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GENETIC EVOLUTION. Gene Pool All genetic information from a population of a specific species.

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Presentation on theme: "GENETIC EVOLUTION. Gene Pool All genetic information from a population of a specific species."— Presentation transcript:

1 GENETIC EVOLUTION

2 Gene Pool All genetic information from a population of a specific species

3 Relative Frequency The number of times an allele occurs in gene pool, compared to other alleles in same gene pool

4 Relative Frequency The number of times an allele occurs in gene pool, compared to other alleles in same gene pool What is the frequency Of black fur?

5 Relative Frequency The number of times an allele occurs in gene pool, compared to other alleles in same gene pool What is the frequency Of black fur? - 20/50

6 Relative Frequency The number of times an allele occurs in gene pool, compared to other alleles in same gene pool What is the frequency Of black fur? - 20/50 - 2/5

7 Single-gene Trait A single-gene trait is controlled by one gene that has two alleles. Variation in this gene leads to only two possible phenotypes Example: Aa, Tt, SS, nn, MM, Jj

8 Single-gene Trait A single-gene trait is controlled by one gene that has two alleles. Variation in this gene leads to only two possible phenotypes Example: Aa, Tt, SS, nn, MM, Jj In other words: You have It or you don’t have it

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10 Polygenic Traits One polygenetic trait can have many possible genotypes and phenotypes Example: Height, Skin color, eye color

11 Polygenic Traits One polygenetic trait can have many possible genotypes and phenotypes Example: Height, Skin color, eye color

12 In the real world Two variables control traits: - Frequency of alleles (Quantity) - Dominant or recessive

13 Directional Selection Over time, an extreme phenotype is favored over other phenotypes. This causes the curve to shift.

14 Stabilizing Selection Over time, phenotypes in the center are favored over others

15 Disruptive Selection Phenotypes at the upper and lower end of curve are favored over the middle

16 Founder Effect Allele frequencies change as a result of the migration of small populations.

17 Founder Effect Example: The Amish

18 Hardy-Weinberg Principle States that allele frequencies in a population will remain constant unless one or more factors cause it to change. Hardy-Weinberg Equation

19 Hardy-Weinberg Principle P= Frequency of Dominant Alleles q= Frequency of Recessive Alleles P + q =1

20 Hardy-Weinberg Principle P= Frequency of Dominant Alleles q= Frequency of Recessive Alleles


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