Meeting Abstract
Male sexually-selected weapons are often useful in achieving mating opportunities, via success in male-male competitive contests. For this reason, the loss of a weapon should decrease male mate acquisition. Yet some species possess weapons that can be autotomized, without regeneration, to escape immediate danger. We address whether and to what extent the loss of a weapon during development affects another important trait, the testes. Theory suggests that a trade-off between weapons and testes should exist. For this reason, males that have autotomized weapons during development should invest more in testes, but this hypothesis remains untested. We tested this hypothesis using the leaf-footed cactus bug, Narnia femorata, which naturally can drop its hind limb weapons. We measured testes mass for males that dropped a hind limb during development relative to three control treatments. Males that dropped a hind limb grew significantly larger testes than the control treatments. We found that females paired with males with larger testes produced more eggs, suggesting that such investment may enhance male fitness. Our results are the first to show that males may naturally compensate for losing a weapon by investing more in a post-copulatory sexually-selected organ and that this compensation is likely to lead to more productive matings.
