1 / 23

Natural and Artificial Selection

Natural and Artificial Selection. Grade 11 Biology SBI3U. Adaptation. A characteristic or feature of a species that makes it well suited for survival or reproductive success in its environment. Adaptation. Explains why the cactus can be successful in the desert. Survival of the Fittest.

gregory-richard
Télécharger la présentation

Natural and Artificial Selection

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Natural and Artificial Selection Grade 11 Biology SBI3U

  2. Adaptation • A characteristic or feature of a species that makes it well suited for survival or reproductive success in its environment

  3. Adaptation • Explains why the cactus can be successful in the desert

  4. Survival of the Fittest • Herbert Spencer • This phrase has been used to describe Darwin’s theory • Is this misleading?

  5. Types of Selection • Directional Selection • Stabilizing Selection • Disruptive Selection • Sexual Selection

  6. Directional Selection • Selection that favours an increase or decrease in the value of a trait from the current population average

  7. Directional Selection

  8. Stabilizing Selecton • Selection against individuals exhibiting traits that deviate from the current population average

  9. Stabilizing Selection

  10. Disruptive Selection • Favours two or more variations of a trait that differ from the current population average

  11. Disruptive Selection

  12. A Human Example • Some populations have adapted to living at extreme heights • Able to survive despite low oxygen levels

  13. Sexual Selection • The favoring of any trait that specifically enhances the mating success of an individual

  14. Artificial Selection • A controlled, captive breeding process • Occurs in captivity rather than in the wild • Humans choose which individuals to breed that demonstrate a favorable trait

  15. The Process of Artificial Selection • 1) Choose a species that can be bred in captivity • 2) Breed a large number of individuals • 3) Choose a trait that you wish to favour • 4) Identify individuals that exhibit this trait most strongly • 5) Breed only these individuals to produce the next generation • 6) Repeat steps 4 and 5 over many generations

  16. Artificial Selection in Plants • Domestic crops are bigger and heartier than wild • Why might this be important? • Selection process takes place over thousands of years – beginnings in the Fertile Crescent

  17. The Candy Experiment • Pick your favorite flavour out of the bag

  18. The Candy Experiment • Pick your favorite flavour out of the bag • Now look at what’s left • We have selected for favorable traits in our food

  19. Artificial Selection in Animals • In animals, there are a number of features we many consider

  20. Artificial Selection in Animals • In animals, there are a number of features we many consider • Size • Muscle Mass • Fattiness • Temper

  21. Our Best Friend • Wolves were among the very first domesticated animals • What did we select for in wolves?

  22. Our Best Friend • What did we select for in wolves? • Lack of aggression towards humans • Lack of fear towards humans • Territoriality towards others • Loyalty

  23. Our Best Friends • We have selected for many traits in dogs • Size • Colour • Aggression • As a result we have many breeds today

More Related