Mutations + Migration Flashcards
How does migration cause genetic change?
Immigration is the process of an individual(s) moving to
another region with the intent of residing
Emigration is the process of leaving a place of residence with the intent of living in another region
Through migration new alleles are introduced to
populations, promoting genetic variation and changing allele frequency
Because genes are moving between populations migration is also known as ‘gene flow’
How does mutation cause genetic change?
A mutation is a permanent change in the nucleotide sequence in a gene
Mutations are important as they are the only way of creating new alleles and increasing variation
For mutations to be passed onto the offspring they must occur in the gametes - this ensures they become part of the offspring’s genetic makeup and enter the gene pool.
If the mutation is beneficial it will become part of the gene pool, if it is harmful it will be selected against by natural selection
if the mutation is beneficial it will also be the favoured allele and increase in frequency
How does genetic drift cause genetic change?
What are two examples of genetic drift?
Genetic drift is the change in allele frequencies in populations due to chance (not selection)
It is caused by not all individuals having a chance to contribute their genes to the population
-Genetic drift can lead to loss of alleles in the gene pool
- Genetic drift is most likely to have an effect in small populations where there is more inbreeding
- Alleles can become lost from the gene pool (0% allele frequency) or fixed as the only allele in the gene pool (100% allele frequency)
-Genetic drift often happens to smaller populations that have been isolated from a larger population, such as island colonists coming from the mainland
Two examples of genetic drift are The Founder Effect and The Bottleneck Effect
What is the founder effect and bottle neck effect?
The founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.
The bottleneck effect is when the size of a population is severely reduced under extreme circumstances events like natural disasters (earthquakes, floods, fires) can decimate a population, killing most individuals and leaving behind a small, random assortment of survivors.
