1. ADAPTATIONS AND EVOLLUTION OF SPECIES

2. What is evolution?
The change in the genetic make-up of a species over time

3. How does evolution occur?
GRADUALISM
gradual process that goes on all the time
PUNCTUATED EQUILIBRIUM
periods of rapid change are separated by periods of little or no change
Many biologist hypothesize that major environmental changes have had tremendous impact on the formation of new species. These scientist believe that evolution occurs in spurts.

4. NATURAL SELECTION All species have genetic variation.
The environment presents many challenges
Organisms tend to produce more offspring than the environment can support - competition ( struggle for survival)
Some individuals are better suited to cope with the challenges ( survival of fittest)
Characteristics best suited to environment tend to increase in a population over time

5. INDUSTRIAL MELANISM
The darkening of an organism over time due industrial pollution
peppered moth

6. BALANCING SELECTION Selection that acts in opposite directions
Example: Malaria
The allele for sickle cell anemia affects the population in opposing ways:
(1) tends to eliminate the allele in homozygous individuals because sickle cell anemia is lethal for these individuals
(2) tends to preserve the allele because the heterozygote is resistant to malaria

7. DIRECTIONAL SELECTION
The frequency of one allele tends to move in one direction
Example:
1. Birth weight in offspring
2. Seed size

8. SPECIES FORMATION Begins with divergence
Results in reproductive isoloation
Speciation occurs

9. MECHANISM FOR REPODUCTIVE ISOLATION
Geographical isolation
Ecological isolation
Temporal isolation
Mechanical isolation
Reproductive failure

10. MICROEVOLTION LEADS TO MACROEVOLUTION