A historical example of Natural Selection...
These finches are considered to be the world’s fastest-evolving vertebrates because their appearance and behavior quickly adapted to this closed and rapidly changing environment.
Because the Galapagos are a set of islands:
- Terrestrial species on these islands won’t have many relatives nearby.
- Neighbouring islands will have close relatives
- New terrestrial species won’t arrive on these islands from the South American mainland very often.
- Most of the island species have had abundant time to differentiate from their nearest living relatives.
All these factors combine to illustrate that there is very limited gene flow between the islands and the mainland, encouraging divergent evolution in the process of Natural Selection.
So what is natural Selection? Watch the Video below...
The Galápagos finches provide an excellent example of this process. Among the birds that ended up in arid environments, the ones with beaks better suited for eating cactus got more food. As a result, they were in better condition to mate. Much the same, those with beak shapes that were better suited to getting nectar from flowers or eating hard seeds in other environments were at an advantage there. IIlustrating the process that came to be known as Natural Selection.
The diagram below illusrates how environmental changes influence some Finch populations.
Today we use the term adaptive radiation to refer to this sort of branching evolution in which different populations of a species become reproductively isolated from each other by adapting to different ecological niches and eventually become separate species, just as the Finches have.
The adaptation has led to a large variety of Finches..
The Galápagos finches serve as a fascinating example of natural selection in action, by evolving according to the food available to them, the Finches illlustrate the Theory of Natural Selection. As Darwin himself said...