Natural selection 150 years on : Article : Nature

Natural selection 150 years on : Article : Nature

But can speciation be observed? Yes. Field biologists have witnessed speciation in action among several plant, amphibian, bird and fish species18. What matters for Darwin's theory is that the process by which populations of interbreeding individuals split into two non-interbreeding populations follows straightforward routes of natural selection. One good example is that females of a cichlid fish species vary genetically in their preferences for males of red and blue colours. Biologists are witnessing red males occupying the lower depths of Lake Victoria, in Africa, and females with matching preferences are following them. These mating preferences are causing this single species to split into two19.