Observational approach

Quantifying the effects of intraspecific variation on predator feeding rates through nonlinear averaging

Theory suggests that intraspecific trait variation will alter species interaction strengths through nonlinear averaging when interaction strengths are nonlinear functions of individuals' traits. This effect is expected to be widespread, yet what …

Trematode parasites exceed aquatic insect biomass in Oregon stream food webs

Although parasites are increasingly recognized for their ecosystem roles, it is often assumed that free-living organisms dominate animal biomass in most ecosystems and therefore provide the primary pathways for energy transfer. To examine the …

Food-web interaction strength distributions are conserved by greater variation between than within predator--prey pairs

Species interactions in food webs are usually recognized as dynamic, varying across species, space, and time because of biotic and abiotic drivers. Yet food webs also show emergent properties that appear consistent, such as a skewed frequency …

What drives interaction strengths in complex food webs? A test with feeding rates of a generalist stream predator

Describing the mechanisms that drive variation in species interaction strengths is central to understanding, predicting, and managing community dynamics. Multiple factors have been linked to trophic interaction strength variation, including species …

Bayesian characterization of uncertainty in species interaction strengths

Considerable effort has been devoted to the estimation of species interaction strengths. This effort has focused primarily on statistical significance testing and obtaining point estimates of parameters that contribute to interaction strength …

Quantifying predator dependence in the functional response of generalist predators

A long‐standing debate concerns how functional responses are best described. Theory suggests that ratio dependence is consistent with many food web patterns left unexplained by the simplest prey‐dependent models. However, for logistical reasons, …

Using Survival Models to Estimate Invertebrate Prey Identification Times in a Generalist Stream Fish

Estimates of predator feeding rates are important for understanding trophic dynamics. One common method for quantifying feeding rates in fishes combines mass‐based diet data with gastric evacuation times to estimate prey mass consumed per predator. …

Trophic omnivory across a productivity gradient: intraguild predation theory and the structure and strength of species interactions

Intraguild predation theory centres on two predictions: (i) for an omnivore and an intermediate predator (IG-prey) to coexist on shared resources, the IG-prey must be the superior resource competitor, and (ii) increasing resource productivity causes …

Estimating interaction strengths in nature: experimental support for an observational approach

The complexity of food webs poses a significant hurdle for our growing understanding of the structure and dynamics of ecological communities. Empirical methods that measure the per capita strengths of trophic species interactions offer a means to …

Estimating nonlinear interaction strengths: an observation-based method for species-rich food webs

Efforts to estimate the strength of species interactions in species‐rich, reticulate food webs have been hampered by the multitude of direct and indirect interactions such systems exhibit and have been limited by an assumption that pairwise …