Guppies in the wild have evolved over at least half-a-million years — long enough for the males’ coloration to change dramatically. Yet an orange patch on the male has remained remarkably stable. Why has it remained the same hue of orange over such a long period of time? Because that is the color female guppies prefer.
Quoted from They call it ‘guppy love’: Biologists solve an evolution mystery on ScienceDaily: Top News