What is Evolution?
The Evolution theory is based on the idea that all life forms on earth are related to each which gradually modified to different forms over time. It is the process by which living organisms are believed to have been developed from the ancestral forms during the earth history. There are two different scientific approaches to evolution; convergent evolution and divergent evolution.
What is Divergent Evolution?
Divergent evolution is the process by which closely related organisms evolve different traits. In contrast, convergent evolution occurs when organisms, which are not closely related, evolve similar traits like body coloration, body forms, and organs, independently of each other as a result of the need to adapt to similar ecological conditions. Divergent evolution is also defined as the process by which differences in groups of organisms are accumulated to form a new species, which usually occurs due to the diffusion of same species to different environments. The environment blocks the gene flow among these distinct populations, which leads to differentiated fixation of characteristics through natural selection and genetic drift.
In the case of divergent evolution, the similarity is just because of common origin, such as the divergence from the common structure or function has not yet completely concealed the underlying similarity. This includes homologous structures.
Homologous Structures and Divergent Evolution
When deciding how closely related are the two organisms, a comparative anatomist looks for those structures which are basically similar, even though they serve different functions in adults. These structures are called homologous structures and they share a common ancestor.
When a homologous structure which is specialized to perform different functions to adapt to different environmental conditions or modes of life, is shared by a group of organisms, it is called the adaptive radiation. The gradual disperse of organisms with adaptive radiation is known as divergent evolution.
Divergent species arise as the direct consequence of adaptive radiation. These species arise when some members of the species are separated from other members by a barrier (like flood, deserts or mountain range). Once separated, the species begin to adapt to the new environmental changes. After continual evolution of many generations, the population finally becomes two different species to such an extent that it becomes impossible for them to interbreed with each other.
The evolution of Darwin’s finches is a good example of divergent evolution. These are a group of 15 species of passerine birds that live on the Galapagos Island. Each of the 15 species is adapted to a different diet. This adaptation causes different beak shapes and sizes. All of these species are evolved from a common ancestor. Every time an ancestral species diverges into two or more species, this process is called speciation. Divergent evolution is the key to speciation.