition is seen as a way to reduce woody species encroachment and dangerous fuel loads, and restore community species composition. The management practices to achieve these goals typically involve thinning and prescribed fire. We assessed how thinning to reduce basal area combined with frequent prescribed fire influenced small mammal communities and their habitat. We focused on six habitat variables that can influence small mammal abundance and species composition: stand basal area of live trees and snags, volume of coarse woody debris, percent ground cover, forest floor depth, and distance of vulnerability, a measure of understory vegetation structure and animal vulnerability to predators. Although savanna restoration reduced basal area by 80%, there was no change in snag density or coarse woody debris volume. Savanna restoration significantly increased the ground cover of graminoids, forbs, bare ground, and down woody debris and reduced forest floor depth and distance of vulnerability. These habitat changes likely contributed to the significant differences between small mammal communities in restored and non-restored stands. Restoration treatments caused a large increase in abundance of White-footed Mouse (Peromyscus leucopus) and important changes in community assemblages. Least Shrew (Cryptotis parva), Fulvous Harvest Mouse (Reithrodontomys fulvescens), Eastern Harvest Mouse (R. humulis), and Hispid Cotton Rat (Sigmodon hispidus) were caught only in restored stands, while House Mouse (Mus musculus), Plains Harvest Mouse (R. montanus), and Texas Mouse (P. attwateri) were caught only in non-restored stands. (C) 2017 Elsevier B.V. All rights reserved.

关键词： BEF-China   biodiversity and ecosystem functioning   climatic niche   functional traits   fungal pathogens   plant-herbivore interactions  

摘要： Herbivores and fungal pathogens are key drivers of plant community composition and functioning. The effects of herbivores and pathogens are mediated by the diversity and functional characteristics of their host plants. However, the combined effects of herbivory and pathogen damage, and their consequences for plant performance, have not yet been addressed in the context of biodiversity-ecosystem functioning research. We analyzed the relationships between herbivory, fungal pathogen damage and their effects on tree growth in a large-scale forest-biodiversity experiment. Moreover, we tested whether variation in leaf trait and climatic niche characteristics among tree species influenced these relationships. We found significant positive effects of herbivory on pathogen damage, and vice versa. These effects were attenuated by tree species richnessbecause herbivory increased and pathogen damage decreased with increasing richnessand were most pronounced for species with soft leaves and narrow climatic niches. However, herbivory and pathogens had contrasting, independent effects on tree growth, with pathogens decreasing and herbivory increasing growth. The positive herbivory effects indicate that trees might be able to (over-)compensate for local damage at the level of the whole tree. Nevertheless, we found a dependence of these effects on richness, leaf traits and climatic niche characteristics of the tree species. This could mean that the ability for compensation is influenced by both biodiversity loss and tree species identityincluding effects of larger-scale climatic adaptations that have been rarely considered in this context. Our results suggest that herbivory and pathogens have additive but contrasting effects on tree growth. Considering effects of both herbivory and pathogens may thus help to better understand the net effects of damage on tree performance in communities differing in diversity. Moreover, our study shows how species richness and species characteristics

关键词： plant architecture   structural defences   herbivory   cage architecture   spinescence   bite rate  

摘要： 1. Where large browsers are abundant, the survival of trees depends on their ability to deploy defences, either chemical or structural. Structural defences include the arrangement of dense and intricate architecture, termed ` cage' architecture. Previous studies showed that trees developing in herbivore-rich environments tend to have more cage architecture but its precise effect on mammalian herbivores remains unknown. 2. In this paper, we experimentally test how cage architecture affects the bite rate of goats, a generalist mammalian herbivore. 3. We selected 11 palatable tree species with contrasting architectures. We described their caginess using an index combining spinescence and woodiness of their stems. Finally, we evaluated how the caginess of trees slows down herbivores when feeding on the inner leaves in tree crowns. 4. We observed that the bite rate of goats on inner leaves of the cagiest trees was so severely reduced that they could not satisfy their daily nutritional requirements. We discuss how this could affect the preference of wild herbivores for less cagy trees, especially at the end of the dry season.

关键词： camera trap   Minas Gerais   occupancy analysis   secondary vegetation  

摘要： Debate about the conservation value of secondary habitats has tended to focus on tropical forests, increasingly recognizing the role of secondary forests for biodiversity conservation. However, there remains a lack of information about the conservation value of secondary savannas. Here, we conducted a camera trap survey to assess the effect of secondary vegetation on large mammals in a Brazilian Cerrado protected area, using a single-season occupancy framework to investigate the response of individual species (species-level models) and of all species combined (community-level models). In addition, we investigated the cost effectiveness of different sampling designs to monitor globally threatened species in the study area. At the community level, savanna that regenerated from eucalyptus plantation had similar occupancy estimate as old growth areas. At the species level, none of the ten species individually assessed seemed to respond to succession stage, with greater support for the effect of other covariates on occupancy, such as distance from water and vegetation physiognomy. These results demonstrate that secondary vegetation does not appear to negatively impact large mammals in the study area and suggest that, given a favorable context, Cerrado mammals can recolonize and use secondary savannas that regenerated from clearcut. However, our study area should be considered a best-case scenario, as it retained key ecological attributes of high-value secondary habitats. Our simulations showed that a sampling design with 60 camera trap sites surveyed during nine occasions is appropriate to monitor most globally threatened species in the study area, and could be a useful starting point for new monitoring initiatives in other Cerrado areas. RESUMO O debate sobre a importancia de habitats secundarios para a conservacAo tende a focar em florestas tropicais, existindo evidencia consideravel sobre o papel das florestas secundarias na manutencAo da biodiversidade. Entretanto, p

关键词： α-淀粉酶   节肢动物   系统进化树   序列分析  

摘要： 目的:构建节肢动物α-淀粉酶的系统进化树,探讨其进化关系,找出进化树中聚类在一起的α-淀粉酶的特异性序列。方法:在美国国立生物技术信息中心(National Center for Biotechnology Information,NCBI)数据库中选取了56个节肢动物的α-淀粉酶氨基酸序列,利用CLUSTALX2.0进行序列比对、MEGA6.0建立进化树,通过BOXSHADE找到聚类的α-淀粉酶特异性序列。结果:56个α-淀粉酶聚类成A、B、C、D四大簇,A簇特异性序列为"VD NHD NQ",B簇特异性序列为"ID NHD NX",C簇特异性序列为"ID NHD NQ",D簇特异性序列为"XGN NHD X"。A、B、C、D四簇都含有保守的NHD(天冬酰胺-组氨酸-天冬氨酸)序列,但序列两端氨基酸种类不同。结论:56个节肢动物α-淀粉酶分为4簇,每簇都有其特异性序列,但都含有保守序列NHD。

关键词： arthropod phylogenetics   common garden   community genetics   community phylogenetics   foundation species   hybridization  

摘要： Although hybridization in plants has been recognized as an important pathway in plant speciation, it may also affect the ecology and evolution of associated communities. Cottonwood species (Populus angustifolia and ***) and their naturally occurring hybrids are known to support different plant, animal, and microbial communities, but no studies have examined community structure within the context of phylogenetic history. Using a community composed of 199 arthropod species, we tested for differences in arthropod phylogenetic patterns within and among hybrid and parental tree types in a common garden. Three major patterns emerged. (1) Phylogenetic diversity (PD) was significantly different between arthropod communities on hybrids and Fremont cottonwood when pooled by tree type. (2) Mean phylogenetic distance (MPD) and net relatedness index (NRI) indicated that communities on hybrid trees were significantly more phylogenetically overdispersed than communities on either parental tree type. (3) Community distance (D-pw) indicated that communities on hybrids were significantly different than parental species. Our results show that arthropod communities on parental and hybrid cottonwoods exhibit significantly different patterns of phylogenetic structure. This suggests that arthropod community assembly is driven, in part, by plant-arthropod interactions at the level of cottonwood tree type. We discuss potential hypotheses to explain the effect of plant genetic dissimilarity on arthropod phylogenetic community structure, including the role of competition and environmental filtering. Our findings suggest that cottonwood species and their hybrids function as evolutionarily significant units (ESUs) that affect the assembly and composition of associated arthropod communities and deserve high priority for conservation.

关键词： metabolic theory of ecology   macroevolution   phylogenetic comparative methods   allometry  

摘要： Metabolism is the link between ecology and physiology-it dictates the flow of energy through individuals and across trophic levels. Much of the predictive power of metabolic theories of ecology derives from the scaling relationship between organismal size and metabolic rate. There is growing evidence that this scaling relationship is not universal, but we have little knowledge of how it has evolved over macroevolutionary time. Here we develop a novel phylogenetic comparative method to investigate how often and in which clades the macroevolutionary dynamics of the metabolic scaling have changed. We find strong evidence that the metabolic scaling relationship has shifted multiple times across the vertebrate phylogeny. However, shifts are rare and otherwise strongly constrained. Importantly, both the estimated slope and intercept values vary widely across regimes, with slopes that spanned across theoretically predicted values such as 2/3 or 3/4. We further tested whether traits such as ecto-/endothermy, genome size, and quadratic curvature with body mass (i.e., energetic constraints at extreme body sizes) could explain the observed pattern of shifts. Though these factors help explain some of the variation in scaling parameters, much of the remaining variation remains elusive. Our results lay the groundwork for further exploration of the evolutionary and ecological drivers of major transitions in metabolic strategy and for harnessing this information to improve macroecological predictions.

关键词： Basal resources   Mycorrhiza   Pulse labeling   Rhizodeposits   Stable isotopes  

摘要： Root-derived resources are receiving increased attention as basal resources for soil animal food webs. They predominantly function as carbon and energy resources for microbial metabolism in the rhizosphere, however, root-derived nitrogen may also be important. We explored both the role of root-derived carbon (C) and nitrogen (N) for the nutrition of soil animal species. Using C-13 and N-15 pulse labeling we followed in situ the flux of shoot-derived C and N into the soil animal food web of young beech (Fagus sylvatica) and ash (Fraxinus excelsior) trees. For labeling with C-13, trees were exposed to increased atmospheric concentrations of (CO2)-C-13 and for labeling with N-15 leaves were immersed in a solution of (CaNO3)-N-15. Twenty days after labeling root-derived N was detected in each of the studied soil animal species whereas incorporation of root-derived C was only detected in the ash rhizosphere. More root-derived N was incorporated into soil animals from the beech as compared to the ash rhizosphere, in spite of the higher N-15 signatures in fine roots of ash as compared to beech. The results suggest that soil animal food webs not only rely on root C but also on root N with the contribution of root N to soil animal nutrition varying with tree species. This novel pathway of plant N highlights the importance of root-derived resources for soil animal food webs. (C) 2017 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

关键词： Fermentation   Gas production   Chemical composition   Prickly pear  

摘要： In production systems of prickly pear fruit and prickly pear cactus, significant amounts of pruned material, which could be used as an ingredient in animal feeding, is generated. The aim of this study was to measure the nutrient content, fermentation kinetics and in vitro digestibility of eleven cultivars of cladodes of prickly pear cactus. The fermentation was measured indirectly using the gas production technique, where 500 mg of DM substrate (prickly pear cactus cultivars) were placed in amber glass flasks of 125 mL with 90 mL of ruminal inoculum under a continuous flow of CO2. Flasks were hermetically wrapped up with a rubber stopper and a metal ring, and were placed in a water bath at 39 degrees C. The fermentation gas pressure was measured using a monometer at 0, 2, 4, 6, 8, 12, 16, 20, 24, 32, 38, 50 and 72 h incubation. Results show that the chemical composition ranged between (g kg(-1) DM): 64 and 160 g kg(-1) dry matter (DM), 137-293 g kg(-1) DM ash, 52-101 g kg(-1) DM crude protein, 3-22 g kg(-1) DM ether extract, 251-393 neutral detergent fiber and 132-192 acid detergent fiber. The gas volume was different (p < 0.05) among cultivars, with the Red Vigor cultivar having the largest volume at 378 mL g(-1) DM. The highest volume of gas was produced during the first 24 h in on average 67 % of the total produced. The in vitro DM digestibility displayed values of up to 82 % in the Roja Pelota cultivar. It can be concluded that the cladodes of prickly pear cactus from different cultivars can be used in animal feed for its good rumen fermentation characteristics.

关键词： Zinc oxide nanoparticles   Reactive oxygen species   Oxidative stress   Alginate   Gum acacia   Horse   Lipid peroxidation   MDA   Hemolytic activity  

摘要： Zinc oxide nanoparticles are important nanomaterials currently under research due to their applicability in nanomedicine. Toxicity of ZnO NPs has been extensively studied and has been shown to affect various cell types and animal systems. In this study, we investigated hemolytic potential and oxidative stress inflicted by ZnO NPs and ZnO NPs-loaded-sodium alginate-gum acacia hydrogels on horse erythrocytes and African green monkey kidney (Vero) cells. Our study provides a better understanding of the hemolytic and oxidative effects of interaction of ZnO NPs and ZnO NPs released from polymeric hydrogels with the biological system. Remarkable aggregation of erythrocytes was noted in the higher concentration of ZnO NPs treated erythrocytes as compared to erythrocytes treated with ZnO NPs-loaded hydrogels. ZnO NPs-loaded hydrogels treated Vero cells significantly reduced oxidative stress as evidenced by less malondialdehyde production as compared to that of ZnO NPs treated cells. Normal horse erythrocytes when treated with ZnO NPs in in vitro condition undergo oxidative damage, and contribute in augmenting the toxicity. We demonstrated that polymeric ZnO NPs reduced the undesirable effects provoked by ZnO NPs on mammalian cells. (C) 2017 Elsevier B.V. All rights reserved.