Hoekstra, H. E., and Trevor Price. 2004. EVOLUTION: Parallel Evolution Is in the Genes. Science 303, no. 5665: 1779–1781. doi:10.1126/science.1096413.
Complex plumage patterns seem to have evolved independently among many very different bird species, a striking example of parallel evolution. In their Perspective, Hoekstra and Price discuss the molecular basis for similar dark plumage patterns between two very different arctic bird species ( Mundy et al.).