Darwin's Theory of Evolution
I. Darwin's theory of evolution emphasizes that animals and plants undergo a long period of evolution due to environmental changes before forming new species. However, some people have proposed that species can also evolve in a short period of time. There is a type of fish; when placed downstream where there are many predators, these fish reproduce faster. The baby fish are larger than before but of poorer quality with more deformities, which prevents overpopulation. Moreover, they grow faster. When placed upstream with fewer predators, their reproduction rate slows down, the baby fish are smaller, and their growth rate is slower.