Can colour affect ecology and evolution, even within species? A recent publication of Kathryn Elmer with colleagues in University of Konstanz and the International Max Planck Research School found significant consequences of a colour dimorphism across ten populations of neotropical cichlid fishes. Named for King Midas, these Midas cichlid fishes are found in only two colour forms — all fishes start their life dark but in many species 5-20% of individuals lose their melanophores before adulthood and then become completely 'gold'. We found sympatric black- or gold-coloured individuals differed consistently in their ecology and morphology. Gold fishes were more typically ’snail-eaters’ and inhabit a lower trophic level, and this has some genetic basis.
H Kusche, KR Elmer & A Meyer, "Sympatric ecological divergence associated with a colour polymorphism” is published in the open access journal BMC Biology. doi:10.1186/s12915-015-0192-7