The Evolution of Populations

1) What is population genetics?

It is an area of Biology that is keeping track of changes in populations over time > study of genetic variation in populations.

2) What are the conditions under which allelic frequencies (p & q) remain constant from one generation to the next? (Hardy-Weinberg)

- no mutations

- random mating

- no natural selection

- large populations

- no gene flow (immigrations/emigrations; transfer of pollen etc.)

3) What are mutations? Briefly explain both point and chromosomal mutations!

Mutations are the only source of new genes and new alleles.

Point mutations - changes in the base in a gene (impact on phenotype)

Chromosomal mutations - delete, disrupt, duplicate many loci at once (almost certain to be harmful)

Facts:

- Chromosomal mutations delete, disrupt, duplicate or rearrange many loci at once.

- Crossing over occurs during prophase I (meiosis).

- The greater the number of fixed alleles, the lower the species' diversity.

- Modern synthesis looks at the genetic basis of variation and natural selection.

- Natural selection acts more directly on the phenotype and indirectly on the genotype.

Summary:

Hardy-Weinberg stated that under certain conditions (listed in q 2), the gene frequency of a population does not change from generation to generation. The population model described that gene frequencies will not change from one generation to the next even if there are more recessive alleles.

Alteration of genetic frequencies can happen because of natural selection, genetic drift, and gene flow.

natural selection is the only mechanism that constantly causes adaptive evolution.

Extra:

Hardy Weinberg principle example video