Convergence, Natural Selection, 'Survival of the Fittest'

    Organisms can evolve in many different ways. As such, different species can evolve similar traits to related or unrelated species. During divergent evolution, related species will evolve similar traits- these traits are known as homologous. In contrast, convergent evolution occurs when organisms that are not closely related evolve similar traits. Traits that evolve through convergent evolution are analogous. Convergent evolution can occur due to similar selective pressures that unrelated species face, through random mutations, or to adapt to their ecological niche. 

    One example of convergent evolution is the evolution of caffeine in coffee, tea, and cacao plants. These plants are in separate branches in an evolutionary tree and are not closely related at all. Although these plants are not on the same branches of an evolutionary tree, they all produce caffeine. Through examining the genomes of coffee, tea, and cacao plants, evolutionary biologists discovered that the enzymes that produce caffeine are different across these plants. This indicates that, through convergent evolution, each of these plants independently evolved the ability to produce caffeine. All of these plants likely evolved the ability to produce caffeine as a defense mechanism as caffeine is a natural pesticide and protects these plants from insects.