Explain how competition between two species leads to character displacement and ecological exclusion by giving an example.
Character displacement is evolutionary divergence that occurs when two similar species inhabit the same environment. In this case natural selection favors those organisms, which develop modifications reducing their competitive pressure for resources and therefore increasing their chance for survival. This phenomenon was also studied on the example of two species of Galapagos finches (Geospiza fuliginosa and Geospiza fortis). In this case character displacement arises from the competition for seeds. Both of them are seed eaters. When they occur together, they compete for medium-sized seeds. This reduces the effective abundance of that resource for both species. Therefore, this creates an evolutionary pressure on both species that tends to enhance the differences in beak size over time.