Morph-Specific Weapon-Correlated Traits in a Male Dimorphic Stag Beetle Prosopocoilus inclinatus, (Coleoptera: Lucanidae)

Abstract

Several male beetles that fight with rival males show dimorphic weapons. Major males have large weapons and fight aggressively with rival males. Minor males have small or no weapons and often adopt an alternative reproductive tactic without fighting. Suitable body shapes are likely to differ depending on the tactic. Thus, the set of body parts that are compatible with distinct weapons may be different in major and minor males according to their battle tactics. Many studies have reported correlations between weapons and some morphological traits, but few studies have shown the difference in the correlation patterns between major and minor males. Here, we show that in a male dimorphic stag beetle, Prosopocoilus inclinatus (Motschlsky), several morph-specific traits are correlated with weapon size. Mandible size correlates positively with eye size in major males only but correlates positively with the length of forelegs and negatively with abdomen weight in minor males only. These results suggest that the correlated trait sets are different between the morphs because each morph adopts different battle tactics and mating strategies.