1. A population shares a common gene pool.

2. Genetic Variation- variety of genes.
increases the chance that some individuals will survive.
leads to phenotypic variation.
Gene pool- all alleles in a population
* Phenotypic variation is necessary for natural selection *

3. Allele frequencies measure genetic variation.
measures how common an allele is in a population
can be calculated for each allele in gene pool

4. How do populations become varied?

5. Mutation is a random change in the DNA of a gene.
can form a new allele
can be passed on to offspring if in reproductive cells

6. Recombination forms new combinations of alleles.
usually occurs during meiosis
parents’ alleles arranged in new ways in gametes

7. Hybridization is the crossing of two different species.
occurs when individuals can’t find mate of own species