Population statistical methods

POPULATION

INTRODUCTION
Population genetics is the study of change in the frequencies of allele and genotype within a population.
Population geneticists study the genetic structure of populations, and how they change geographically and over time.

Gene – a discrete unit of hereditary information consisting of a specific sequence of DNA
Alleles – alternative forms f a gene
Genotype – the genetic makeup of an organism
Phenotype – the physical traits of an organism

HARDY WEINBERG PRINCIPAL
Under certain condition, allelic frequencies remain constant from generation to generation.
If any one condition is not made, genetic equilibrium will be disturbed and the population may evolve.

Why allele frequencies change
Five evolutionary forces can significantly alter the allele frequencies of a population
Mutation
Migration
Genetic drift
Non-random mating
Selection

mutation
Errors n DNA replication result in mutation.
Mutation can also be caused by mutagens.
It is the ultimate source of new variation n a population.

migration
Movement of individuals from one place to another.
There are 2 toes of migration :
Immigration : movement into a population
Emigration : movement out of a population

Genetic drift
Founder effect
Small group of individuals establishes a population in a new location.
Bottleneck effect
A sudden decrease in population size due to natural forces

Non-random mating
Mating that occurs more or less frequently than expected
Inbreeding
Mating with relatives
Increases homozygosity
Outbreeding
Mating with non-relatives
Increases heterozygosity

selection
Natural selection
- Environment selects for adapted characteristics
Artificial selection
- Breeder selects for desired characters

TYPES OF POPULATION STATISTICAL METHODS

DECRIPTIVE METHODES

INFERENTIAL METHODES