This suggests that the relationship between functional response shape and body mass ratios may vary with predation mode. In addition, our estimates of b for filter-feeding Daphnia are much smaller than predicted for actively hunting predators at similar consumerвЂ“resource body mass ratios. This causes a delay between when the prey begins to increase and when the predator detects the increase and switches effort. Accurate parameter estimation may therefore require fitting to both rates. Type 3 Functional Response sigmoid-shaped curve possibly due to prey switching, which can occur when the predator concentrates on the prey species with the largest densities. Remarkably, stability predictions differ depending on whether functional response parameters are derived from clearance vs. Parameterized type III responses are predicted to stabilize the modeled DaphniaвЂ“phytoplankton dynamics in some species pairs but not in others. All experimentally studied DaphniaвЂ“algae systems exhibited type III responses. Functional response parameters were experimentally derived for two species of Daphnia feeding separately on single cultures of two different phytoplankton species. We derive a novel analytical condition relating b to local stability of consumerвЂ“resource interactions and use it to predict stability of empirically parameterized models of Daphnia and phytoplankton under enrichment. Specifically, the shape of the functional response of the pelagic grazer Daphnia feeding on phytoplankton, and its consequences for stability, remain controversial. The dependence of consumerвЂ“resource stability on b has, however, not been systematically explored, and the accurate empirical determination of b is challenging. Larger consumerвЂ“resource body mass ratios have been suggested to generate more pronounced type III responses and therefore to promote dynamic stability.

Empirical estimates of b vary considerably across taxa. The curvature of generalized Holling type functional response curves is controlled by a shape parameter b yielding hyperbolic type II ( b = 1) to increasingly sigmoid type III ( b > 1) responses.

Type 3 functional response