The models based on head

size (zygoWidth, muscleMass and skullMass) CH5424802 cost outperformed a model of overall size, bodyMass (Table 2). This is reasonable to us because size of head, the apparatus responsible for bite force, should be a better predictor of bite force than body size. Within the head size models the simple zygoWidth did not predict as well as muscleMass or skullMass. The muscleCalc model worked better than the either skullMass or muscleMass, which might be expected because muscleCalc takes into account the input and output arms of the jaw. The possible exception to this rule is the modest success of the Thomason model, which was clearly better than body size, but otherwise the worst predictor. Our two-variable model, comboModel, is a clear winner over the next best model, beamCalc, with an AIC difference of 12. However on a practical note, the advantage of using beamCalc alone is that not only is it reasonably effective compared with the best model (beamCalc explains 91% of the variation in bite force while comboModel explains 94%) but also can be measured easily on a museum specimen or fossil. In comboModel the component, muscleCalc, requires dissecting fresh muscles. Further, although beamCalc and comboModel are free of phylogenetic effects, the muscleCalc model is influenced by phylogeny. We recommend the beamCalc model as the most practical method to predict bite

force because it combines simplicity of measurement and predictive power. However if fresh material is available the comboModel would be preferred. Freeman’s (1979, 1981a,b) view of eco-morphological space was that bats exist on a continuum MK-2206 datasheet from robust bats with relatively strong biting species for their size that are eating hard-bodied insects, to gracile bats that have relatively weak bites and consume soft prey. Our results do not totally support this view of ecomorphology in insectivorous bats. Baf-A1 supplier She maintained that gracile forms such

as Corynorhinus, Tadarida, Nyctinomops, Eumops, and Mormoops should be weak-biting bats (Freeman, 1979, 1981a,b). In Fig. 2 we plotted the six gracile species as open circles. These bats are indeed weak biters for their body mass. She also predicted that Molossus, Lasiurus and Noctilio, would have powerful bites (they are plotted as open triangles in Fig. 2), but these bats have only average bite forces. Therefore we can verify Freeman’s inference for gracile, weak-biting bats, but not for hard-biting species. However, several species that Freeman predicted should have strong bites have not yet been measured for bite force. Perhaps other species will yet fill the role of a hard-biting insectivorous bat. Further research will be needed to understand the relative importance of this robust-gracile axis in the adaptive radiation of bats as bite force information becomes available for a broader array of insectivorous bats. We particularly thank our colleagues K. Geluso, M.J. Harner, K.N. Geluso, M. Bogan, and T.