1. How does genetic variation in a population increases the chance that some individuals will survive?

A: A population with a lot of genetic variation has a wide range of phenotypes.  Genetic variation is stored in a  population's gene pool which is the combined alleles of all individuals in a population.  When organisms mate and have offspring, different combinations occur and some might be very advantageous for the organism.

2. What are two main sources of genetic variation?

A: -Mutation - a random change in the DNA of a gene
-Recombination: new allele combinations form in offspring, mostly during meiosis.

3. What is normal distribution?

A: When frequency is high near mean value and decreases to both ends.

4. What is microevolution?

A: It is the observable change in allele frequencies of a population over time.

5. What are the tree way in which natural selection change the distribution of a trait?

A: -Directional selection - phenotype at one extreme of a trait's range is preferred.  A trait that once was rare becomes more common.

- Stabilizing selection - when intermediate phenotype is favored

- Disruptive selection - when both extreme phenotypes are favored while intermediate phenotypes are selected against by something in nature.

6. What is an example of a gene flow?

A: When individuals move between populations, it increases genetic variation of receiving population which is gene flow.  The less the gene flow, the more different two populations become.

7. Genetic drift is the change in allele frequencies due to chance.  What are two types of genetic drifts and what impacts do they have?

A: -The bottleneck effect is when the size of population is greatly reduced due to some event

- Founder effect is when a small number of individuals colonize a new area.

Genetic drift causes the population to lose genetic variation.

8. What are two types of sexual selection?

A: -Intrasexual selection - competition among males for females

- Intersexual selection - certain traits in males attract females

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