The Evolution of Populations Flashcards
Natural selection acts on ___, but only ___ evolve
Individuals ; populations
What is microevolution?
Change in allele frequencies in population over generations; evolution at its smallest scale
What three mechanisms could cause allele frequency to beneficially changes?
- Natural selection (adaption to the environment)
- Genetic drift (chance events alter allele frequencies)
- Gene flow (transfer of alleles between populations
New combinations of existing alleles occur through what three mechanisms?
- Crossing over
- Independent assortment
- Fertilization
What is crossing over?
Exchange of genetic material between homologous chromosomes during meiosis
What is independent assortment?
Random distribution of chromosomes into gametes during meiosis
What is fertilization?
Random combination of gametes
What is a population?
A group of individuals of the same species that live in the same area and interbreed
What does the gene pool consist of?
All copies of every allele at every locus in all members of the population
When is a locus fixed?
If all individuals in a population are homozygous for the same allele
What does the Hardy-Weinberg equation do?
Describes the expected genetic makeup for a population that is not evolving at a particular locus
What are the conditions for Hardy-Weinberg Equilibrium?
- No mutations
- Random mating
- No natural selection
- Extremely large population size
- No gene flow
Regarding genetic drift, the ___ the sample, the ___ the chance of random deviation from a predicted result
Smaller ; greater
What is the founder effect?
When a few individuals become isolated from a larger population (Ex. genetic drift could occur if a few butterflies were blown to a new island)
What is the bottleneck effect?
When there is a drastic reduction in a population size due to a sudden change in the environment, leading the gene pool to no longer be reflective of the original populations gene pool
