# POPULATION GENETICS What we learned from Mendelian Genetics

• Slides: 21

POPULATION GENETICS

What we learned from Mendelian Genetics? 1. Organisms defined by their genome: 2. Many phenotypes are polygenic 3. Mechanism of inheritance

Individuals are defined by their genotype. Population = Sum of its individuals.

Individuals are defined by their genotype. Population = Sum of its individuals.

Calculate population phenotype frequencies. Ex. A population with 750 red and 250 green rats (red>green).

Calculate population phenotype frequencies. Ex. A population with 640 black and 360 gray cats (black>gray).

A population is defined by its allele frequency.

2 different populations, 2 distinct allele frequencies.

A sexual orgy: random reproduction in a population.

A sexual orgy: random reproduction in a population.

Determine the phenotype frequency of the offspring generation and allele frequency of the parents.

Ex. What is the allele frequency of parent rat population when there are 36 green and 64 red pups (red>green).

Ex. What is the allele frequency of a population of 25 purple and 75 yellow parrots (yellow>purple).

In cats the allele frequency of short hair is 0. 6 and of long hair is 0. 4. How many individuals of the next generation have short hair in a population of 100? (Short>long).

In cats the allele frequency of short hair is 0. 6 and of long hair is 0. 4. How many individuals of the next generation have short hair in a population of 100? (Short>long).

Calculate the allele frequency of the NEXT generation from the allele frequency of the previous generation.

Calculate the allele frequency of the NEXT generation from the allele frequency of the previous generation.

Calculate the allele frequency of the NEXT generation from the allele frequency of the previous generation.

Calculate the allele frequency of the NEXT generation from the allele frequency of the previous generation.

Conclusion: mere sexual reproduction does not change allele frequency.

The population is in Hardy-Weinberg equilibrium.