Lecture 33- population genetics and speciation

Population

A group of the same species living in a specific environment/area

Microevolution

The change in allelic frequencies in a population over time

Natural selection works on?

Works on individuals

Evolution works on?

Works on population

Genetic variation causes what type of variation? Based on what?

Phenotypic variation based on changes in genes/DNA sequences

What results in neutral variation?

Point mutations in introns

Sources of genetic variation are from?

• new alleles arising through mutations (changes in the DNA sequence)

• Heritable changes in germline cells, non-heritable in somatic cells

• Spontaneous mutations through errors in DNA replication

• Induced mutations through exposure to mutagens

• Sexual reproduction during crossing over, independent assortment and random fertilization

Where did human globin genes evolve from?

Duplication events

What does a mutation in diverged globin genes result in?

Resulted in 2 different functioning genes on 2 different chromosomes

What does the Gene pool consist of ?

Consists of all copies of every type of allele at every locus in all members of a population

When do fixed alleles occur

When there is only one allele for a particular locus in a population

What happens to allele and genotype frequencies when the population is not evolving?

Frequencies remain constant from generation to generation

What is the allele frequency of the population if it remains constant?

(80%) and (20%)

What is needed for the Hardy Weinberg equilibrium

-no mutations

-random mating

No natural selection

Extremely large population size

No gene flow

In a population of peacocks, a peen selectively chooses a people based on shiny and large his feathers are. Which assumption of hardy Weinberg does this violate?

Random mating

Genetic drift

Ex/ flip a coin 1000 times, around 50/50, flip a coin 10 times, around 70/30, this happens with a small number of individuals

Bottle neck effect

An example of genetic drift; a sudden change in the environment randomly kills a large number of individuals (and the alleles that they carry)

Can drastically alter the allele frequency in the remaining population

What do bottlenecks always reduce?

The allele variability in the surviving population

Founder effect

Example of genetic drift when a group of individuals (and alleles that they carry) move to a new area and form a new population

Genetic drift is significant in what populations?

Smaller populations

Genetic drift can cause allele frequencies to change at?

At random

Genetic drift can lead to?

A loss of genetic variation within populations

Genetic drift can causes harmful alleles to become

To become fixed

Gene flow

Transfer of alleles into (immigration) or out of (emigration) population due to the movement of fertile individuals or their gametes

Natural selection

If a specific allele is beneficial, the frequency of that allele goes up in a population over generations