D 4.1 Natural Selection

Cell Theory

all living things are made of cells

Darwin’s exploration of evolution (7)

1. More individuals are born in a species than the environment can support. Struggle for survival

2. Within every species there is naturally variation

3. Variations of some give them an advantage over others in a struggle to survive.

4. More of these individuals will survive and reproduce than those with less favorable traits

5. Many traits are passed from parents to offspring

6. Those with more favorable traits will reproduce, so the # of individuals with favorable traits increases each generation. The number with less favorable traits decreases.

7. The favorable traits eventually becomes the most common form and over many generations

Natural Selection causes evolution

NS is the mechanism driving evolutionary change

1. NS has occurred continuously for billions of years → causing biodiversity of life on Earth

2. Evolution has been known for a long time but the mechanism was not established until Darwin

3. Dawrin’s Theory replaced Lamarksim through a paradigm shift

Paradigm Shift

Fundamental change in approach of assumptions

Overproduction of offspring and competition (C 4.1)

• when resources are limited such as food or shelter, competition increases

• Overproduction of offspring increases competition as well → leads to STRUGGLE TO SURVIVE (Natural selection)

• Different Abiotic factors can lead to struggle for survival

Variation

• variation must be present in a population

• mutation and sexual reproduction creates new alleles (version of a trait) and generates new combinations of alleles.

Fitness (D 4.1.5) Differences between individuals in adaptation

1. Different individuals have different adaptations

2. adaptations increase chance of survival

3. Increased chance of survival increases reproduction survival of the fittest