Figure 1

The Midas cichlid species complex in Nicaragua. (A) The three described species of the Midas cichlid species complex. A. citrinellus is present in all lakes whereas A. zaliosus, the arrow cichlid, is the result of sympatric speciation in Lake Apoyo and remains confined to it. A. labiatus, the red-devil cichlid is found only in the great lakes and was excluded from this study because there is no evidence that it has participated in the colonization of crater lakes. (B) The four lakes of this study are found in western Nicaragua. Lakes Apoyo, Masaya, and Xiloa are all the result of volcanic processes that have left disconnected craters in which these lakes have formed.