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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.

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natural and artificial selection

Natural and Artificial Selection

Grade 11 Biology SBI3U

adaptation
Adaptation
  • A characteristic or feature of a species that makes it well suited for survival or reproductive success in its environment
adaptation1
Adaptation
  • Explains why the cactus can be successful in the desert
survival of the fittest
Survival of the Fittest
  • Herbert Spencer
  • This phrase has been used to describe Darwin’s theory
  • Is this misleading?
types of selection
Types of Selection
  • Directional Selection
  • Stabilizing Selection
  • Disruptive Selection
  • Sexual Selection
directional selection
Directional Selection
  • Selection that favours an increase or decrease in the value of a trait from the current population average
stabilizing selecton
Stabilizing Selecton
  • Selection against individuals exhibiting traits that deviate from the current population average
disruptive selection
Disruptive Selection
  • Favours two or more variations of a trait that differ from the current population average
a human example
A Human Example
  • Some populations have adapted to living at extreme heights
  • Able to survive despite low oxygen levels
sexual selection
Sexual Selection
  • The favoring of any trait that specifically enhances the mating success of an individual
artificial selection
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
the process of artificial selection
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
artificial selection in plants
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
the candy experiment
The Candy Experiment
  • Pick your favorite flavour out of the bag
the candy experiment1
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
artificial selection in animals
Artificial Selection in Animals
  • In animals, there are a number of features we many consider
artificial selection in animals1
Artificial Selection in Animals
  • In animals, there are a number of features we many consider
    • Size
    • Muscle Mass
    • Fattiness
    • Temper
our best friend
Our Best Friend
  • Wolves were among the very first domesticated animals
  • What did we select for in wolves?
our best friend1
Our Best Friend
  • What did we select for in wolves?
    • Lack of aggression towards humans
    • Lack of fear towards humans
    • Territoriality towards others
    • Loyalty
our best friends
Our Best Friends
  • We have selected for many traits in dogs
    • Size
    • Colour
    • Aggression
  • As a result we have many breeds today