Reproductive interference between Callosobruchus bean beetles (#205)
In nature, distinct resource partitioning has been often observed between two closely related species. Though this phenomenon has been mostly considered as the outcome of resource competition, reproductive interference may be another driver. Then, using two Callosobruchus bean beetles, I have examined if reproductive interference causes species exclusion in a homogeneous environment, and then causes resource partitioning in a heterogeneous environment. I demonstrated that reproductive interference was a more dominant driver in the competition dynamics than resource competition. Furthermore, oviposition resource partitioning occurred in a dish when two species females were housed with two species males and two oviposition resources. As analyzing experimental results, we found that the resource partitioning was caused by reproductive interference, in which both beetle females changed their oviposition resource preferences when stayed with heterospecific males, probably in order to avoid reproductive interference. Thus, these results indicate that female escaping from reproductive interference can quickly result in resource partitioning between closely related species, even without their evolutionary adaptations to resources.