The evolution of male nuptial colour in a sexually dimorphic group of fishes (Percidae: Etheostomatinae).

To test hypotheses explaining variation in elaborate male colouration across closely related species groups, ancestral-state reconstructions and tests of phylogenetic signal and correlated evolution were used to examine the evolution of male body and fin colouration in a group of sexually dichromatic stream fishes known as darters (Percidae: Etheostomatinae). The presence or absence of red-orange and blue-green male colour traits were scored across six body regions in 99 darter species using a recently estimated amplified fragment length polymorphism (AFLP) phylogeny for comparative analyses. Ancestral-state reconstructions infer the most recent common ancestor of darters to lack red-orange colour and possess blue-green colour on different body regions, suggesting variation between species is due to independent gains of red-orange and losses of blue-green. Colour traits exhibit substantial phylogenetic signal and are highly correlated across body regions. Comparative analyses were repeated using an alternative phylogenetic hypothesis based on one mitochondrial and two nuclear genes, yielding similar results to analyses based on the AFLP phylogeny. Red-orange colouration in darters appears to be derived; whereas, blue-green appears to be ancestral, which suggests that different selection mechanisms may be acting on these two colour classes in darters.