Natural and Artificial

Selection

James McCarthy

Natural selection is the process by which traits that help and organism to survive are passed down to future generations to

better the survival of the species over time.

Natural Selection

http://science.howstuffworks.com/evolution/natural-selection.htm

How Natural Selection works

• Variation in traits and overproduction

• There is a differential survival reproduction/survival (fitness)

• There is heredity

• Over time this causes evolution and adaptation (Berkeley)

Variation in traits and overproduction

• Overproduction is when a species produces more offspring than resources will allow to survive. (Learner.)

•All of these offspring have different traits.

•These offspring are forced to compete with one another for limited resources.

Differential Reproduction/Fitness

• Selective pressures include predators, food, and antibiotics (drugs and toxins).

•Organisms also compete over mates. The fitter (sexier) individuals have an easier time finding a mate and therefore produce more offspring. (Berkeley)

•Fitter individuals also survive longer to produce more offspring than those with shorter life-spans.

http://www.answersingenesis.org/assets/images/articles/nab/h-pylori.jpg

Heredity

• Because there are more fit individuals reproducing than unfit individuals, the next generation of the species will carry more beneficial traits then the one before it.

• This process continues over time…

Evolution and Adaptation

•Until after many generations the species as a whole has been altered!!! Evolution has occurred!

http://daily.swarthmore.edu/static/uploads/by_date/2009/02/19/evolution.jpg

Origins

• Charles Darwin is the father of evolution and natural selection.

• In 1859, Darwin publicized his theories of evolution and adaptation. (Lucidcafe)

• He also introduced the concept of artificial selection. (Thinkquest)

http://content.artofmanliness.com/uploads/2008/11/charles_darwin_l.jpg

Artificial Selection

• Artificial selection is all around us!

• Humans domesticate many species so that dominant or favorable traits are passed on.

• Cultures have used artificial selection for harvesting crops for centuries.

• However, artificial selection has become very popular in recent years due to advances in technology and drugs. (Berkeley)

http://evolution.berkeley.edu/evosite/evo101/images/mustardselection.jpg

Natural Selection

in a nutshell!

http://evolution.berkeley.edu/evolibrary/images/interviews/naturalselection1.gif

Works Cited

• "Artificial Selection." Oracle ThinkQuest Library. ThinkQuest. Web. 25 Sept. 2009. <http://library.thinkquest.org/C0118084/Gene/Genetic_variation/artificialselection.htm>.

•"Natural selection." Understanding Evolution. UC Berkeley. Web. 24 Sept. 2009. <http://evolution.berkeley.edu/evolibrary/article/evo_25>.

• "Life Science | Session 5." Teacher Professional Development and Teacher Resources by Annenberg Media. Web. 25 Sept. 2009. <http://www.learner.org/courses/essential/life/session5/closer1.html>.

• "Lines of Evidence: Artificial Selection." Understanding Evolution. Web. 25 Sept. 2009. <http://evolution.berkeley.edu/evosite/lines/IVAartselection.shtml>.

• "Charles Darwin | Naturalist." Lucidcafé Interactive Café and Information Resource. Web. 25 Sept. 2009. <http://www.lucidcafe.com/library/96feb/darwin.html>.