scholarly journals Cheaters in mutualism networks

2010 ◽  
Vol 6 (4) ◽  
pp. 494-497 ◽  
Author(s):  
Julieta Genini ◽  
L. Patrícia C. Morellato ◽  
Paulo R. Guimarães ◽  
Jens M. Olesen
Keyword(s):  
Network Topology ◽  
Strong Impact ◽  
Network Organization ◽  
Flower Visitors ◽  
Interacting Species ◽  
Flower Visitation ◽  
Different Types ◽  
Network Studies ◽  
Effective Pollinators

Mutualism-network studies assume that all interacting species are mutualistic partners and consider that all links are of one kind. However, the influence of different types of links, such as cheating links, on network organization remains unexplored. We studied two flower-visitation networks (Malpighiaceae and Bignoniaceae and their flower visitors), and divide the types of link into cheaters (i.e. robbers and thieves of flower rewards) and effective pollinators. We investigated if there were topological differences among networks with and without cheaters, especially with respect to nestedness and modularity. The Malpighiaceae network was nested, but not modular, and it was dominated by pollinators and had much fewer cheater species than Bignoniaceae network (28% versus 75%). The Bignoniaceae network was mainly a plant–cheater network, being modular because of the presence of pollen robbers and showing no nestedness. In the Malpighiaceae network, removal of cheaters had no major consequences for topology. In contrast, removal of cheaters broke down the modularity of the Bignoniaceae network. As cheaters are ubiquitous in all mutualisms, the results presented here show that they have a strong impact upon network topology.

scholarly journals The floriphilic katydid, Phaneroptera brevis, is a frequent flower visitor of non-native, flowering forbs

2019 ◽  
Vol 28 (2) ◽  
pp. 21-26
Author(s):  
Ming Kai Tan ◽  
Hui Lee ◽  
Hugh Tiang Wah Tan
Keyword(s):  
Model Organism ◽  
Environmental Parameters ◽  
Plant Species Richness ◽  
Limited Information ◽  
Pollination Services ◽  
Resource Concentration ◽  
Flower Visitors ◽  
Resource Concentration Hypothesis ◽  
Flower Visitation ◽  
Flower Visiting

Distribution of consumers in a patch of vegetation can be predicted by resource availability and explained by the resource-concentration and optimal-foraging hypotheses. These hypotheses have not been explored for flower-visiting Orthoptera because they are deemed less economically or ecologically important. Some flower-visiting orthopterans can provide pollination services, which warrants more attention. We studied a Singaporean, floriphilic katydid, Phaneropterabrevis, to investigate the following questions: 1) how frequently does P.brevis visit flowers compared to other flower visitors and 2) what factors predict the abundance of P.brevis? We collected abundance data for P.brevis and other flower-visiting arthropods and quantified seven environmental parameters, including flower abundance and host-plant species richness. We found that P.brevis frequents flowers significantly more often than some common and expected flower visitors such as hoverflies. In line with the prediction of the resource-concentration hypothesis, the abundance of P.brevis was positively correlated with a higher flower abundance. Owing to the limited information on unexpected wild flower visitors and pollinators, especially from the understudied tropics of Southeast Asia, we propose that P.brevis can be a model organism for future studies to answer fundamental questions on flower visitation.

Experimental study on anti-collision device using titanium steel and recycle tires

2021 ◽  
Author(s):  
Ziheng Xin ◽  
Haiying Ma ◽  
Junjie Wang ◽  
Hao Gao ◽  
Yanchen Song
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Test Specimen ◽  
Impact Load ◽  
Finite Element Models ◽  
Strong Impact ◽  
New Device ◽  
Different Types ◽  
Scale Test ◽  
Ship Collision

<p><br clear="none"/></p><p>Anti-collision devices can reduce the damage of bridge columns under ship collision, and a new device is proposed in the paper using a combination of titanium steel and recycle tires. The proposed device effectively improves the performance of buffering energy dissipation and durability under strong impact load. A 0.6 scale test specimen was designed and tested to investigate the behavior of the device under impact load; finite element models were conducted to analyze and compare with the experimental results. The performances of different types of the anti-collision device are compared, and the failure mechanism is studied.</p>

Types of Flower Visitors: Syndromes, Constancy, and Effectiveness

2011 ◽  
Author(s):  
Pat Willmer
Keyword(s):  
Adaptive Radiation ◽  
Convergent Evolution ◽  
Pollination Syndromes ◽  
Pollinator Effectiveness ◽  
Flower Constancy ◽  
Flower Visitors ◽  
Floral Constancy ◽  
Effective Pollinators

This chapter examines pollination syndromes, floral constancy, and pollinator effectiveness. Flowers show enormous adaptive radiation, but the same kind of flower reappears by convergent evolution in many different families. Thus many families produce rather similar, simple bowl-shaped flowers like buttercups; many produce similar zygomorphic tubular lipped flowers; and many produce fluffy flower heads of massed (often white) florets. These broad flower types are the basis of the idea of pollination syndromes—the flowers have converged on certain morphologies and reward patterns because they are exploiting the abilities and preferences of particular kinds of visitor. After providing an overview of pollination syndromes, the chapter explains why pollination syndromes can be defended. It then considers flower constancy, along with the distinction between flower visitors and effective pollinators. It concludes with some observations on how flower visitors can contribute to speciation of plants through specialization and through their constancy.

scholarly journals Effect of dust deposition on the performance of photovoltaic modules in Taxila, Pakistan

2017 ◽  
Vol 21 (2) ◽  
pp. 915-923 ◽  
Author(s):  
Hafiz Ali ◽  
Muhammad Zafar ◽  
Muhammad Bashir ◽  
Muhammad Nasir ◽  
Muzaffar Ali ◽  
...  
Keyword(s):  
Output Power ◽  
Photovoltaic Module ◽  
Strong Impact ◽  
Dust Deposition ◽  
Average Output ◽  
Photovoltaic Modules ◽  
Time Period ◽  
Different Types ◽  
The Difference ◽  
Module Efficiency

The air borne dust deposited on the surface of photovoltaic module influence the transmittance of solar radiations from the photovoltaic modules glazing surface. This experimental work aimed to investigate the effect of dust deposited on the surface of two different types of photovoltaic modules (monocrystalline silicon and polycrystalline silicon). Two modules of each type were used and one module from each pair was left exposed to natural atmosphere for three months of winter in Taxila, Pakistan. Systematic series of measurements were conducted for the time period of three months corresponding to the different dust densities. The difference between the output parameters of clean and dirty modules provided the information of percentage loss at different dust densities. The dust density deposited on the modules surface was 0.9867 mg/cm2 at the end of the study. The results showed that dust deposition has strong impact on the performance of photovoltaic modules. The monocrystalline and polycrystalline modules showed about 20% and 16% decrease of average output power, respectively, compared to the clean modules of same type. It was found that the reduction of module efficiency (?clean ? ?dirtv) in case of monocrystalline and polycrystalline module was 3.55% and 3.01%, respectively. Moreover the loss of output power and module efficiency in monocrystalline module was more compared to the polycrystalline module.

The causes of extinction

1989 ◽  
Vol 325 (1228) ◽  
pp. 241-252 ◽  
Keyword(s):  
Fossil Record ◽  
Species Turnover ◽  
Rapid Evolution ◽  
Taxonomic Diversity ◽  
Species Selection ◽  
Biotic Factors ◽  
Taxonomic Distribution ◽  
Interacting Species ◽  
Fossil Evidence ◽  
Different Types

A species may go extinct either because it is unable to evolve rapidly enough to meet changing circumstances, or because its niche disappears and no capacity for rapid evolution could have saved it. Although recent extinctions can usually be interpreted as resulting from niche disappearance, the taxonomic distribution of parthenogens suggests that inability to evolve may also be important. A second distinction is between physical and biotic causes of extinction. Fossil evidence for constant taxonomic diversity, combined with species turnover, implies that biotic factors have been important. A similar conclusion emerges from studies of recent introductions of predators, competitors and parasites into new areas. The term ‘species selection’ should be confined to cases in which the outcome of selection is determined by properties of the population as a whole, rather than of individuals. The process has been of only trivial importance in producing complex adaptations, but of major importance in determining the distribution of different types of organisms. An adequate interpretation of the fossil record requires a theory of the coevolution of many interacting species. Such a theory is at present lacking, but various approaches to it are discussed.

scholarly journals Um olhar comparativo sobre a regulamentação dos veículos de mídia exterior urbana: os casos de São Paulo (cidade) e Roma | A comparative view of urban outdoor advertising (Out-Of-Home media) regulation: the cases of São Paulo (city) and Rome

2018 ◽  
Vol 15 (1) ◽  
pp. 17-44
Author(s):  
Vanessa Casarin ◽  
Raquel Martinelli
Keyword(s):  
Urban Landscape ◽  
Sao Paulo ◽  
Strong Impact ◽  
São Paulo ◽  
Outdoor Advertising ◽  
Aesthetic Quality ◽  
Media Regulation ◽  
Different Types ◽  
The Aesthetic ◽  
The City

O objetivo central deste trabalho é apresentar um estudo comparativo sobre como as cidade de São Paulo e Roma tem lidado em suas regulamentações com os diferentes suportes de mídia exterior urbana, uma vez que são estas normas que moldam com maior ou menor rigor a forma com que a informação de caráter comercial chega aos cidadãos. O desenho da informação depende, fundamentalmente, do suporte através do qual será veiculada.  A mídia exterior tem um forte impacto na paisagem urbana e a partir da Lei Cidade Limpa implantada em São Paulo diversas cidades brasileiras se viram incentivadas a implantar ou alterar suas normativas neste sentido. A fim de contribuir com este fenômeno, procurou-se então estabelecer um paralelo entre a cidade de São Paulo, uma cidade de negócios, e a cidade de Roma, fortemente orientada ao turismo incentivado pelo seu profícuo patrimônio histórico, principalmente arquitetônico. No caso de São Paulo abordou-se o contexto de aplicação da regulamentação específica mais recente e suas alterações posteriores. Fez-se, a partir de uma analise documental da legislação vigente, uma comparação com a cidade de Roma. Observou-se que embora a cidade de Roma seja fortemente orientada ao turismo e a exploração da qualidade estética de sua paisagem, é mais permissiva em relação a presença de diferentes suportes de mídia exterior na paisagem urbana do que a cidade de São Paulo.*****The main aim of this paper is to present a comparative study between the cities of São Paulo and Rome, and how these cities are dealing with different types of urban outdoor advertising (Out-Of-Home media) in its regulations since these regulations shape the way commercial information is placed in the landscape. The information design depends, mainly, on the support it will be placed. Outdoor advertising has a strong impact on the urban landscape. Since the Clean City Law was implanted in São Paulo, several Brazilian cities have been encouraged to implement (or modify) regulations in this sense. In order to contribute to this discussion, a parallel between the city of São Paulo, a business city, and the city of Rome, strongly oriented to the tourism encouraged by its historical heritage, mainly architectonic, are presented in this paper. The results shown consider only the documental analysis (of the normative legislation, maps, and publications pertinent to the subject) which formed the basis for the evaluation of the landscape, and not the evaluation of the landscape itself. It refers to the initial stage of the research. Its character is, therefore, descriptive and the comparison established between the different case studies aims to foment the discussion around the paths followed by the cities to deal with the spread and diversity of the OOH media nowadays. It was observed that although the city of Rome is mainly oriented to tourism and the profiteering of the aesthetic quality of its landscape, it is more permissive in relation to the presence of different types of OOH media in the urban landscape than the city of São Paulo.

The topology of a plant-insect visitation network from the Hajar Mountains, Oman

2021 ◽  
Vol 72 (1) ◽  
pp. 39-55
Author(s):  
J. Monks
Keyword(s):  
Network Topology ◽  
Arabian Peninsula ◽  
Plant Insect Interactions ◽  
Flower Visitation ◽  
Lepidopteran Species ◽  
Insect Visitation ◽  
Bee Diversity ◽  
Socotra Archipelago ◽  
Insect Interactions ◽  
First Time

The Arabian Peninsula is a hotspot for bee diversity but studies looking at plant-insect interactions there remain rare. A network analysis of insects visiting wildflowers in the Hajar Mountains, Oman was made from the results of eight survey periods between 2016 and 2020. Centrality scores were used to assess the role different groups of potential pollinators play in network topology. A list of 113 insect species visiting 26 plant species has been compiled with Lepidopteran species acting as important connectors within the network. A nested, asymmetric and compartmentalised network was recorded. The order Hymenoptera was the most species rich group, with 46 species recorded followed by Diptera (43 spp.), Lepidoptera (13 spp.), and Coleoptera (11 spp.). Amegilla pyramidalis (Kirby, 1900) (Hymenoptera: Apidae: Antho phorini) is recorded for the first time outside of the Socotra Archipelago. The study is the first specific effort to record the flower visitation behaviour of insects in Oman and gives an overview of the resulting visitation network.

scholarly journals A Study on the Relationship between Connecting Different Types of Nodes and Disassortativity by Degree

2010 ◽  
Vol 2010 ◽  
pp. 1-13
Author(s):  
Chengdong Dong
Keyword(s):  
Network Topology ◽  
The Other ◽  
Analytical Results ◽  
Different Types ◽  
The Relationship

This paper investigates how to change the disassortativity of the whole network by connecting nodes of different types in two communities. A model connecting two multi-center networks is studied to see if analytical results are achievable. There are three main methods to connect two multi-center subnetworks depending on whether the connecting nodes are centers: (1) connect the centers of one sub-network to noncenter nodes of the other sub-network, (2) connect the centers of the two sub-networks together, and (3) connect non-center nodes of the two sub-networks. The results show that the disassortative property of a single multicenter network can be maintained in scenarios (1) and (2) above, but the disassortativity is changed in (3). In conclusion, either assortativity or disassortativity is achievable by connecting nodes with different degree properties in an ideal network constructed from two communities with similar network topology.

scholarly journals How Do Budget Level and Type of Incentives Influence Performance?

2019 ◽  
Author(s):  
Caesar Marga Putri ◽  
Indah Wirantika Susanti
Keyword(s):  
Task Complexity ◽  
Individual Performance ◽  
Incentive Contracts ◽  
Strong Impact ◽  
Complex Tasks ◽  
Social Incentives ◽  
Different Types ◽  
Budget Levels

This research experimentally compares the influence of budget-based contracts and social incentives on individual performance. This paper compares two different types of budget-based contracts, budget-linear and budget-fixed, along with social incentives on individual performance. Assigning individuals in different budget levels, 75% or 100%, to perform complex tasks will lead to different performance outputs. The results show that individual performance will be higher when they receive a budget-linear contract. Social incentives have a strong impact on both types of budget-based contracts. The result of the study on the influence of budget levels confirms previous research that higher budget levels will led to higher performance when compared with lower budget levels. Keywords: Budget-based incentive contracts, social incentives, budget level, task complexity, individual performance.

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