Patterns of Evolution

1 Divergent Evolution and Adaptive Radiation

Divergent evolution occurs when an ancestral species diverges into two or more species that eventually occupy different niches. When many new species are formed which occupy different niches it is called adaptive radiation.

The diversification of animals is a very good example of divergent evolution and adaptive radiation. The reason so many different species evolved was because the dominant species of the time - that is the dinosaurs - became extinct about 65 mya and many new 'vacant' niches opened up.

Analogous structures are evidence for this type of evolution. This differs to divergent evolution as there is no recent common ancestor. Each adaptation has evolved to fit the same job or niche requirement.

3 Co-evolution

Co-evolution is the joint change of two or more species in close interaction. Predators and their prey sometimes co-evolve; parasites and their hosts often coevolve; plant-eating animals and the plants upon which they feed also co-evolve. One example of coevolution is between plants and the animals that pollinate them.