Natural Selection

What is Natural Selection? Natural Selection is the process by which individuals that are better adapted to their new environment are more likely to survive and reproduce than other members of the same species.

Facts about Natural Selection Darwin and British biologist, Alfred Russel Wallace, proposed an explanation for how evolution occurs. Darwin explained his views on Natural Selection in the book The Origin of Species. Darwin identified a number of factors that affect the process of Natural Selection: Overpopulation Competition Variations

Overpopulation Most species produce far more offspring than can possibly survive. In many species, so many offspring are produced that there are not enough resources (food, water, and living space) for all of them.

Competition Since food and other resources are limited, the offspring must compete with each other to survive. Competition does not usually involve direct physical fights between members of a species. Instead, competition is usually indirect.

Variations Members of a species differ from one another in many of their traits. Variations are any difference between individuals of the same species.

Variations http://learn.genetics.utah.edu/content/variation/recipe/ http://learn.genetics.utah.edu/content/variation/sources/ http://learn.genetics.utah.edu/content/variation/artificial/

Natural Selection Some variations make certain individuals better adapted to their environment. Those individuals are more likely to survive and reproduce. When individuals reproduce, and offspring may inherit the allele (different forms of a gene) for the helpful trait. The offspring in turn, will be more likely to survive and reproduce, and thus pass on the allele to their offspring. After many generations, more members of the species will have the helpful trait. In effect, the environment has “selected” organism with helpful traits to be the parents of the next generation-hence the term Natural Selection.

Evolution thru Natural Selection Over a long period of time, natural selection can lead to evolution. Helpful variations gradually accumulate in a species, while unfavorable ones disappear.