Genetic Change Flashcards
Evolution
Change in population over time.
population evolves, not individuals
Artificial selection
When humans select particular individuals from a population based on a certain characteristic.
Mutation
Is a permanent chcnagein the base sequence of Dna that results in new alleles..
Harmful, Silent, Beneficial.
Genetic drift
(smaller population)
Practice
The frequency of alleles can change due to chance rather than by selection pressure.
Alleles fixed or lost.
Bottleneck effect
Practice
Populations reduced to a low number due to human action or catastrophic events (hunting, new predators etc).
Examples of genetic drift
Founder effect
A small number of individuals migrate or isolate from the original population decreasing genetic diversity.
Examples of genetic drift
Natural selection
Beneficial phenotypes in a population tend to be preserved and have reproductive success, while unfavourable phenotypes tend to be lost (reducing reproductive success).
Gene flow (migration)
Genes are exchanged with other gene pools as individuals move (migrate) between them.
immigration
emigration
Non-random mating
Individuals seeking a particular phenotype in an individual to mate with.
Directional Selection
Selective pressures select against one extreme of the trait.
The population trait distribution shifts toward the other extreme.
Stabilizing Selection
Selective pressures select against the two extremes of a trait.
The median phenotypes are retained + become more common.
Disruptive Selection
Selection pressures act against individuals in the middle of the trait.
Results in two extremes on the curve.
Genetic diversity
The total number of genetic characteristics in a population.
Allele frequency
The amount of an allele in a population.
Immigration
Movement of an individual into a population.
