Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the...

1. The castes of social insects can vary dramatically in physiology, morphology and behaviour, and are a model of phenotypic plasticity. Dietary variation has been implicated in the evolution of castes and is involved in developmental differentiation. This study uses the elemental and isotopic composition of castes to infer the diets they consumed during larval development, when caste was deter...

in this study, three stations of the north persian gulf were analyzed in order to determinethe effect of trophic levels on the concentration of harmful pahs in fish and sediment. in all cases,similar distributions were observed in which benzo(a)pyrene largely predominated andbenzo(b)fluoranthene and pyrene were the second major compounds in fish tissues. the predominantcomponents of pahs in sed...

Ecological niche theory predicts that coexistence is facilitated by resource partitioning mechanisms that are influenced by abiotic and biotic interactions. Alternative hypotheses suggest that under certain conditions, species may become phenotypically similar and functionally equivalent, which invokes the possibility of other mechanisms, such as habitat filtering processes. To test these hypot...

Rationale Ecologists increasingly determine the ?15N values of amino acids (AA) in animal tissue; “source” AA typically exhibit minor variation between diet and consumer, while “trophic” have increased consumers. Thus, trophic-source offsets (i.e., ?15NT-S) reflect trophic position a food web. However, even variations ?15Nsource may influence magnitude offset that represents step, known as disc...