title: Trade-offs between force and fit: extreme morphologies associated with feeding behavior in carabid beetles.
abstract: We explored how functional trade-offs in resource handling strategies are associated with the divergent morphology of predators. The malacophagous carabid Damaster blaptoides shows two extreme morphologies in the forebody; there is an elongate small-headed type and a stout large-headed type. A feeding experiment showed that the small-headed type obtained a high feeding performance on snails with a thick shell and a large aperture by penetrating the shell with its head. In contrast, the large-headed type showed a high feeding performance on snails that had a thin shell and a small aperture, and they ate these prey by crushing the shell. The large-headed, strong-jawed beetles are efficient at shell crushing but are ineffective at shell entry; the large mandibles and musculature that allow for shell crushing make the beetle's head too wide to penetrate shell apertures. On the other hand, small-headed, weak-jawed beetles crush poorly but can reach into shells for direct predation on snail bodies. These findings are hypothesized to be functional trade-offs between force and fit due to morphological constraints. This trade-off would be a primary mechanism affecting both resource handling ability in animals and phenotypic diversity in predators and prey.
authors.affiliation: Department of Ecology and Evolutionary Biology, Graduate School of Life Sciences, University of Tohoku, Aobayama, Sendai, Japan. konuma@mail.tains.tohoku.ac.jp
authors.forename: Junji
authors.initials: J
authors.lastname: Konuma
authors.forename: Satoshi
authors.initials: S
authors.lastname: Chiba
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001517:Coleoptera / Q000033:anatomy & histology / Q000502:physiology*; D005247:Feeding Behavior; D010641:Phenotype; D011235:Predatory Behavior; D012908:Snails / Q000033:anatomy & histology; D013045:Species Specificity