Sprint speed is not reduced by exaggerated male weapons in a flower beetle Dicronocephalus wallichii

AbstractExaggerated sexually selected traits are assumed to decrease the mobility of bearers. However, previous empirical studies have often failed to support this assumption, possibly because locomotor performance represents the integration of numerous morphological, physiological and behavioural traits. Males of a flower beetleDicronocephalus wallichii Pouillaude 1914 (Coleoptera: Scarabaeidae: Cetoniinae) possess elongated forelegs and a pair of exaggerated horns, which are used as dual weapons in male –male competition for mates. We investigated whether these two sexual traits impede the maximum sprint speed on bamboo branches with different angles and thicknesses under laboratory conditions. Our results suggested that no negative relationship exists between relative foreleg length or horn leng th and sprint speed. Elongated forelegs and horns may entail negligible locomotor costs. Males with longer horns and forelegs were found to have longer midlegs and hindlegs independent of body size. Thus, elongated midlegs and hindlegs in males may enhance balance, stabilize running on bamboo branch es and compensate for the locomotor costs of bearing exaggerated weapons. Furthermore, a positive relationship was found between horn length and sprint speed on a horizontal branch. Males with longer horns probably have more energy and/or invest more heavily in appendage musculature. As is known in other animals, male horns ofD.  wallichii may act as honest indicators of body conditi...
Source: Ethology - Category: Zoology Authors: Tags: RESEARCH PAPER Source Type: research