Functional mechanics of beetle mandibles: Honest signaling in a sexually selected system
Abstract
Male stag beetles possess colossal mandibles, which they wield in combat to obtain access to females. As with many other sexually selected weapons, males with longer mandibles win more fights. However, variation in the functional morphology of these structures, used in male‐male combat, is less well understood. In this study, mandible bite force, gape, structural strength, and potential tradeoffs are examined across a wide size range for one species of stag beetle, Cyclommatus metallifer. We found that not only does male mandible size demonstrate steep positive allometry, but the shape, relative bite force, relative gape, and safety factor of the mandibles also change with male size. Allometry in these functionally important mandibular traits suggests that larger males with larger mandibles should be better fighters, and that the mandibles can be considered an honest signal of male fighting ability. However, negative allometry in mandible structural safety factor, wing size, and flight muscle mass suggest significant costs and a possible limit on the size of the mandibles. J. Exp. Zool. 325A:3–12, 2016. © 2015 Wiley Periodicals, Inc.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 09, 2015
- Source ID
- 10.1002/jez.1961
Entities
People
- Brook O. Swanson
- Emily A. Carlson
- Hiroki Gotoh
- Laura C. Lavine
- Maria R. Mills
- Rahmi S. Nemri
- William Wilde
Organizations
- Air Force Office of Scientific Research
- Gonzaga University
- Japan Society for the Promotion of Science
- National Science Foundation
- Washington State University