[ Back to EurekAlert! ] Public release date: 25-Jun-2007
[ | E-mail Share Share ]

Contact: Patricia Morse
pmorse@uchicago.edu
773-702-0446
University of Chicago Press Journals

The beetle's dilemma

Trade-offs between force and fit shape beetles

IMAGE: A carabid beetle inserting its head into a snail shell.

Click here for more information.

Large jaws are efficient in crushing hard prey, whereas small jaws are functional in capturing elusive prey. Researchers have suggested that such trade-offs between “force” and “velocity” could cause evolutionary diversification of morphology in animals such as birds, fish, and salamanders. Junji Konuma and Satoshi Chiba of Tohoku University found that a new trade-off exists in animal feeding behavior. The team suggests that diversification of carabid beetles could be caused by a “force” and “fit” trade-off.

There are both elongate, small-headed and stout, large-headed carabid beetles that feed upon land snails. Large-headed beetles can readily crush snail shells with their powerful jaws, but cannot insert their oversized heads into the shells. In contrast, small-headed beetles can insert their heads into the shells for direct predation on snail bodies, but poorly crush the shells because of their frugal jaws. “Crushing and inserting are alternatively effective in feeding on snails,” said Konuma. Carabid beetles that feed on snails tend to have an extremely slender or stout forebody compared with beetles that eat insects and earthworms. Phylogenetic studies show that adaptations for snail feeding led to the diversification of beetle heads. Interestingly, it has been demonstrated that the same trade-off diversifies shell morphology in studies of freshwater snails, where elongate shells are adaptive in protecting against entry attacks and rounded shells are adaptive in protecting against crushing attacks. “Trade-offs between force and fit have a significant, important role in both morphologies of snails and snail predators in evolution,” said Konuma.

###

Junji Konuma and Satoshi Chiba, "Trade-offs between force and fit: extreme morphologies associated with feeding behavior in carabid beetles" The American Naturalist (2007) 170:90–100 DOI: 10.1086/518182

Founded in 1867, The American Naturalist is one of the world's most renowned, peer-reviewed publications in ecology, evolution, and population and integrative biology research. AmNat emphasizes sophisticated methodologies and innovative theoretical syntheses—all in an effort to advance the knowledge of organic evolution and other broad biological principles.



[ Back to EurekAlert! ] [ | E-mail Share Share ]

 


AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.