1. Unit 11 7F
Analyze and evaluate the effects of other evolutionary mechanisms, including genetic drift, gene flow, mutation, and recombination.  

2. B stands for black b stands for brown
Let’s remember…
An allele is an alternative form of one gene
B stands for black b stands for brown
The allele would be…

3. Genetic Drift
An evolutionary mechanism in which allele frequencies change in a population

4. Allele frequency changes due to…
Natural disaster like flood, fire, or earthquake
A random change of the population (some are eliminated)
Different from natural selection b/c its by chance or randomly

5. R = red star r = green heart
Original Pop
Pop after change
R = red star r = green heart
6R, 5r 5r

8. Bottleneck Effect
The change in allele frequency where only genes of the surviving population members can be passed to future generations

11. Gene Pool
the sum of all the genes in an interbreeding population

12. Gene Pool
2 blue alleles
1 red allele
12 green alleles

14. Founder Effect
The change in allele frequency in a gene pool that changes from a large population to a small population
Ex: small number of individuals get separated from a larger population… the change in the allele frequency is the founder effect

16. Founder Effect

17. Gene Flow
Occurs when the genes of 1 population flow into a different population
This change causes a shift in allele frequency

18. Immigration
Alleles move INTO a population

19. Emigration
Alleles move OUT OF a population

20. Lots of gene flow…
Slows down evolution
Lots of new alleles coming into and out of a population
More genetic variation within a population
Makes 2 populations more similar

22. Lack of gene flow…
Less variation within a population
Makes 2 populations more different and separates them

24. Mutation
Any change in the genetic material of a cell
Can occur within individual genes OR
Can involve changes in piece of chromosomes

25. If the mutation is beneficial to the organism, the mutation will be passed on to offspring
Slowly over time the mutation will become more common in a population

26. Recombination
A source of heritable variation
Occurs for 2 reasons:
Independent assortment
Crossing over

27. Independent Assortment

28. Crossing Over

29. Hardy-Weinberg Principle
States that allele frequencies in a population will remain constant unless one ore more factors cause those frequencies to change

30. Hardy-Weinberg Equation
P pq + q2 = 1
Homozygous dominant
Homozygous recessive
Heterozygous
p = dominant allele frequency
q = recessive allele frequency

31. Genetic Equilibrium
The situation in which allele frequencies remain constant (don’t change)
If frequencies don’t change, the population doesn't evolve

32. Conditions required to maintain genetic equilibrium:
Random mating
Population must be large
No immigration or emigration
No mutations
No natural selection