1. KEY CONCEPT A population shares a common gene pool.

2. Genetic variation leads to phenotypic variation.
Genetic variation in a population is beneficial because it increases the chance that some individuals will survive.
Genetic variation leads to phenotypic variation.
Phenotypic variation is necessary for natural selection.

3. Ex: Trait for frogs  skin color
Genetic variation in a population is beneficial because it increases the chance that some individuals will survive.
Allele = version of a trait
Ex: Trait in our population: eye color
Alleles would be brown, blue, green
Ex: Trait for frogs  skin color
Alleles: green and brown

4. Genetic variation is stored in a population’s gene pool.
Genetic variation in a population is beneficial because it increases the chance that some individuals will survive.
Genetic variation is stored in a population’s gene pool.
made up of all alleles in a population
allele combinations form when organisms have offspring

5. Genetic variation is measured by allele frequencies.
measures how common an allele is in a population
can be calculated for each allele in gene pool

6. Genetic variation comes from several sources.
Mutation is a random change in the DNA of a gene.
can form new allele
can be passed on to offspring if in reproductive cells

7. Genetic variation comes from several sources.
Recombination forms new combinations of alleles.
usually occurs during meiosis
parents’ alleles arranged in new ways in gametes

8. Genetic variation comes from several sources.
Hybridization is the crossing of two different species.
occurs when individuals can’t find mate of own species
topic of current scientific research

9. KEY CONCEPT Natural selection is not the only mechanism through which populations evolve.

10. Gene flow is the movement of alleles between populations.
bald eagle migration
Gene flow occurs when individuals join new populations and reproduce.
(Ex: spores/seeds are spread to new areas)

11. Gene flow is the movement of alleles between populations.
Lots of gene flow results in similar neighboring populations
bald eagle migration

12. Gene flow is the movement of alleles between populations.
Limited gene flow results in an increased chance that two populations will evolve into different species.
bald eagle migration

13. Genetic drift is a change in allele frequencies due to chance.
Genetic drift causes a loss of genetic diversity.
Some alleles increase in frequency, others may become eliminated from the population
It is most common in small populations.

14. Genetic drift is a change in allele frequencies due to chance.
A population bottleneck can lead to genetic drift.
It is an event that drastically reduces population size.
The bottleneck effect is genetic drift that occurs after a bottleneck event.

15. Genetic drift is a change in allele frequencies due to chance.
A population bottleneck can lead to genetic drift.
Northern Elephant Seals
Hunted almost to extinction
~20 survived
Genetic Variation drastically reduced when compared to Southern Elephant Seals

16. The founding of a small population can lead to genetic drift.
The Founder Effect occurs when a few individuals start a new population (colonize a new area).
The founder effect is genetic drift that occurs after start of new population.

17. harmful alleles can become more common due to chance
Genetic drift has negative effects on a population.
Population loses genetic variation, and becomes less likely to have some individuals that can adapt
harmful alleles can become more common due to chance