Suppose a large apartment complex is infested with cockroaches that have never been exposed to glucose-baited poison. a new tenant moves in and unknowingly brings along some stowaway glucose-averse cockroaches from her heavily-treated former apartment. these individuals escape the moving boxes and start reproducing in their new home, where they have to compete with the current resident cockroaches.

The success of the glucose-averse cockroaches in their new environment depends on the future use of glucose-baited poison in the apartment. If glucose-baited poison is not used, it is likely that the resident cockroaches will outcompete the new cockroaches, as the resident cockroaches will not exclude glucose-containing foods from their diet. However, the use of glucose-containing poison in the apartment will provide the new cockroaches a distinct selective advantage, as they will survive to reproduce, whereas the majority of the resident cockroaches will die.