How to use OBS. In “Environment 1” (a) and “Environment 2” (b), users select the number of oases (rich or poor), enter values for the three parameters (population size, generation time, mutation rate) and then click “start” to begin the simulation. In this figure, a represents an oasis-poor environment, and b an oasis-rich environment, with the graph illustrating how the sizes of the forewing and hindwing and the flight distance change through 30 generations. Users can click on an individual to select it for copulation in its environment, and the individual will be surrounded by a square (a, b); then the selected individuals are displayed on the crossing experiment tab (c, d). In this tab, after clicking the “cross” button, users can observe whether the two individuals can copulate. If they can, an animation indicating successful copulation and their offspring is displayed (c). If they cannot copulate, the animation shows unsuccessful copulation in that they approach each other and try to copulate, but separate immediately (d). Although we used the Japanese version of OBS for the student experiment, this figure depicts the English version. Users can easily select their language (English or Japanese) on the “language tab” at the top of the OBS window.