Lake Victoria in East Africa is home to as many as 600 species of cichlid fish. Genetic data indicates that these fish originated from a small number of fish that colonized the lake from other lakes and rivers within the last 100,000 years. The females of two closely related species of these fish choose their mates by the color of the males. In one species, the back of the male is bright blue and in the other the back of the male is red. What process is the likely reason that these two species of fish evolved in this lake