Intraguild niche partitioning in granivorous birds from the late past

Niche partitioning is a widespread ecological strategy within trophic guilds,ensuring the coexistence of sympatric species by reducing interspecific competition.Stable isotope analysis of carbon and nitrogen and isotopic niche metrics(width and overlap)are used as a proxy to investigate niche partitioning among species of a guild.In our study,we investigated if niche partitioning was an ecological mechanism contributing to the coexistence of granivorous birds from the same geographic region along time,employing an isotopic approach.We sampled and isotopically analyzed(δ^(13)C andδ^(15)N values)wing feathers from 58 specimens of granivorous birds collected between 1900 and 1966 in southeastern Brazil.We grouped birds according to the main habitat type used by them(forest:Cyanoloxia brissonii,Leptotila and Leptotila verreauxi;and grassland:Columbina squammata and Sicalis flaveola).We used the Isotopic Richness(IRic)metric to measure the isotopic niche width and the Isotopic Similarity(ISim)and Isotopic Nestedness(INes)metrics to measure the niche overlap between groups and species.The results of low isotopic niche overlap suggest that common granivorous birds had a clear niche partitioning in southeastern Brazil in the late past,especially through foraging in distinct habitat types(forest and grassland;ISim=0.1,INes=0.2).Niche overlaps in almost all species-by-species comparisons were low(ISim≤0.3,INes≤0.4),except between C.brissonii and L.verreauxi(ISim=0.6,INes=1.0).These results suggest that these birds,belonging to the same trophic guild,coexisted through niche and resource partitioning.Despite being considered a plastic trophic guild,the isotopic niche partitioning among granivorous birds indicates that each of these species uses a set of specific resources and habitats.This raises an ecological concern about the homogenization of landscapes across the Neotropics,oversimplifying food resources and habitats to granivorous birds.

Additions of landscape metrics improve predictions of occurrence of species distribution models

Species distribution models are used to aid our understanding of the processes driving the spatial patterns of species’ habitats. This approach has received criticism, however, largely because it neglects landscape metrics. We examined the relative impacts of landscape predictors on the accuracy of habitat models by constructing distribution models at regional scales incorporating environmental variables (climate, topography, vegetation, and soil types) and secondary species occurrence data, and using them to predict the occurrence of 36 species in 15 forest fragments where we conducted rapid surveys. We then selected six landscape predictors at the landscape scale and ran general linear models of species presence/absence with either a single scale predictor (the probabilities of occurrence of the distribution models or landscape variables) or multiple scale predictors (distribution models + one landscape variable). Our results indicated that distribution models alone had poor predictive abilities but were improved when landscape predictors were added; the species responses were not, however, similar to the multiple scale predictors. Our study thus highlights the importance of considering landscape metrics to generate more accurate habitat suitability models.

The Effects of Host Diversity in Anthracnose Management and Race Composition of Colletotrichum sublineolum in Sorghum Lineage Mixtures

Alternative strategies of management of sorghum diseases were implemented using field experiments conducted in Embrapa Maize and Sorghum Research Center,Brazil in 2001 until 2003 to evaluate the efficacy of lineage mixtures of Sorghum bicolor for the control of anthracnose(caused by Colletotrichum sublineolum).The calculated values for disease severity considered the area under the disease progress curve(AUDPC)observed for the nine susceptible and resistant elite strains of sorghum planted in 30 stands randomly.Each stand was drawn in mixtures of three genotypes each,in the same proportions per plant.This design was compared with the severity of the disease measured in AUDPC calculated for each of the same nine strains of sorghum in pure stands.In most of the cases,the disease severity on the susceptible cultivars was decreased;and in some cases,reached 85%of disease reduction compared with disease progress in pure stand of correspondent plant.The implication and effect of these sorghum mixtures on the populations of C.sublineolum on each treatment were evaluated and revealed that there was an increase of frequency of complex races in most of these mixtures and a highest phenotypic diversity for virulence to pathogen populations from pure stands,than the characterized on populations collected from the mixtures,despite of the effectiveness on decrease of the anthracnose severity.

Effect of Larval Topical Application of Juvenile Hormone on Caste Determination in the Independent-Founding Eusocial Wasp <i>Mischocyttarus consimilis</i>(Hymenoptera: Vespidae)

Eusocial wasps are excellent models for understanding polyethism and division of labor among castes in social insects. However, little is known about the mechanisms controlling caste determination in eusocial wasps. Evidence suggests that the phenotype of queens in independent-founding (IF) eusocial wasps of the subfamily Polistinae can be partly fixed in the larval stage;however, this hypothesis has not yet been investigated. In this study we evaluate whether juvenile hormone (JH) affects pre-imaginal caste determination in the IF eusocial wasp Mischocyttarus consimilis (Hymenoptera: Vespidae). Analyzing morphometric and behavioral data, we demonstrated experimentally that females emerging from larvae that were treated with JH in the third instar had a significantly larger body size, spent more time in the nest, and were subject to less physical aggression from nestmates compared with females emerging from untreated control larvae. These results indicate that phenotype differences among castes in IF eusocial wasps can be partly fixed in the pre-adult stage and influenced by variations in the JH titer.

Artificial Night Lighting Reduces Firefly (Coleoptera: Lampyridae) Occurrence in Sorocaba, Brazil

Artificial night lighting is gaining attention as a new type of pollution;however, studies of its impacts are scarce. Fireflies provide good models to investigate its effects on nocturnal wildlife, since they depend on their bioluminescence for reproduction. This study investigated the impact of artificial illumination on firefly activity at the new campus of the Federal University of S&atildeo Carlos (Sorocaba, Brazil). The flashing activity of different firefly species, especially Photinus sp1 (82% of all occurrences), was investigated during 3 years, before and after the installation of multi metal vapor spotlights. Quantitative and qualitative analysis, performed in transects at different distances from the artificial light sources, showed significant negative effects on Photinus sp1 occurrence. This study proposes fireflies as potential flagship species and bioindicators for artificial night lighting and for the first time quantifies its effects, providing subsidies for future conservationist legislations regarding photopollution.

Chemical profile and antimicrobial activity of Secondatia floribunda A. DC(Apocynaceae)

Objective: To establish the chemical profile, and to evaluate the antibacterial and modulatory activity of the ethanolic extracts of the stalk's inner bark and heartwood of Secondatia floribunda.Methods: Quantification of total plienols and flavonoids was determined by the FolinCiocalteu method and aluminum chloride, respectively. Phenolic compounds were identified and quantified by HPLC-DAD(High Performance Liquid ChromatographyDiodearray Detector) and the Infrared Spectroscopy was performed using the measure by Attenuated Total Reflectance with Fourier Transform(ATR-FTIR). Antibacterial assays for determination of the Minimum Inhibitory Concentration(MIC) and modification of aminoglycosides were performed by microdilution.Results: Infrared spectra showed similar characteristics, having among its main absorption bands hydroxyl group(OH). The antibacterial activity showed clinically significant results for the strains of Staphylococcus aureus and Escherichia coli. In modulation assay, synergic and antagonistic effect for both extracts was observed.Hearttwood extract in combination with antibiotics showed a significant MIC reduction at 19.8%(P<0.0001)-79.3%(P<0.01).Conclusions: This study is the first report of chemical and biological information of Secondatia floribunda suggesting that it is clinically relevant source of a new antibacterial therapy, especially due to the presence of significant levels of phenolic compounds.

Vegetation structure and edaphic factors in veredas reflect different conservation status in these threatened areas

Background:In Cerrado humid areas,veredas are considered as hygrophilous communities,marked by the presence of the Mauritia flexuosa palm tree emerging in the wetter zones.Changes in veredas ecosystems due to drought and changes in the water table,which represent important areas for biodiversity maintenance in the Brazilian cerrado,can lead to the emergence of new landscapes and ecosystems.Assuming that the veredas are changed in species composition due to anthropogenic factors,in this study,we evaluated the flora composition and described the current vegetation profile of two veredas under different disturbances levels that are located in the north of Minas Gerais State,Brazil.Results:Altogether,2,268 individuals of 91 species belonging to 36 families were recorded.Our results demonstrated that the studied veredas were floristically different in terms of the arboreous-shrubby species composition,richness,and diversity.Despite the hygrophilous forest formations and open areas in the two veredas present typical species from these environments(same species with high importance values),the drought in the water table caused an expansion of Cerrado species in the open areas and in the hygrophilous forest.Furthermore,in the hygrophilous forest there was an increase in the abundance of species that occur in less saturated soils.Conclusion:Our results demonstrate that the studied veredas are changing in species composition due to anthropogenic factors which leads to the drought of these formations(water balance effect).These anthropogenic effects cause a modification with the expansion and increase in the abundance of typical species of other areas of Cerrado and resistant to less saturated soils,leading to the veredas collapse.Finally,future studies should investigate other veredas on a broader scale to detect changes in the water table that lead to a consequent change in vegetation structure.In this way,we will have support for the conscientious management and conservation of these areas that represent equilibrium places for the Cerrado biome.

Evaluation of antibiotic activity produced by Pseudomonas aeruginosa LV strain against Xanthomonas arboricola pv.pruni

Bacterial spot caused by Xanthomonas arboricola pv. pruni (Xap) is considered as a major problem in peach orchards. Copper and antibiotics are used to control, and biocontrol should be a new alternative with low environment impact. The objective was evaluated by the antibiotic activity of the metabolite produced by Pseudomonas aeruginosa LV strain. The free cells supernatant was fractionated with a serial organic solvent with crescent polarity and a dichloromethane phase was concentrated and lyophilised, and after was fractionated using vacuum liquid chromatography. The antibiotic activity of the F3 fraction containing an organometallic compound was tested on Xap in vitro and in a greenhouse conditions. Plants were sprayed with F3 before or after Xap infection and the results showed changes in exopolysaccharides and cell morphology. The F3 concentration of 450 μg·mL-1 was more effective. The results showed that F3 fraction could be a new alternative to control bacterial spot.

Determinant variables on the isotopic values of particulate organic matter in a neotropical floodplain

Particulate organic matter(POM)is an important energy source for aquatic consumers,understanding its origin and composition is essential for understanding the energetic dynamics of aquatic environments.The aim of this study was to analyze the relationship between POM and phytoplankton(isotopic values and chlorophyll concentration)and abiotic variables during dry and rainy seasons.Sampling was conducted in rivers and lagoons in the floodplain of the Upper ParanáRiver.We found a greater difference in ^(δ13)C values of POM between sampling points than between seasons,indicating that the composition of regional sources influences the composition of POM more than dry and rainy seasons.In addition,the concentration of chlorophyll during the dry season was positively correlated with ^(δ13)C values during that rainy period.Additionally,we found a relationship between factors limiting the growth of phytoplankton and ^(δ13)C values of POM,such as phosphate ions,indicating that variables that regulate phytoplankton growth tend to influence the composition of POM in river floodplains.Therefore,maintaining the variables that regulate the phytoplankton community is of fundamental importance for the composition of POM,an important energy source in aquatic environments.

Biodiversity responses to insular fragmentation in Amazonia: Two decades of research in the Balbina Hydroelectric Reservoir

As hydropower development expands across lowland tropical forests,flooding and concomitant insular fragmentation have become important threats to biodiversity.Newly created insular landscapes serve as natural laboratories to investigate biodiversity responses to fragmentation.One of these most iconic landscapes is the Balbina Hydroelectric Reservoir in Brazilian Amazonia,occupying>400000 ha and comprising>3500 forest islands.Here,we synthesise the current knowledge on responses of a wide range of biological groups to insular fragmentation at Balbina.Sampling has largely concentrated on a set of 22 islands and three mainland sites.In total,39 studies were conducted over nearly two decades,covering 17 vertebrate,invertebrate,and plant taxa.Although species responses varied according to taxonomic group,island area was consistently included and played a pivotal role in 66.7%of all studies examining patterns of species diversity.Species persistence was further affected by species traits,mostly related to species capacity to use/traverse the aquatic matrix or tolerate habitat degradation,as noted for species of vertebrates and orchid bees.Further research is needed to improve our understanding of such effects on wider ecosystem functioning.Environmental Impact Assessments must account for changes in both the remaining habitat amount and configuration,and subsequent long-term species losses.

生物多样性热点地区内的群落预测:堆叠物种分布模型与森林清查数据对比

鉴于当前气候变化和人类活动的影响,生物多样性的空间预测对其保护和修复至关重要。本文将不同堆叠物种分布模型(stacked species distribution models,S-SDMs)的预测结果与森林清查数据进行了比较,以评估这些S-SDMs模型能否捕获生物多样性热点地区物种丰富度的新特性和地理分布及局部群落的组成。我们选取大西洋沿岸森林151处地点的1499个树种进行SDM模型构建,并利用4种模型堆叠方法重建植物群落。这43种方法分别为二进制SDM模型(bS-SDM)、由最小凸多边形裁剪得到的二进制SDM模型(bS-SDM-CROP)、受物种丰富度观测结果约束的堆叠SDM模型(cS-SDM)以及物种出现点的最小凸多边形(MCP)。我们从物种丰富度、组成、群落预测指标以及β多样性组分(物种嵌套和物种周转)等方面将各堆叠方法与局部群落进行对比。研究结果表明,所有S-SDM模型均捕获到了一般分布格局,其中bS-SDM-CROP模型最为简约。各堆叠模型预测得到的物种组成与局部群落的实际情况存在一定的差异,其中bS-SDM、bS-SDM-CROP和MCP模型呈现出嵌套格局,而物种周转在cS-SDM模型中最为显著。这些S-SDM模型在性能、遗漏率和记账错率方面的表现各不相同,对一些脆弱、濒危和极度濒危物种给出了错误预测。尽管与森林清查数据有差别,但这些S-SDM模型均捕获了与局部群落数据的部分差异,可以表征物种的潜在分布区。本研究的结论有助于S-SDM模型在粗尺度生物多样性整合与保护规划中的应用,但在生物高度多样性地区局部尺度上可能会得出错误的预测结果。

What a few hairs can tell us about the resource use of giant armadillos

Understanding of resource requirements of vulnerable species is key for conservation planning.Here,we used sta-ble carbon(δ13C)and nitrogen isotopes(δ15N)of hair from giant armadillos(Priodontes maximus)to understand individual resource use.We collected hair from 19 giant armadillos analyzing 34 samples from the Brazilian Pan-tanal and compared the resource use between sexes and age classes.We also assessed the relationship of isotopic values with individuals’body mass and the habitat type used.We observed a wide variation in resource use by giant armadillos,showing that individuals consume prey that feeds on distinct resources and occupies different habitat types,indicating that there is individual variation in foraging behavior.Most giant armadillos presented a mixed diet(C3/C4 resources,forests/open areas),but a quarter of individuals had strictly C4 diets(open areas).Males are more prone to forage on C4 resources,presenting an isotopic niche 2.6-times larger than that of females.Subadults presented diets more associated with habitats with high arboreal cover(C3 resources,forests),while adults foraged more in open areas(C4 resources).This result is mirrored by the positive relationship betweenδ13C values and body mass,suggesting that larger giant armadillos tend to feed more in open areas.We observed thatδ13C values decreased as individuals increased the use of habitats with high arboreal cover.We stress the importance of con-serving the natural mosaic in the Pantanal landscape for the species persistence,given that giant armadillos require all habitat types to fulfill their dietary,spatial,and developmental needs.

The influence of soil on vegetation structure and plant diversity in different tropical savannic and forest habitats

Aims Soil plays an important role in the formation and heterogene-ity of habitats and thus can cause changes in vegetation struc-ture and plant diversity.The differentiation between Cerrado/savanna and forest is well known,but the relationship between soil and habitats from savannic or forest formations still needs to be better understood,particularly in tropical ecotonal areas.We studied the association between attributes of plant com-munities,namely structure and diversity,and physicochemical characteristics of soils in the Caatinga domain at the transition to Cerrado in Brazil.Methods Chemical and physical analyses of soils were performed in samples of 38 plots from savannic formations and 30 plots from forest forma-tions.Vegetation was characterized floristically and structurally in all plots,five habitats being assessed in each plant formation.Soil features and vegetation parameters were highly distinct among the different habitats.Important Findingsin general,forest habitats were more nutrient rich than savannic formation.Furthermore,soil variables showed effects both on vegetation structure and on its species diversity,more pronouncedly in the savannic formations.Habitats were structurally distinct,and diversity differed between savannic and forest communities;however,a higher differentiation occurred when the savannic formation habitats were compared among them.Although plant diversity did not differ among forest formation habitats,soil attributes showed a close relationship with edaphic factors and can contribute for similar vegetation.The soil-vegetation relationship in highly diverse ecotonal landscapes is important from the conservation biology point of view and aid in the execution of proactive plans for the maintenance of biodiversity.Thus,we noticed that diversity and soil behaves distinctly between savannic and forest communities.

Soil and altitude drive diversity and functioning of Brazilian Páramos(campo de altitude)

Aims the vegetation on Brazilian Páramos consists of assemblages that are driven mainly by the influence of strong environmental filtering.It is very important to understand the effect of environmental varia-tion on taxonomic diversity and on functional diversity.considering the lack of information about the functional diversity in Brazilian Páramos,we analyzed for the first time the effects of altitude and edaphic attributes on functional traits,as well as on taxonomic and functional diversity.We also wanted to answer the questions:Which ecological strategies are favorable in high-altitude grassland?Does soil attributes determine distributions of traits in high-altitude grassland?considering the studied altitudinal gradient is altitude an important variable in the community assembly?Methods the study was conducted on three mountains:Mammoth(1850 m),Elephant(1790 m)and totem(1690 m)in Serra do Brigadeiro State Park,Minas Gerais State,Brazil.those mountains represent the‘Serra das cabeças’,a smaller ridge that is surrounded by the Atlantic Forest,one of the 25 hotspot of biodiversity.the samples were taken using 100 plots of 1 m2 per mountain that were randomly distributed.All plants except mosses were sampled.the taxonomic diversity was evaluated using richness,Shannon diversity,effective number of species and Pielou evenness.For the functional diver-sity,we considered the functional richness,functional evenness and functional divergence.Generalized linear models(GLM/Poisson and quasi-Poisson)were used to evaluate the effect of abiotic variables(altitude,soil depth and soil chemical attributes)on biotic variables(number of species and individuals,life form,dispersal and fruit type)and ordinary least squares regression to evaluate the effect of abiotic variables on the functional and taxonomic diversity.Important Findingsthe soil variables presented a considerable edaphic gradient associated with altitude.the soil in Serra das cabeças plays an important role for the plant diversity:richness and diversity index were positively related with fertility.With regard to the life form,nanophanerophytes tended to increase with altitude and soil depth,while therophytes tended to decrease with altitude.the dispersal type was also associated with the abiotic variables:autochory decreases with altitude,while zoochory increases.Functional richness increases with fertility and the functional evenness with altitude.the studied gradient showed that altitude is working as a filter for functional traits and indices and is,together with soil attributes,an important determinant for the distribution of plants on Brazilian Páramos.

Can morphological and behavioral traits predict the foraging and feeding dynamics of social arachnids?

Complex social insect species exhibit task specialization mediated by morphological and behavior-al traits.However,evidence of such traits is scarce for other social arthropods.We investigated whether the social pseudoscorpion Paratemnoides nidificator exhibits morphologically and behav-iorally specialized individuals in prey capture.We measured body and chela sizes of adult pseudo-scorpions and analyzed predation processes.Larger individuals spent more time moving through the colony and foraging than smaller pseudoscorpions.Individuals that captured prey had increased body and absolute chelae sizes.Although larger individuals had relatively small chelae size,they showed a higher probability of prey capture.Larger individuals manipulated prey often,although they fed less than smaller pseudoscorpions.Individuals that initiated captures fed more frequently and for more time than the others.Natural selection might be favoring individuals speci-alized in foraging and colony protection,allowing smaller and less efficient adults to avoid contact with dangerous prey.To our knowledge,there is incipient information regarding specialized indi-viduals in arachnids,and our results might indicate the emergence of a morphologically special-ized group in this species.

Acromyrmex ameliae sp. n. （Hymenoptera： Formicidae）： A new social parasite of leaf-cutting ants in Brazil

The fungus-growing ants （Tribe Attini） are a New World group of〉 200 species, all obligate symbionts with a fungus they use for food. Four attine taxa are known to be social parasites of other attines. Acromyrmex （ Pseudoatta） argentina argentina and Acromyrmex （Pseudoatta） argentina platensis （parasites of Acromyrmex lundi）, and Acromyrmex sp. （a parasite of Acromyrmex rugosus） produce no worker caste. In contrast, the recently discovered Acromyrmex insinuator （a parasite of Acromyrmex echinatior） does produce workers. Here, we describe a new species, Acromyrmex ameliae, a social parasite of Acromyrmex subterraneus subterraneus and Acromyrmex subterraneus brunneus in Minas Gerais, Brasil. Like A. insinuator, it produces workers and appears to be closely related to its hosts. Similar social parasites may be fairly common in the fungus-growing ants, but overlooked due to the close resemblance between parasite and host workers.

Tree phenology along a successional gradient of tropical Atlantic Forest

Aims Changes in habitat characteristics and species composition in suc-cessional gradients could determine temporal variation in phenol-ogy of second-growth forests.We evaluated phenological patterns in tree species occurring in successional forests in southern Brazil,aiming to assess community changes along succession.We tested for general patterns and phenophase seasonality of trees of forests in successional stages and for differences in occurrence,concentra-tion,frequency and duration of phenophases.Methods Vegetative(flushing and leaf-fall)and reproductive(flowering and fruiting)phenophases of 149 individuals of 29 tree species were monitored monthly,for 2 years,in a successional gradient:early-(~10 years),mid-(~30 years)and late-successional(>80 years)forests in southern Brazil.Important Findings Forests in the successional gradient exhibited shared frequency and duration of phenological phases,probably due to climatic or historical constraints in phenology.However,we found differences in the rate of occurrence and concentration of phenological phases,suggesting that habitat changes caused by succession and species turnover are additional factors affecting phenological patterns in tropical forests.

Effects of the availability of floral resources and neighboring plants on nectar robbery in a specialized pollination system

Many plants pollinated by nectar-foraging animals have to maintain a balance between legitimate visitor attraction strategies and mechanisms that minimize illegitimate visits.This study investigated how floral display and neighboring species composition influences nectar robbing by hummingbirds in the tropical ornithophilous herb Heliconia spathocircinata.We tested the role of inflorescence display,flower abundance,and neighboring species in the reduction of nectar robbing in H.spathocircinata.Our results indicate that nectar robbing hummingbird activity was higher in moderately large inflorescence displays and that the frequency of nectar robbing in H.spathocircinata decreases with increased flower abundance and the presence of neighboring plant species.Neighboring non-ornithophilous plants decreased the frequency of nectar robbing in H.spathocircinata flowers to a greater extent than ornithophilous ones.These results suggest that nectar robbing hummingbirds are attracted to similar conditions that attract legitimate visitors and that spatial aggregation and mixed-species displays may represent a mechanism to dilute nectar robbing effects at an individual level.