Experimental manipulation reveals a trade-off between weapons and testes

Theory predicts a trade-off between sexually-selected weapons used to secure mates and post-copulatory traits used to maximize fertilization success. However, individuals that have a greater capacity to acquire resources from the environment may invest more in both pre- and post-copulatory traits, and trade-offs may not be readily apparent. Here, we manipulate the phenotype of developing individuals to examine allocation trade-offs between weapons and testes in Mictis profana (Hemiptera: Coreidae), a species where the hind legs are sexually selected weapons used in contests over access to females. We experimentally prevented males from developing weapons by inducing them to autotomize their hind legs before the final molt to adulthood. We compared trait expression in this group to males where autotomy was induced in the mid legs, which are presumably not under sexual selection to the same extent. We found males without weapons invested proportionally more in testes mass than those with ...