9C: Genetic Drift and Gene Flow Flashcards
Genetic Drift:
a random event that dramatically alters a population’s gene pool
- Reduces genetic diversity in a population through the random removal of alleles from the gene pool - Smaller populations are more susceptible
Types of Genetic Drift: Bottleneck Effect:
the reduction in genetic diversity that occurs when a large proportion of a population is removed due to a chance event
- They can dramatically reduce a population size and therefore allele frequencies
Types of Genetic Drift: Founder Effect
Founder Effect: the reduction in genetic diversity that occurs when a population is derived from a small unrepresentative sample of the original population
- E.g. If 10 green beetles left the original multicolored population to form a new one, it would not mirror the initial gene pool and therefore the genetic diversity would be significantly lower than the original.
The Consequences of the Bottleneck Effect on Genetic Diversity:
Reduces genetic diversity through the removal of alleles due to random events(e.g. Natural disasters)
The Consequences of the Founder Effect on Genetic Diversity:
Reduces genetic diversity through the establishment of a new population with a small unrepresentative sample of the original population
Risks of Reductions in Genetic Diversity:
- Inbreeding: sexual reproduction between related individuals which keeps harmful alleles in the gene pool
- Lower Adaptive Potential: less of an ability for a population to adjust to new environmental selection pressures which could wipe them out due to the absence of advantageous alleles
Gene Flow:
the introduction or removal of alleles between populations through either migration or interbreeding
Immigration:
the movement into a population
- Results in the addition to alleles into a gene pool, increasing genetic diversity
Emigration:
the movement out of a population
Results in the removal of alleles from gene pool, decreasing genetic diversity
