population genetics
Download
Skip this Video
Download Presentation
Population Genetics

Loading in 2 Seconds...

play fullscreen
1 / 15

Population Genetics - PowerPoint PPT Presentation


  • 70 Views
  • Uploaded on

Population Genetics. Population Genetics:. The study of allele frequencies within a population. Changes in allele frequencies are caused by the following: Natural Selection Genetic Drift Mutation Gene Flow. Natural Selection.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Population Genetics' - trisha


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
population genetics1
Population Genetics:
  • The study of allele frequencies within a population.
  • Changes in allele frequencies are caused by the following:
    • Natural Selection
    • Genetic Drift
    • Mutation
    • Gene Flow
natural selection
Natural Selection

A process whereby creatures with good traits survive and reproduce and where creatures with negative traits, die off.

genetic drift
Genetic Drift
  • Changes in allele frequencies due to the fact that alleles in offspring are a random sample of those in parents.
  • Not a result of which traits are beneficial, genetic drift is random.
causes of mutation
Causes of Mutation

Spontaneous

Radiation

Chemicals/pollution

Crossing over during meiosis

Meiosis makes sperm and egg

gene flow
Gene Flow
  • Transfer of alleles from one population to another.
  • Caused by the migration of organisms
genetics
Genetics
  • Let’s say “B” = Brown and “bb” = white.
  • Geneticists can predict babies
  • Bb x bb = 50% Brown and 50% White
genetics1
Genetics
  • Let’s say “B” = Brown and “bb” = white.
  • Let’s say that 4% of a population is white.
  • Geneticists can now predict for the population

4% = 0.04

“bb”= 0.04

“b” x “b” = 0.04

The square root of 0.04 = 0.2

“b” = 0.2

Therefore “b” = 20% of all alleles

B

b

= 0.2

4% of the population

B

BB

Bb

4%

b

= 0.2

bB

bb

genetics2
Genetics
  • If “b” = 20% of all alleles, then…
  • “B” must equal 80%.

B = 0.8

b = 0.2

4% of the population

B = 0.8

BB

Bb

4%

b = 0.2

bB

bb

slide10

What percent of the bunny population will be homozygous dominant?

B = 0.8

b = 0.2

64%

16%

B = 0.8

BB

Bb

16%

4%

b = 0.2

4% of the population

bB

bb

64% will be BB.

32% will be hybrids

slide11

A new recessive mutation has resulted in 9% of the USA becoming vampires. What percent of the population will be carriers?

N = 0.7

n = 0.3

49%

21%

N = 0.7

21%

9%

n = 0.3

42% will be carriers.

slide12

“b” = 0.6. Do the rest.

B = 0.4

b = 0.6

16%

24%

B = 0.4

24%

36%

b = 0.6

What are the percentages of the different genotypes? Fill out the punnett.

slide13

No mutation: no allelic changes occur.

No gene flow: Animals do not enter or leave the population.

Random mating: individuals pair by chance and not according to the genotypes or phenotypes.

Large population: the population is large so changes in allele frequencies due to chance are insignificant. Large populations decrease chances of genetic drift.

No selection: All genotypes are healthy and there is no selective force that favors one genotype over another.

slide14

Within a population of moths, the color dark (D) is dominant over the color white (d). Before the industrial revolution, nearly 81% of all moths were white. What percentage of the population was DD before the environment was polluted?

D = 0.1

d = 0.9

1%

9%

D = 0.1

dd

9%

81%

D _

d = 0.9

1% of the butterflies will be DD.

slide15

Mutations occur

Gene Flow. Animals enter or leave the population, thereby introducing or eliminating alleles.

Non-random mating. Animals breed according to phenotypes or genotypes.

Small population

Selection. One genotype is selected over another.

Which moth was selected for during the industrial revolution?

ad