BUTTERFLY EYESPOTS - THE GENETICS AND DEVELOPMENT OF THE COLOR RINGS

The butterfly Bicyclus anynana has a series of distal eyespots on its wings. Each eyespot is composed of a white pupil, a black disc, and a gold outer ring. We applied artificial selection to the large dorsal e yespot on the forewing to produce a line with the gold ring reduced or absent (BLACK) and another line with a reduced black disc and a broad gold ring (GOLD). High heritabilities, coupled with a rapid response to selection, produced two lines of butterflies with very different ph enotypes. Other eyespots showed a correlated change in the proportion of their color rings. Surgical experiments were: performed on pupal wi ngs from the different lines at the time of eyespot pattern specificat ion. They showed that the additive genetic variance for this trait was in the response of the wing epidermis to signaling from the organizin g cells at the eyespot center (the focus). This response was found to vary across different regions of the wing and also between the sexes. The particular eyespot color composition found for each sex, as well a s the maintenance of the high genetic variation, are discussed with re ference to the ecology of the butterfly, sexual selection, and visual selection by predators.