Understanding the processes underlying food-web structure and organization remains one of the major tasks of ecology. While first attempts were mostly based on niche theory, with body size of species imposing a hierarchical structure for consumer species, it has been recently suggested that phylogenetic constraints may be more fundamental to understand who eats whom in natural communities. Mode...

The effect of tillage intensity on nematode community trophic structure and the role of nematodes in the regulation of decomposition rates in agroecosystems were examined. Conventional (CT) and no-tillage (NT) agroecosystems were sampled monthly for 1 year. Tillage affected nematode trophic structure and total abundance. Monthly mean densities of bacterivorous, fungivorous, and total nematodes ...

Divergence in habitat use among closely related species is a common characteristic of adaptive radiations. Large differences in the size structure of prey between habitats could strengthen disruptive selection on generalist predators and lead to a divergence in trophic position among species in an adaptive radiation. Using threespine stickleback (Gasterosteus aculeatus) in freshwater lakes as a...

Body size exerts multiple effects on plankton food-web interactions. However, the influence of size structure on trophic transfer remains poorly quantified in the field. Here, we examine how the size diversity of prey (nano-microplankton) and predators (mesozooplankton) influence trophic transfer efficiency (using biomass ratio as a proxy) in natural marine ecosystems. Our results support previ...

An examination of the trophic status of a cryptobenthic reef fish community from the central Great Barrier Reef was carried out to evaluate the potential role of cryptobenthic fishes in coral reef ecosystems. Using frequency of occurrence data, dietary analyses revealed a diverse range of trophic groups, although detritivory (in 10 out of 16 species and 39.3% of individuals) and carnivory (5 of...

We present a graph theoretic model of analysing food web structure called regular equivalence. Regular equivalence is a method for partitioning the species in a food web into "isotrophic classes" that play the same structural roles, even if they are not directly consuming the same prey or if they do not share the same predators. We contrast regular equivalence models, in which two species are m...

In a field study conducted in Georgia, cucurbit plants with high (Cucurbita andreana) and low (Cucurbita maxima) concentrations of cucurbitacins were used in combination with two types of fertilizers to investigate their effects on the community of soil nematodes. Ecological measures of soil nematode community structure such as total nematode abundance, number of genera, trophic diversity, trop...

PURPOSE To characterize secretion of in situ retinal pigment epithelium (RPE) from healthy, aged adult, age-related macular degeneration (AMD) adult, and fetal donor eyes and to assess the impact on retinal survival in vitro. METHODS Conditioned medium (CM) was collected from adult and fetal donor eyes and analyzed for trophic factor composition by multiplex ELISA. Trophic factor receptor occ...

Anthropogenic disturbances intertwined with climatic changes can have a large impact on the upper trophic levels of marine ecosystems, which may cascade down the food web. So far it has been difficult to demonstrate multi-level trophic cascades in pelagic marine environments. Using field data collected during a 33-year period, we show for the first time a four-level community-wide trophic casca...