On the context‐dependent scaling of consumer feeding rates

Abstract

The stability of consumer-resource systems can depend on the form of feeding interactions (i.e. functional responses). Size-based models predict interactions -and thus stability -based on consumer-resource size ratios. However, little is known about how interaction contexts (e.g. simple or complex habitats) might alter scaling relationships. Addressing this, we experimentally measured interactions between a large size range of aquatic predators (4-6400 mg over 1347 feeding trials) and an invasive prey that transitions among habitats: from the water column (3D interactions) to simple and complex benthic substrates (2D interactions). Simple and complex substrates mediated successive reductions in capture rates -particularly around the unimodal optimumand promoted prey population stability in model simulations. Many real consumer-resource systems transition between 2D and 3D interactions, and along complexity gradients. Thus, ContextDependent Scaling (CDS) of feeding interactions could represent an unrecognised aspect of food webs, and quantifying the extent of CDS might enhance predictive ecology.

Small details of big importance: Carbon mass determination in the invasive cladoceran Cercopagis pengoi (Ostroumov, 1891) by the high temperature combustion method

“…Thus, body size of these organisms is recognized as a pivotal component of evolutionary fitness which provides a beneficial contribution to certain ecological patterns (Telesh et al 2015a(Telesh et al , 2016. Nevertheless, despite the long-recog-nized importance of body size in ecology, it is only recently that ecologists have begun to comprehensively resolve the body mass dependencies of consumer feeding rates, including the invasive predators (Barrios-O'Neill et al 2016, and references therein). In particular, body mass of C. pengoi was accounted as part of the algorithm which allows evaluating its predation impact (Telesh et al 2001, Laxson et al 2003, and this assessment can be used for monitoring of the invasion range and its effect on the natural zooplankton community.…”

frair: an R package for fitting and comparing consumer functional responses

“…This is likely because deviations from Type II towards Type III functional responses can stabilise otherwise chaotic consumer‐resource dynamics (Williams & Martinez ; Barrios‐O'Neill et al . ).…”

“…Unfortunately, the difference method does not allow for direct comparisons between predicted consumption across the range of resource densities and, because consumers can switch between Type II and Type III responses (Barrios‐O'Neill et al . ), objective comparisons using this approach are often impossible. Therefore, frair also provides frair_boot, which implements nonparametric bootstrapping and leverages boot::boot (Canty & Ripley ).…”

A trophic interaction framework for identifying the invasive capacity of novel organisms

“…Empirical examples of structured choices of prey in functional response studies of invasive species are rare (but see Barrios‐O'Neill et al., ; Dick et al., ; Xu et al., ). In our worked example of the marbled crayfish (Figure ), the mussel Dreissena spp.…”