2. What evolution is not Organisms become better
Man represents the apex in evolution
Humans descended from apes
Only a theory
Only the strongest survive
It has an end purpose in mind

3. 1. Species produce more offspring than survive
Thomas Malthus believed that there was an overproduction of young
Resources would not be able to keep up with the population growth.
Famine and misery would follow
Darwin extended Malthus’ idea to include all organisms

4. Species produce more offspring than survive
Malthus
George Wallace and C. Darwin
Believed that this was God’s way of keeping people from being lazy.
The lower class would have to “pick themselves up by their bootstraps” and compete to survive
There was no ulterior motivation or social classes in nature.
Organisms have biological desires to survive.

5. 2. Individuals of a species possess different genetic traits, which help to compete for limited resources
The different traits do not lead to perfection.
They have to be good enough to get by.
Look around, no one is perfect.

6. 3. Organisms that don’t survive, don’t pass on their traits

7. 3. Advantageous adaptations will survive

8. Adaptation
Feathers=
An adaptation is a feature produced by natural selection for its current function.
it must be genetically encoded—since natural selection cannot act on traits that don’t get passed on to offspring.
the trait must actually perform that task.
it must increase the fitness of the organisms that have it
did they evolve for insulation or flight?

9. 4. Most fit organisms survive and pass on traits to offspring

10. Natural Selection Is mindless and mechanistic
Selects for whatever variation is available
Organisms do not “try”, “want” or “need” to adapt.
Is not random.
A mutation may be random,
But nature acts in a specific way.

11. Natural Selection
The change in the genetic frequency by selective pressure

12. Types of Selection
Directional selection - one trait is being favored and the other is being eliminated so the population shifts toward one trait
Stabilizing selection - range of a trait is narrowed
Disruptive selection - traits diverge toward the two extremes

13. No species lives in isolation
Ecological niche - describes either the role played by a species in a biological community or the total set of environmental factors that determine a species distribution
Generalist - has a broad niche (rat)
Specialist - has a narrow niche (panda)
Indicator species – sensitive to environmental change ( lichen)
Keystone species – provides ecosystem stability
(American alligator)
Non-native invasive species (European starling)

14. Competitive Exclusion
Gause proposed the competitive exclusion principle which states that no two species can occupy the same ecological niche at the same time. The one that is more efficient at using resources will exclude the other.
Resource partitioning - species co-exist in a habitat by utilizing different parts of a single resource. Example: Birds eat insects during the day and bats eat insects at night.

15. Resource Partitioning

16. All species live within limits
Law of limiting factors: The factor in the shortest supply relative to its demand will limit its growth
Range of Tolerance: abiotic factor (light, nutrients, moisture)
Plants: N for terrestrial, P for aquatic

17. Range of tolerance

18. Genetic Engineering Excise a gene with the desired trait
Insert the gene into the host cell’s genome
The host organism has the new trait
Bt corn

19. Factors that influence evolution
Mutations
Genetic drift
Genetic migration
Natural selection
Population size
Non-random mating