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S R Carpenter - One of the best experts on this subject based on the ideXlab platform.
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food webs body size and species abundance in Ecological Community description
Advances in Ecological Research, 2005Co-Authors: Tomas Jonsson, J. E. Cohen, S R CarpenterAbstract:I. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 A. Trivariate Relationships. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 B. Bivariate Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 C. Univariate Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 D. EVect of Food Web Perturbation . . . . . . . . . . . . . . . . . . . . . . . . 4 I
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Food Webs, Body Size, and Species Abundance in Ecological Community Description
Advances in Ecological Research, 2005Co-Authors: Tomas Jonsson, J. E. Cohen, S R CarpenterAbstract:This chapter demonstrates that methods to describe Ecological communities can be better understood, and can reveal new patterns, by labeling each species that appears in a Community's food web with the numerical abundance and average body size of individuals of that species. We illustrate our new approach, and relate it to previous approaches, by analyzing data from the pelagic Community of a small lake, Tuesday Lake, in Michigan. Although many of the relationships we describe have been well studied individually, we are not aware of any single Community for which all of these relationships have been analyzed simultaneously. An overview of some of the results of the present study, with further theoretical extensions, has been published elsewhere (Cohen et al., 2003). Our new approach yields four major results. Though many patterns in the structure of an Ecological Community have been traditionally treated as independent, they are in fact connected. In at least one real ecosystem, many of these patterns are relatively robust after a major perturbation. Some of these patterns may be predictably consistent from one Community to another. Locally, however, some Community characteristics need not necessarily coincide with previously reported patterns for guilds or larger geographical scales. We describe our major findings under these headings: trivariate relationships (that is, relationships combining the food web, body size, and species abundance); bivariate relationships; univariate relationships; and the effects of food web perturbation. Trivariate Relationships: Species with small body mass occur low in the food web of Tuesday Lake and are numerically abundant. Larger-bodied species occur higher in the food web and are less numerically abundant. Body size explains more of the variation in numerical abundance than does trophic height. Body mass varies almost 12 orders of magnitude and numerical abundance varies by almost 10 orders of magnitude, but biomass abundance (the product of body mass times numerical abundance) varies by far less, about 5 orders of magnitude. The nearly inverse relationship between body mass and numerical abundance, and the relative constancy of biomass, are illustrated by a new food web graph (Fig. 3), which shows the food web in the plane with axes corresponding to body mass and numerical abundance. Bivariate Relationships: The pelagic Community of Tuesday Lake shows a pyramid of numbers but not a pyramid of biomass. The biomass of species increases very slowly with increasing body size, by only 2 orders of magnitude as body mass increases by 12 orders of magnitude. The biomass-body size spectrum is roughly flat, as in other studies at larger spatial scales. Prey body mass is positively correlated to predator body mass. Prey abundance and predator abundance are positively correlated for numerical abundance but not for biomass abundance. Body size and trophic height are positively correlated. Body size and numerical abundance are negatively correlated. The slope of the linear regression of log numerical abundance as a function of log body size in Tuesday Lake is not significantly different from -3{plus 45 degree rule}4 across all species but is significantly greater than -1 at the 5% significance level. This -3{plus 45 degree rule}4 slope is similar to that found in studies at larger, regional scales, but different from that sometimes observed at local scales. The slope within the phytoplankton and zooplankton (each group considered separately) is much less steep than -3{plus 45 degree rule}4, which is in agreement with an earlier observation that the slope tends to be more negative as the range of body masses of the organisms included in a study increases. A novel combination of the food web with data on body size and numerical abundance, together with an argument based on energetic mechanisms, refines and tightens the relationship between numerical abundance and body size. The regression of log body mass as a linear function of log numerical abundance across all species has a slope not significantly different from -1, but significantly less than -3{plus 45 degree rule}4. The estimated slope is significantly different from the reciprocal of the estimated slope of log numerical abundance as a function of log body mass. Thus, if log body mass is viewed as an independent variable and log numerical abundance is viewed as a dependent variable, the slope of the linear relationship could be -3{plus 45 degree rule}4 but could not be -1 at the 5% significance level. Conversely, if log numerical abundance is viewed as an independent variable and log body mass as a dependent variable, the slope of the linear relationship could be -1 but could not be -4{plus 45 degree rule}3 (which is the reciprocal of -3{plus 45 degree rule}4) at the 5% significance level. While a linear relationship is a good approximation in both cases, Cohen and Carpenter (in press) showed that only the model with log body mass as the independent variable meets the assumptions of linear regression analysis for these data. Univariate Relationships: The food web of Tuesday Lake has a pyramidal trophic structure. The number of trophic links between species in nearby trophic levels is higher than would be expected if trophic links were distributed randomly among the species. Food chains are shorter than would be expected if links were distributed randomly. Species low in the food web tend to have more predators and fewer prey than species high in the web. The distribution of body size is right-log skewed. The rank-numerical abundance relationship is approximately broken-stick within phytoplankton and zooplankton while the rank-biomass abundance relationship is approximately log-normal across all species. The slope of the right tail of the body mass distribution is much less steep than has been suggested for regional scales and not log-uniform as found at local scales for restricted taxonomic groups. Effect of Food Web Perturbation: The data analyzed here were collected in 1984 and 1986. In 1985, three species of planktivorous fishes were removed and one species of piscivorous fish was introduced. The data reveal some differences between 1984 and 1986 in the Community's species composition and food web. Most other Community characteristics seem insensitive to this major manipulation. Different fields of ecology have focused on different subsets of the bivariate relationships illustrated here. Integration of the relationships as suggested in this chapter could bring these fields closer. The new descriptive data structure (food web plus numerical abundance and body size of each species) can promote the integration of food web studies with, for example, population biology and biogeochemistry. © 2005 Elsevier Inc. All rights reserved.
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Ecological Community description using the food web, species abundance, and body size
Proceedings of the National Academy of Sciences, 2003Co-Authors: J. E. Cohen, Tomas Jonsson, S R CarpenterAbstract:Measuring the numerical abundance and average body size of individuals of each species in an Ecological Community's food web reveals new patterns and illuminates old ones. This approach is illustrated using data from the pelagic Community of a small lake: Tuesday Lake, Michigan, United States. Body mass varies almost 12 orders of magnitude. Numerical abundance varies almost 10 orders of magnitude. Biomass abundance (average body mass times numerical abundance) varies only 5 orders of magnitude. A new food web graph, which plots species and trophic links in the plane spanned by body mass and numerical abundance, illustrates the nearly inverse relationship between body mass and numerical abundance, as well as the pattern of energy flow in the Community. Species with small average body mass occur low in the food web of Tuesday Lake and are numerically abundant. Larger-bodied species occur higher in the food web and are numerically rarer. Average body size explains more of the variation in numerical abundance than does trophic height. The trivariate description of an Ecological Community by using the food web, average body sizes, and numerical abundance includes many well studied bivariate and univariate relationships based on subsets of these three variables. We are not aware of any single Community for which all of these relationships have been analyzed simultaneously. Our approach demonstrates the connectedness of Ecological patterns traditionally treated as independent. Moreover, knowing the food web gives new insight into the disputed form of the allometric relationship between body mass and abundance.
Tomas Jonsson - One of the best experts on this subject based on the ideXlab platform.
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food webs body size and species abundance in Ecological Community description
Advances in Ecological Research, 2005Co-Authors: Tomas Jonsson, J. E. Cohen, S R CarpenterAbstract:I. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 A. Trivariate Relationships. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 B. Bivariate Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 C. Univariate Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 D. EVect of Food Web Perturbation . . . . . . . . . . . . . . . . . . . . . . . . 4 I
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Food Webs, Body Size, and Species Abundance in Ecological Community Description
Advances in Ecological Research, 2005Co-Authors: Tomas Jonsson, J. E. Cohen, S R CarpenterAbstract:This chapter demonstrates that methods to describe Ecological communities can be better understood, and can reveal new patterns, by labeling each species that appears in a Community's food web with the numerical abundance and average body size of individuals of that species. We illustrate our new approach, and relate it to previous approaches, by analyzing data from the pelagic Community of a small lake, Tuesday Lake, in Michigan. Although many of the relationships we describe have been well studied individually, we are not aware of any single Community for which all of these relationships have been analyzed simultaneously. An overview of some of the results of the present study, with further theoretical extensions, has been published elsewhere (Cohen et al., 2003). Our new approach yields four major results. Though many patterns in the structure of an Ecological Community have been traditionally treated as independent, they are in fact connected. In at least one real ecosystem, many of these patterns are relatively robust after a major perturbation. Some of these patterns may be predictably consistent from one Community to another. Locally, however, some Community characteristics need not necessarily coincide with previously reported patterns for guilds or larger geographical scales. We describe our major findings under these headings: trivariate relationships (that is, relationships combining the food web, body size, and species abundance); bivariate relationships; univariate relationships; and the effects of food web perturbation. Trivariate Relationships: Species with small body mass occur low in the food web of Tuesday Lake and are numerically abundant. Larger-bodied species occur higher in the food web and are less numerically abundant. Body size explains more of the variation in numerical abundance than does trophic height. Body mass varies almost 12 orders of magnitude and numerical abundance varies by almost 10 orders of magnitude, but biomass abundance (the product of body mass times numerical abundance) varies by far less, about 5 orders of magnitude. The nearly inverse relationship between body mass and numerical abundance, and the relative constancy of biomass, are illustrated by a new food web graph (Fig. 3), which shows the food web in the plane with axes corresponding to body mass and numerical abundance. Bivariate Relationships: The pelagic Community of Tuesday Lake shows a pyramid of numbers but not a pyramid of biomass. The biomass of species increases very slowly with increasing body size, by only 2 orders of magnitude as body mass increases by 12 orders of magnitude. The biomass-body size spectrum is roughly flat, as in other studies at larger spatial scales. Prey body mass is positively correlated to predator body mass. Prey abundance and predator abundance are positively correlated for numerical abundance but not for biomass abundance. Body size and trophic height are positively correlated. Body size and numerical abundance are negatively correlated. The slope of the linear regression of log numerical abundance as a function of log body size in Tuesday Lake is not significantly different from -3{plus 45 degree rule}4 across all species but is significantly greater than -1 at the 5% significance level. This -3{plus 45 degree rule}4 slope is similar to that found in studies at larger, regional scales, but different from that sometimes observed at local scales. The slope within the phytoplankton and zooplankton (each group considered separately) is much less steep than -3{plus 45 degree rule}4, which is in agreement with an earlier observation that the slope tends to be more negative as the range of body masses of the organisms included in a study increases. A novel combination of the food web with data on body size and numerical abundance, together with an argument based on energetic mechanisms, refines and tightens the relationship between numerical abundance and body size. The regression of log body mass as a linear function of log numerical abundance across all species has a slope not significantly different from -1, but significantly less than -3{plus 45 degree rule}4. The estimated slope is significantly different from the reciprocal of the estimated slope of log numerical abundance as a function of log body mass. Thus, if log body mass is viewed as an independent variable and log numerical abundance is viewed as a dependent variable, the slope of the linear relationship could be -3{plus 45 degree rule}4 but could not be -1 at the 5% significance level. Conversely, if log numerical abundance is viewed as an independent variable and log body mass as a dependent variable, the slope of the linear relationship could be -1 but could not be -4{plus 45 degree rule}3 (which is the reciprocal of -3{plus 45 degree rule}4) at the 5% significance level. While a linear relationship is a good approximation in both cases, Cohen and Carpenter (in press) showed that only the model with log body mass as the independent variable meets the assumptions of linear regression analysis for these data. Univariate Relationships: The food web of Tuesday Lake has a pyramidal trophic structure. The number of trophic links between species in nearby trophic levels is higher than would be expected if trophic links were distributed randomly among the species. Food chains are shorter than would be expected if links were distributed randomly. Species low in the food web tend to have more predators and fewer prey than species high in the web. The distribution of body size is right-log skewed. The rank-numerical abundance relationship is approximately broken-stick within phytoplankton and zooplankton while the rank-biomass abundance relationship is approximately log-normal across all species. The slope of the right tail of the body mass distribution is much less steep than has been suggested for regional scales and not log-uniform as found at local scales for restricted taxonomic groups. Effect of Food Web Perturbation: The data analyzed here were collected in 1984 and 1986. In 1985, three species of planktivorous fishes were removed and one species of piscivorous fish was introduced. The data reveal some differences between 1984 and 1986 in the Community's species composition and food web. Most other Community characteristics seem insensitive to this major manipulation. Different fields of ecology have focused on different subsets of the bivariate relationships illustrated here. Integration of the relationships as suggested in this chapter could bring these fields closer. The new descriptive data structure (food web plus numerical abundance and body size of each species) can promote the integration of food web studies with, for example, population biology and biogeochemistry. © 2005 Elsevier Inc. All rights reserved.
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Ecological Community description using the food web, species abundance, and body size
Proceedings of the National Academy of Sciences, 2003Co-Authors: J. E. Cohen, Tomas Jonsson, S R CarpenterAbstract:Measuring the numerical abundance and average body size of individuals of each species in an Ecological Community's food web reveals new patterns and illuminates old ones. This approach is illustrated using data from the pelagic Community of a small lake: Tuesday Lake, Michigan, United States. Body mass varies almost 12 orders of magnitude. Numerical abundance varies almost 10 orders of magnitude. Biomass abundance (average body mass times numerical abundance) varies only 5 orders of magnitude. A new food web graph, which plots species and trophic links in the plane spanned by body mass and numerical abundance, illustrates the nearly inverse relationship between body mass and numerical abundance, as well as the pattern of energy flow in the Community. Species with small average body mass occur low in the food web of Tuesday Lake and are numerically abundant. Larger-bodied species occur higher in the food web and are numerically rarer. Average body size explains more of the variation in numerical abundance than does trophic height. The trivariate description of an Ecological Community by using the food web, average body sizes, and numerical abundance includes many well studied bivariate and univariate relationships based on subsets of these three variables. We are not aware of any single Community for which all of these relationships have been analyzed simultaneously. Our approach demonstrates the connectedness of Ecological patterns traditionally treated as independent. Moreover, knowing the food web gives new insight into the disputed form of the allometric relationship between body mass and abundance.
J. E. Cohen - One of the best experts on this subject based on the ideXlab platform.
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food webs body size and species abundance in Ecological Community description
Advances in Ecological Research, 2005Co-Authors: Tomas Jonsson, J. E. Cohen, S R CarpenterAbstract:I. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 A. Trivariate Relationships. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 B. Bivariate Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 C. Univariate Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 D. EVect of Food Web Perturbation . . . . . . . . . . . . . . . . . . . . . . . . 4 I
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Food Webs, Body Size, and Species Abundance in Ecological Community Description
Advances in Ecological Research, 2005Co-Authors: Tomas Jonsson, J. E. Cohen, S R CarpenterAbstract:This chapter demonstrates that methods to describe Ecological communities can be better understood, and can reveal new patterns, by labeling each species that appears in a Community's food web with the numerical abundance and average body size of individuals of that species. We illustrate our new approach, and relate it to previous approaches, by analyzing data from the pelagic Community of a small lake, Tuesday Lake, in Michigan. Although many of the relationships we describe have been well studied individually, we are not aware of any single Community for which all of these relationships have been analyzed simultaneously. An overview of some of the results of the present study, with further theoretical extensions, has been published elsewhere (Cohen et al., 2003). Our new approach yields four major results. Though many patterns in the structure of an Ecological Community have been traditionally treated as independent, they are in fact connected. In at least one real ecosystem, many of these patterns are relatively robust after a major perturbation. Some of these patterns may be predictably consistent from one Community to another. Locally, however, some Community characteristics need not necessarily coincide with previously reported patterns for guilds or larger geographical scales. We describe our major findings under these headings: trivariate relationships (that is, relationships combining the food web, body size, and species abundance); bivariate relationships; univariate relationships; and the effects of food web perturbation. Trivariate Relationships: Species with small body mass occur low in the food web of Tuesday Lake and are numerically abundant. Larger-bodied species occur higher in the food web and are less numerically abundant. Body size explains more of the variation in numerical abundance than does trophic height. Body mass varies almost 12 orders of magnitude and numerical abundance varies by almost 10 orders of magnitude, but biomass abundance (the product of body mass times numerical abundance) varies by far less, about 5 orders of magnitude. The nearly inverse relationship between body mass and numerical abundance, and the relative constancy of biomass, are illustrated by a new food web graph (Fig. 3), which shows the food web in the plane with axes corresponding to body mass and numerical abundance. Bivariate Relationships: The pelagic Community of Tuesday Lake shows a pyramid of numbers but not a pyramid of biomass. The biomass of species increases very slowly with increasing body size, by only 2 orders of magnitude as body mass increases by 12 orders of magnitude. The biomass-body size spectrum is roughly flat, as in other studies at larger spatial scales. Prey body mass is positively correlated to predator body mass. Prey abundance and predator abundance are positively correlated for numerical abundance but not for biomass abundance. Body size and trophic height are positively correlated. Body size and numerical abundance are negatively correlated. The slope of the linear regression of log numerical abundance as a function of log body size in Tuesday Lake is not significantly different from -3{plus 45 degree rule}4 across all species but is significantly greater than -1 at the 5% significance level. This -3{plus 45 degree rule}4 slope is similar to that found in studies at larger, regional scales, but different from that sometimes observed at local scales. The slope within the phytoplankton and zooplankton (each group considered separately) is much less steep than -3{plus 45 degree rule}4, which is in agreement with an earlier observation that the slope tends to be more negative as the range of body masses of the organisms included in a study increases. A novel combination of the food web with data on body size and numerical abundance, together with an argument based on energetic mechanisms, refines and tightens the relationship between numerical abundance and body size. The regression of log body mass as a linear function of log numerical abundance across all species has a slope not significantly different from -1, but significantly less than -3{plus 45 degree rule}4. The estimated slope is significantly different from the reciprocal of the estimated slope of log numerical abundance as a function of log body mass. Thus, if log body mass is viewed as an independent variable and log numerical abundance is viewed as a dependent variable, the slope of the linear relationship could be -3{plus 45 degree rule}4 but could not be -1 at the 5% significance level. Conversely, if log numerical abundance is viewed as an independent variable and log body mass as a dependent variable, the slope of the linear relationship could be -1 but could not be -4{plus 45 degree rule}3 (which is the reciprocal of -3{plus 45 degree rule}4) at the 5% significance level. While a linear relationship is a good approximation in both cases, Cohen and Carpenter (in press) showed that only the model with log body mass as the independent variable meets the assumptions of linear regression analysis for these data. Univariate Relationships: The food web of Tuesday Lake has a pyramidal trophic structure. The number of trophic links between species in nearby trophic levels is higher than would be expected if trophic links were distributed randomly among the species. Food chains are shorter than would be expected if links were distributed randomly. Species low in the food web tend to have more predators and fewer prey than species high in the web. The distribution of body size is right-log skewed. The rank-numerical abundance relationship is approximately broken-stick within phytoplankton and zooplankton while the rank-biomass abundance relationship is approximately log-normal across all species. The slope of the right tail of the body mass distribution is much less steep than has been suggested for regional scales and not log-uniform as found at local scales for restricted taxonomic groups. Effect of Food Web Perturbation: The data analyzed here were collected in 1984 and 1986. In 1985, three species of planktivorous fishes were removed and one species of piscivorous fish was introduced. The data reveal some differences between 1984 and 1986 in the Community's species composition and food web. Most other Community characteristics seem insensitive to this major manipulation. Different fields of ecology have focused on different subsets of the bivariate relationships illustrated here. Integration of the relationships as suggested in this chapter could bring these fields closer. The new descriptive data structure (food web plus numerical abundance and body size of each species) can promote the integration of food web studies with, for example, population biology and biogeochemistry. © 2005 Elsevier Inc. All rights reserved.
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Ecological Community description using the food web, species abundance, and body size
Proceedings of the National Academy of Sciences, 2003Co-Authors: J. E. Cohen, Tomas Jonsson, S R CarpenterAbstract:Measuring the numerical abundance and average body size of individuals of each species in an Ecological Community's food web reveals new patterns and illuminates old ones. This approach is illustrated using data from the pelagic Community of a small lake: Tuesday Lake, Michigan, United States. Body mass varies almost 12 orders of magnitude. Numerical abundance varies almost 10 orders of magnitude. Biomass abundance (average body mass times numerical abundance) varies only 5 orders of magnitude. A new food web graph, which plots species and trophic links in the plane spanned by body mass and numerical abundance, illustrates the nearly inverse relationship between body mass and numerical abundance, as well as the pattern of energy flow in the Community. Species with small average body mass occur low in the food web of Tuesday Lake and are numerically abundant. Larger-bodied species occur higher in the food web and are numerically rarer. Average body size explains more of the variation in numerical abundance than does trophic height. The trivariate description of an Ecological Community by using the food web, average body sizes, and numerical abundance includes many well studied bivariate and univariate relationships based on subsets of these three variables. We are not aware of any single Community for which all of these relationships have been analyzed simultaneously. Our approach demonstrates the connectedness of Ecological patterns traditionally treated as independent. Moreover, knowing the food web gives new insight into the disputed form of the allometric relationship between body mass and abundance.
K. Itoh - One of the best experts on this subject based on the ideXlab platform.
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An explanatory model for food-web structure and evolution
Ecological Complexity, 2005Co-Authors: Axel G. Rossberg, H. Matsuda, Tomohiro Amemiya, K. ItohAbstract:Food webs are networks describing who is eating whom in an Ecological Community. By now it is clear that many aspects of food-web structure are reproducible across diverse habitats, yet little is known about the driving force behind this structure. Evolutionary and population dynamical mechanisms have been considered. We propose a model for the evolutionary dynamics of food-web topology and show that it accurately reproduces observed food-web characteristics in the steady state. It is based on the observation that most consumers are larger than their resource species and the hypothesis that speciation and extinction rates decrease with increasing body mass. Results give strong support to the evolutionary hypothesis. © 2005 Elsevier B.V. All rights reserved.
Axel G. Rossberg - One of the best experts on this subject based on the ideXlab platform.
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An explanatory model for food-web structure and evolution
Ecological Complexity, 2005Co-Authors: Axel G. Rossberg, H. Matsuda, Tomohiro Amemiya, K. ItohAbstract:Food webs are networks describing who is eating whom in an Ecological Community. By now it is clear that many aspects of food-web structure are reproducible across diverse habitats, yet little is known about the driving force behind this structure. Evolutionary and population dynamical mechanisms have been considered. We propose a model for the evolutionary dynamics of food-web topology and show that it accurately reproduces observed food-web characteristics in the steady state. It is based on the observation that most consumers are larger than their resource species and the hypothesis that speciation and extinction rates decrease with increasing body mass. Results give strong support to the evolutionary hypothesis. © 2005 Elsevier B.V. All rights reserved.
