Costs of weaponry: Unarmed males sire more offspring than armed males in a male-dimorphic mite.

Morphological structures used as weapons in male-male competition are not only costly to develop but are also probably costly to maintain during adulthood. Therefore, having weapons could reduce the energy available for other fitness-enhancing actions, such as post-copulatory investment. We tested the hypothesis that armed males make lower post-copulatory investments than unarmed males, and that this difference will be most pronounced under food-limited conditions.