Types of selection

Types of Selection

By: Nikhil, Madeleine, Angela

Overview1. Review of natural selection

2. What is stabilizing selection?

3. How does stabilizing selection work?

4. Examples of stabilizing selection

5. What is directional selection?

6. Reasons for directional selection

7. Examples of directional selection

8. What is disruptive selection?

9. Causes of disruptive selection

10.Examples of disruptive selection

1. Variation [3]

2. Inheritance [3]

3. High rate of population growth [3]

4. Differential survival and reproduction [3]

Process of Natural Selection:

What is Stabilizing

Selection?

Stabilizing Selection

• commonly uses negative/ purifying selection [1]

Optimizing selection [4]

Normalizing selection [4]

Am-bidirectional selection [1]

•prevent divergence of form & function [2]

• visible polygenic characters/traits [2] [4]

• results in differential reproduction [4]

How does it Work?

Graphs

Example #1: Human Birth Weight

Example #2:Siberian Huskies

What is Directional

Selection?

Directional Selection

Directional selection is a type of natural selection where it

favors one phenotype over the other mean or extreme

phenotypes.[7]

Reasons for Directional

Selection

Environments

that have

changed over

time or when

animals

migrated to

new areas[8]

Climate

European Black

Bears

Food Availability

Galapagos Finches

HUMAN IMPACT

Greyhound Dogs

What is Disruptive

Selection?

Disruptive Selection

•favours genes that give more advantages for survival [9]

Causes

human destruction [10]

environmental pollution [10]

oClam size – small and large clams are favoured over medium sized clams [11]

Example:

Recap !

Thank you for listening !

Bibliography1. "Stabilizing selection - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 16 Apr. 2012. <http://en.wikipedia.org/wiki/Stabilizing_selection>.2. "Types of Natural Selection - Stabilizing Selection." About.com. N.p., n.d. Web. 16 Apr. 2012. < http://evolution.about.com/od/NaturalSelection/g/Types-Of-Natural-Selection-Stabilizing-Selection.htm>.3. " Evolution and Natural Selection ." The Global Change Program at the University of Michigan. N.p., n.d. Web. 16 Apr. 2012. <http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html>.4. "Research Stabilizing Selection by | BookRags.com." BookRags.com | Study Guides, Lesson Plans, Book Summaries and more. N.p., n.d. Web. 17 Apr. 2012. <http://www.bookrags.com/research/stabilizing-selection-wog/>.5. "natural selection: stabilizing." SASindex. N.p., n.d. Web. 17 Apr. 2012. <http://www.starsandseas.com/SAS%20Evolution/SAS%20natselection/natselec_stabilizing.htm>.

6. "Stabilizing selection and a stable environment | darwinbookcats." darwinbookcats | a blog about evolution, books, and cats. N.p., n.d. Web. 17 Apr. 2012. <http://darwinbookcats.wordpress.com/2011/06/22/stabilizing-selection-and-a-stable-environment/>.7. "natural selection: directional." SASindex. N.p., n.d. Web. 18 Apr. 2012. <http://www.starsandseas.com/SAS%20Evolution/SAS%20natselection/natselec_directional.htm>.8. Scoville, Heather. "Directional Selection - Types of Natural Selection." Evolution - Natural Selection, History of Life on Earth, Darwinism, Lesson Plans and More!. N.p., n.d. Web. 18 Apr. 2012. <http://evolution.about.com/od/NaturalSelection/g/Types-Of-Natural-Selection-Directional-Selection.htm>.9. Scoville, Heather. “Disruptive Selection – Types of Natural Selection. “Evolution – Natural Selection, History of Life on Earth, Darwinism, Lesson Plans and More!. N. p., n.d. Web. 19 Apr. 2012 < http://evolution.about.com/od/NaturalSelection/g/Types-Of-Natural-Selection-Disruptive-Selection.htm>10. "natural selection: disruptive." SASindex. N.p., n.d. Web. 19 Apr. 2012. <http://www.starsandseas.com/SAS%20Evolution/SAS%20natselection/natselec_disruptive.htm>.11. definition. "Research Disruptive Selection by | BookRags.com." BookRags.com | Study Guides, Lesson Plans, Book Summaries and more. N.p., n.d. Web. 19 Apr. 2012. <http://www.bookrags.com/research/disruptive-selection-wog/>.