The Experts below are selected from a list of 56352 Experts worldwide ranked by ideXlab platform
Eduard K Linsenmair - One of the best experts on this subject based on the ideXlab platform.
-
measurement of parental Investment and sex allocation in the european beewolf philanthus triangulum f hymenoptera sphecidae
1999Co-Authors: Erhard Strohm, Eduard K LinsenmairAbstract:Fisher’s 1930 theory of sex allocation predicts a population-wide 1:1 Ratio of parental Investment. We tested this prediction in the European beewolf, a sphecid wasp that hunts for honeybees as larval food. Because the method to quantify parental Investment is of crucial importance, we compared the suitability of several different Investment measures. Female/male cost Ratios were determined from a sample and the total Investment in sons and daughters was calculated. In addition, the actual number of prey items for sons and daughters was directly determined by excavating nests and counting the cuticle remains of the prey. Though mortality was high (70%), it had only a weak effect on the estimate of the Investment Ratio. Based on commonly used measures like fresh and dry weight of emerged adults, the Investment Ratio did not deviate from Fisher’s prediction of equal Investment. However, progeny weight considerably underestimates Investment in males and Investment in large progeny. Measures that reflect the allocation of resources more directly (amount of provisions, brood cell volume) revealed a significant male bias and thus contradicted Fisher’s theory. Three kinds of explanation are discussed. First, non-adaptive explanations are unlikely. Second, from the spectrum of alternative adaptive theories, only models that assume a non-linear relationship between amount of Investment and progeny fitness seem to be relevant for the study species. Third, though the number of prey in a brood cell seems to be a rather good measure of parental Investment in European beewolves, some problems in measuring parental Investment remain. These problems are of broad significance.
-
low resource availability causes extremely male biased Investment Ratios in the european beewolf philanthus triangulum f hymenoptera sphecidae
1997Co-Authors: Erhard Strohm, Eduard K LinsenmairAbstract:Conditional sex allocation theory predicts that under poor conditions parents should produce more of the cheaper sex. Alternatively, females could provide less food for the single progeny or store resources (and thus decrease their rate of reproduction) when food is scarce. These non exclusive options were experimentally tested in the European beewolf where females provision brood cells with paralysed honey bees. Depending on the severity of the food restriction (number of available prey bees per day) females made use of one or more of the different options. In accordance with conditional sex allocation theory the Investment Ratio was biased towards the cheaper sex (sons) under poor conditions. Females also decreased the amount of food per progeny at very low food availability and stored food under one condition.
Erhard Strohm - One of the best experts on this subject based on the ideXlab platform.
-
measurement of parental Investment and sex allocation in the european beewolf philanthus triangulum f hymenoptera sphecidae
1999Co-Authors: Erhard Strohm, Eduard K LinsenmairAbstract:Fisher’s 1930 theory of sex allocation predicts a population-wide 1:1 Ratio of parental Investment. We tested this prediction in the European beewolf, a sphecid wasp that hunts for honeybees as larval food. Because the method to quantify parental Investment is of crucial importance, we compared the suitability of several different Investment measures. Female/male cost Ratios were determined from a sample and the total Investment in sons and daughters was calculated. In addition, the actual number of prey items for sons and daughters was directly determined by excavating nests and counting the cuticle remains of the prey. Though mortality was high (70%), it had only a weak effect on the estimate of the Investment Ratio. Based on commonly used measures like fresh and dry weight of emerged adults, the Investment Ratio did not deviate from Fisher’s prediction of equal Investment. However, progeny weight considerably underestimates Investment in males and Investment in large progeny. Measures that reflect the allocation of resources more directly (amount of provisions, brood cell volume) revealed a significant male bias and thus contradicted Fisher’s theory. Three kinds of explanation are discussed. First, non-adaptive explanations are unlikely. Second, from the spectrum of alternative adaptive theories, only models that assume a non-linear relationship between amount of Investment and progeny fitness seem to be relevant for the study species. Third, though the number of prey in a brood cell seems to be a rather good measure of parental Investment in European beewolves, some problems in measuring parental Investment remain. These problems are of broad significance.
-
temperature dependence of provisioning behaviour and Investment allocation in the european beewolf philanthus triangulum f
1998Co-Authors: Erhard Strohm, K. Eduard LinsenmairAbstract:1. Fisher's sex allocation theory predicts equal Investment in sons and daughters. However, in a central European population of the beewolf Philanthus triangulum F. (Hymenoptera: Sphecidae), the sex Ratio of parental Investment is heavily biased towards males. 2. Beewolf females hunt for honeybees and carry them to the nest in flight. In order to fly with the additional load, females must have a certain minimum size that can be attained only with at least three bees as larval food. In contrast, sons require only one bee. Storage of bees might be constrained by an increasing risk of parasitism and fungus infestation. Therefore the female needs to gather the necessary bees to produce a daughter within a short period of time. Under bad weather conditions, females might too often not be able to accomplish this and might be compelled to produce an excess of less costly sons. This hypothesis was tested by investigating the temperature dependence of the hunting and provisioning behaviour of beewolf females. 3. Under semi-field and field conditions, the duRation of the daily activity period and the number of bees a female brought to the nest correlated positively with two measures of ambient temperature, maximum air temperature, and temperature sum during the activity period. The duRation of hunting trips but not the duRation of pauses between hunting trips correlated negatively with temperature. An estimate of the Investment Ratio was not significantly correlated with ambient temperature. The proportion of the variance in Investment Ratio that was explained by ambient temperature was less than 10%. 4. In the laboratory, temperatures affected hunting success but females did not produce more daughters at higher temperatures. 5. In a subtropical climate in southern France, the population Investment Ratio was biased towards males to the same extent as in central Europe. 6. Thus, temperature affects several aspects of hunting behaviour, but low temperatures do not lead to an overproduction of male offspring and thus are not a constraint that could explain the observed male-biased Investment Ratio.
-
low resource availability causes extremely male biased Investment Ratios in the european beewolf philanthus triangulum f hymenoptera sphecidae
1997Co-Authors: Erhard Strohm, Eduard K LinsenmairAbstract:Conditional sex allocation theory predicts that under poor conditions parents should produce more of the cheaper sex. Alternatively, females could provide less food for the single progeny or store resources (and thus decrease their rate of reproduction) when food is scarce. These non exclusive options were experimentally tested in the European beewolf where females provision brood cells with paralysed honey bees. Depending on the severity of the food restriction (number of available prey bees per day) females made use of one or more of the different options. In accordance with conditional sex allocation theory the Investment Ratio was biased towards the cheaper sex (sons) under poor conditions. Females also decreased the amount of food per progeny at very low food availability and stored food under one condition.
Laurent Keller - One of the best experts on this subject based on the ideXlab platform.
-
role of resource availability on sex caste and reproductive allocation Ratios in the argentine ant linepithema humile
2001Co-Authors: Serge Aron, Laurent Keller, Luc PasseraAbstract:Summary 1 Resource availability has long been recognized to influence reproductive decisions in eusocial Hymenoptera. We analysed how protein availability affects the number and the weight of worker, male and queen pupae, as well as its effect on sex, caste and reproductive allocation Ratios, in the Argentine ant Linepithema humile Mayr. Colonies were maintained on diets with three levels of access to proteins: no protein, intermediate and high levels of proteins. 2 There was no significant difference between the intermediate and high levels of protein in the number of queen, male and worker pupae produced. Similarly, the intermediate vs. high levels of protein treatments did not differ with regard to the weight of pupae nor the relative Investments between the three castes. This suggests that, in L. humile, there could be a threshold over which additional amounts of protein have no more effect on reproductive allocation or the size of the individuals produced. 3 The main effect of protein supplementation was to increase the number of sexual pupae (queens and males) produced. By contrast, the number of workers produced remained unaffected by the level of proteins. The higher Investment in sexuals in nests supplemented with proteins resulted in a significantly higher proportion of queen pupae among females, as well as higher proportion of males among all individuals produced in these nests. However, the proportion of males among sexuals (numerical sex Ratio) was not significantly different between supplemented and unsupplemented nests. 4 Workers reacted to a higher protein diet not only by rearing more sexuals, but also by producing larger individuals of the three castes. 5 The proportional Investment allocated to queens among females was higher in the protein-supplemented treatments. Protein-supplemented nests also invested proportionally more into sexual production than unsupplemented nests. However, whereas increased sexual production is generally associated with a more female-biased sex Investment Ratio in ants, sex allocation Ratio was not significantly different between supplemented and unsupplemented nests. 6 Overall, our results support the view that protein availability influences the proportion of brood that is culled, with workers eliminating a significant proportion of both the male and female sexual brood in unsupplemented nests. 7 The increasing amount of experimental data showing that brood culling is an important part of the biology of ants and other social insects emphasis the need to combine kin selection and life-history approaches to study the outcome of queen–worker conflicts on the dynamics of colony growth and sex allocation.
-
colony sex Ratios vary with queen number but not relatedness asymmetry in the ant formica exsecta
2000Co-Authors: William D. Brown, Laurent KellerAbstract:Split-sex-Ratio theory assumes that conflict over whether to produce predominately males or female reproductives (gynes) is won by the workers in haplodiploid insect societies and the outcome is determined by colony kin structure. Tests of the theory have the potential to provide support for kin-selection theory and evidence of social conflict. We use natural variation in kinship among polygynous (multiple-queen) colonies of the ant Formica exsecta to study the associations between sex Ratios and the relatedness of workers to female versus male brood (relatedness asymmetry). The population showed split sex Ratios with about 89% of the colonies producing only males, resulting in an extremely male-biased Investment Ratio in the population. We make two important points with our data. First, we show that queen number may affect sex Ratio independently of relatedness asymmetry. Colonies producing only males had greater genetic effective queen number but did not have greater relatedness asymmetry from the perspective of the adult workers that rear the brood. This lack of a difference in relatedness asymmetry between colonies producing females and those producing only males was associated with a generally low relatedness between workers and brood. Second, studies that suggest support for the relatedness-asymmetry hypothesis based on indirect measures of relatedness asymmetry (e.g. queen number estimated from relatedness data taken from the brood only) should be considered with caution. We propose a new hypothesis that explains split sex Ratios in polygynous social insects based on the value of producing replacement queens.
Xia Xiao Hua - One of the best experts on this subject based on the ideXlab platform.
-
Ecological Economic Evaluation Based on Emergy as Embodied Cosmic Exergy: A Historical Study for the Beijing Urban Ecosystem 1978–2004
2010Co-Authors: Jiang Mei Ming, Chen Zhan-ming, Li Shuang Cheng, Xia Xiao HuaAbstract:For ecological economic evaluation based on the unified biophysical matrix this research illustrates an updated emergy synthesis in terms of embodied cosmic exergy instead of embodied solar energy, which successes the foundation of systems ecological theory but changes the starting point for the estimation from simply the sun to the cosmos. According to the modified definition implicating explicit scarcity and strict additivity based on the fundamental thermodynamics laws, the updated emergy approach overcomes the confusable and intractable deficiencies of traditional one and shows firmer theoretical basis as well as better applicability. As a case study for the regional socio-economic ecosystem, a cosmic emergy based ecological economic evaluation of the Beijing urban ecosystem during the period 1978-2004 is presented. The local and external resources supporting the concerned ecosystem are accounted and analyzed in a common unit, i.e., cosmic Joule, according to which a series of indicators are applied to reveal its evolutional characteristics through five aspects as emergy structure, emergy intensity, emergy welfare, environmental impacts, and degree of exploitation and economic efficiency. During the analyzed period, the major emergy source sustaining the opeRation of the ecosystem had changed from the renewable resources exploited locally to the nonrenewable resources purchased from outside. Emergy intensity for the Beijing urban ecosystem kept rising owing to the continuous Investment of resources, which not only improved the living standard but also intensified the environmental pressure. Moreover, the increase of exploitation degree was accompanied with the decline of economic efficiency, while the rising emergy Investment Ratio implicates that Beijing was at the risks of resources shortage and high dependence on external resource
-
Ecological Economic Evaluation Based on Emergy as Embodied Cosmic Exergy: A Historical Study for the Beijing Urban Ecosystem 1978-2004
2010Co-Authors: Jiang Mei Ming, Chen Zhan-ming, Li Shuang Cheng, Xia Xiao HuaAbstract:For ecological economic evaluation based on the unified biophysical matrix this research illustrates an updated emergy synthesis in terms of embodied cosmic exergy instead of embodied solar energy, which successes the foundation of systems ecological theory but changes the starting point for the estimation from simply the sun to the cosmos. According to the modified definition implicating explicit scarcity and strict additivity based on the fundamental thermodynamics laws, the updated emergy approach overcomes the confusable and intractable deficiencies of traditional one and shows firmer theoretical basis as well as better applicability. As a case study for the regional socio-economic ecosystem, a cosmic emergy based ecological economic evaluation of the Beijing urban ecosystem during the period 1978-2004 is presented. The local and external resources supporting the concerned ecosystem are accounted and analyzed in a common unit, i.e., cosmic Joule, according to which a series of indicators are applied to reveal its evolutional characteristics through five aspects as emergy structure, emergy intensity, emergy welfare, environmental impacts, and degree of exploitation and economic efficiency. During the analyzed period, the major emergy source sustaining the opeRation of the ecosystem had changed from the renewable resources exploited locally to the nonrenewable resources purchased from outside. Emergy intensity for the Beijing urban ecosystem kept rising owing to the continuous Investment of resources, which not only improved the living standard but also intensified the environmental pressure. Moreover, the increase of exploitation degree was accompanied with the decline of economic efficiency, while the rising emergy Investment Ratio implicates that Beijing was at the risks of resources shortage and high dependence on external resources.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000280347300003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, MultidisciplinarySCI(E)SSCI5ARTICLE71696-17201
Biagio F Giannetti - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of two hydropower plants in brazil using emergy for exploring regional possibilities
2016Co-Authors: C A Tassinari, S H Bonilla, F Agostinho, Cecilia M V B Almeida, Biagio F GiannettiAbstract:Abstract Two Brazilian hydropower plants (Jupia and Porto Primavera) located in the same watershed were explored in terms of the global resources needed to support these enterprises using a donor-side approach. Emergy theory and methods although commonly used by environmental scientists, may seem difficult to interpret for policy and decision-makers. Because of this, the possibility of transforming emergy flows and indices into money and area measures is explored in the present paper. Both hydropower plants deliver the same power and rely on practically the same infrastructure but involve very different flooded areas. Indirect areas calculated in terms of emergy show the different spatial distribution of resources. Some realistic alternatives for development were explored from both environmental and economic perspectives by using the emergy Investment Ratio and taking into account the matching between the enterprises emergy flows and the regional ones.
