Natural Selection

Artificial Selection

• Humans choose which plants or animals reproduce to bring out desired / specific traits

• Theorized that the environment could have a similar effect on wild species

How do we get Variation

Mutations : Permanent changes in DNA

• Happens continuously and spontaineously

• Can cause a cell to die, malfunction, multiply more than it should, have no effect, or be advantageous

• Somatic cells mutations → not passed

• Germline mutation → passed on

Adaptation (Advantageous variation)

Adaptation : Structure, behavior or physiological process that helps an organism survive and reproduce in a particular environment

• Organisms overcome environmental challenges in order to survive

  → Severe weather, famine, competition for food / space / mates

• If they don’t succeed, traits can’t be passed on

Survival of the fittest

Natural Selection : Individuals with adaptations survive and reproduce

• “Fitness” of an individual to survive and reproduce in it’s environment

Porcupine/Hedgehog Natural Selection

Structural Adaptations :

• Sharp quills for protection from predators

• Protruding snouts

• Sharp claws for digging / burrowing

Behavioral Adaptations

• Curls into ball when threatened

• Digs burrows for nests

• May hibernate during winter

Physiological Adaptations

• Ears sensitive to low frequencies

• Well developed olfactory system

• Tongue can stiffen and penetrate soil due to blood flow