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Accounting for the variation that occurs within species in food webs can theoretically result in significant changes in both network structure and dynamics. However, there has been little work exploring their role with empirical data. In particular, the variation associated with species' life cycles, which is prevalent and represents both trait variation and taxonomic identity, has received little attention. Here, we characterize the structural consequences of life stage variation in five food webs, including a newly compiled web from the Arabian Gulf. We show that making life stage variation explicit in food webs results in larger food webs that possess consistent structural changes that are separate from the changes in structure that come simply from increasing the number of nodes in the webs. Furthermore, we show that the magnitude of these changes is related to ontogenetic specialism, the degree of overlap in the ecological niches of life stages. These results demonstrate the capacity of intraspecific variation to affect ecological networks and indicate the potential usefulness of stage‐structured food webs, which capture size and taxonomic information, to represent variation below the species level. [ABSTRACT FROM AUTHOR]

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A general question in biology is how processes at one scale, for example that of individual organisms, influence patterns at larger scales, for example communities of interacting individuals. Here we ask how changing the size-dependence of the foraging behaviour of individuals can influence the structure of food webs. We assembled communities using a model in which species interactions are determined by allometric foraging rules of (1) handling time and (2) attack rates, and also (3) the distribution of body sizes. We systematically varied these three factors and examined their effects on three community level, food web allometries: the generality - mass correlation, the vulnerability - mass correlation and the trophic height - mass correlation. The results demonstrate how allometries of individual foraging behaviour (handling time and attack rates) are linked across scales of organisation: different community level allometries are influenced by different individual level allometries. For example, generality allometries in the community are most affected by the individual allometric relationships of the attack rate, whereas trophic level allometries in the community are more strongly influenced by variation in individual handling time allometries. Importantly, we also find that the shape of the body size distribution from which species are drawn has a substantial influence on how these links between scales operate. This study suggests that understanding the variation of size structure among ecological networks requires knowledge about the causes of variation in individual foraging behaviour and determinants of the regional body size distribution. [ABSTRACT FROM AUTHOR]

Abstract. Climate change is expected to alter trophic interactions within food chains, but predicting the fate of particular species is difficult because the predictions hinge on knowing exactly how climate influences direct and indirect interactions. We used two complementary approaches to examine how climate change may alter trophic interactions within an old-field food web composed of herbaceous plants, grasshopper herbivores, and spider predators. We synthesized data spanning 15 years of experimentation during which interannual mean growing season temperature varied by 2°C and precipitation by 2.5 cm. We also manipulated temperature within mesocosms to test the affect of temperature on primary production and strength of direct and indirect trophic interactions. Both approaches produced similar results: plant production was not directly affected by temperature or precipitation, but the strength of top-down indirect effects on grasses and forbs increased by 30-40% per 1°C. Hence, the net effect of climate change was to strengthen top-down control of this terrestrial system. [ABSTRACT FROM AUTHOR]

The article provides information on the issue regarding the parasites cited on the nature's food web system. It mentions the relevance of food web in maintaining and keeping the ecosystem in check and cites the continuous relationship between producers and consumers and between predators and prey. Meanwhile, there are some food web researches have included parasites and pathogenic creatures and notes their contributions to the food web system. Moreover, the significance of these pathogenic parasites for the maintenance and balance of ecology is also discussed.

Food webs, the networks of feeding links between species, are central to our understanding of ecosystem structure, stability, and function. One of the key aspects of food web structure is complexity, or connectance, the number of links expressed as a pro- portion of the total possible number of links. Connectance (complexity) is linked to the stability of webs and is a key parameter in recent models of other aspects of web structure. However, there is still no fundamental biological explanation for connectance in food webs. Here, we propose that constraints on diet breadth, driven by optimal foraging, provide such an explanation. We show that a simple diet breadth model predicts highly constrained values of connectance as an emergent consequence of individual foraging behavior. When combined with features of real food web data, such as taxonomic and trophic aggregation and cumulative sampling of diets, the model predicts well the levels of connectance and scaling of connectance with species richness, seen in real food webs. This result is a previously undescribed synthesis of foraging theory and food web theory, in which network properties emerge from the behavior of individuals and, as such, provides a mechanistic explanation of connectance currently lacking in food web models. [ABSTRACT FROM AUTHOR]

Presents information on a study conducted on trophic cascades which are categorized as important signals for top-down control of food web dynamics. Methodology used to conduct the study; Results of the study; Examination of the treatment.

Presents information on an experiment focusing on the behavioral pattern within a terrestrial food chain. How can predators of herbivorous animals affect plant populations; Examination of the dynamics of the terrestrial food chain; Contents of ecological literature.

Abstract: Revealing the processes that determine who eats whom, and thereby the structure of food webs, is a long running challenge in ecological research. Recent advances include development of new methods for measuring fit of models to observed food web data, and thereby testing which are the ‘best’ food web models. The best model could be considered the most efficient with relatively few parameters and high explanatory power. Another recent advance involves adding some additional biology to food web models in the form of foraging theory based on maximisation of energy intake as the predictor of species'' diets in food webs. While it is interesting to compare efficiency among food web models, we believe that such comparisons at least should be interpreted with caution, since they do not account for any differences in motivation, formulation, and potential that might also exist among models. Furthermore, we see an important but somewhat neglected role for experimental tests of models of food web structure. [Copyright &y& Elsevier]