1. I. Natural Selection
Who Lives
Who Dies

2. A. Darwin Proposed 2 Things
Evolution occurs
Evolution occurs due to Natural Selection

3. Who do you think chooses who sticks around and who doesn’t?
The Environment

4. The environment chooses which organisms will survive and reproduce based on their phenotype
                                                                

5. Steps to Natural Selection

6. Variation is the raw material for natural selection
a. Within a population there is a variation in traits (phenotypes)

7. Living things face a constant struggle for existence
a. Produce more offspring than there is room and food for, so they must compete to survive

11. Only some individuals survive and reproduce
a. Some individuals are more “fit” for the environment or for life in general
ex. Resistance to disease

13. 4. Natural selection causes genetic change

14. a. Each generation consists of individuals with traits(phenotypes) that made them more “fit”, so over time, alleles for those traits will increase in frequency

15. Species adapt to their environment
a. selection tends to make organisms better suited to their environment

16. C. Lethal genes are kept in the gene pool if in the heterozygous form because those individuals will not show the lethal phenotype