Figure : Functional response (prey consumed per predator) observations for various predator and prey densities of the Stenostomum virginanum-Paramecium aurelia predator-prey system, along with fitted model predictions (line represents mean; shaded area the standard deviation of model posterior distribution). a) Ratio dependent Type III equation, b) Hassell-Varley Type III equation, c) Beddington-DeAngelis equation, d) Kovai equation. N indicates the prey density. Data from (Kratina et al. 2009).
Figure 2 shows the applicability of various equation types across all datasets used in this study. Given the Kovai equation’s ability to adjust to both Type II and Type III functional responses, we expected it to show more consistent applicability across datasets with varying functional response forms than pure Type II or Type III equations (regardless of prey or ratio dependence). Datasets were classified by their level of (dis)similarity to a Type II functional response, using the average rank of Type II equations’ fit (as compared to the fit of equations with different functional responses) when fitted to the data. Figure 2 compares the average rank (lower indicates better fit relative to other equations) of different equation groups with the average rank of Type II response equations for each of the different datasets.