Armament under direct sexual selection does not exhibit positive allometry in an earwig

Abstract

The allometric scaling relationships of armaments and ornaments have been subject to extensive debate. A large body of empirical evidence suggests that sexually selected traits typically exhibit positive static allometry, where the large individuals express proportionally larger traits. Recent theory suggests that this need not be the case. We confirm this prediction using the earwig Euborellia brunneri as a model species - unusually, the male armament in this species does not exhibit positive allometry. We experimentally assessed the strength of direct and indirect selection on armament length and morphology and on body size and weight. In a 3-stage experiment, we first permitted females to..