title: Cost of flight and the evolution of stag beetle weaponry.
abstract: Male stag beetles have evolved extremely large mandibles in a wide range of extraordinary shapes. These mandibles function as weaponry in pugnacious fights for females. The robust mandibles of Cyclommatus metallifer are as long as their own body and their enlarged head houses massive, hypertrophied musculature. Owing to this disproportional weaponry, trade-offs exist with terrestrial locomotion: running is unstable and approximately 40% more costly. Therefore, flying is most probably essential to cover larger distances towards females and nesting sites. We hypothesized that weight, size and shape of the weaponry will affect flight performance. Our computational fluid dynamics simulations of steady-state models (without membrane wings) reveal that male stag beetles must deliver 26% more mechanical work to fly with their heavy weaponry. This extra work is almost entirely required to carry the additional weight of the massive armature. The size and shape of the mandibles have only negligible influence on flight performance (less than 0.1%). This indicates that the evolution of stag beetle weaponry is constrained by its excessive weight, not by the size or shape of the mandibles and head as such. This most probably paved the way for the wide diversity of extraordinary mandible morphologies that characterize the stag beetle family.
authors: Laboratory of Functional Morphology, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium Laboratory of Biophysics and BioMedical Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium jana.goyens@uantwerpen.be.
authors: Jana
authors: J
authors: Goyens
authors: Laboratory of Functional Morphology, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium.
authors: Sam
authors: S
authors: Van Wassenbergh
authors: Laboratory of Biophysics and BioMedical Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
authors: Joris
authors: J
authors: Dirckx
authors: Laboratory of Functional Morphology, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium Department of Movement and Sport Sciences, Ghent University, Watersportlaan 2, 9000 Ghent, Belgium.
authors: Peter
authors: P
authors: Aerts
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001835:Body Weight / Q000502:physiology*; D001517:Coleoptera / Q000502:physiology*; D003163:Competitive Behavior / Q000502:physiology; D003198:Computer Simulation; D004734:Energy Metabolism / Q000502:physiology; D005426:Flight, Animal / Q000502:physiology*; D008297:Male; D008334:Mandible / Q000502:physiology*; D008954:Models, Biological; D009929:Organ Size / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology
keywords: Lucanidae; computational fluid dynamics; cost of flight; mandible; sexual selection; stag beetle