Topic 7 Flashcards
What is a change in allele frequencies in populations over generations?
Microevolution
A _ is the combination of two alleles.
Gene
The term for all the alleles present in all individuals in the population is:
Gene pool
New genes and alleles arise by:
i) mutation
ii) gene duplication
T/F: Mutations occur randomly and create new alleles
True
What is something that can shuffle existing alleles into new combinations?
Sexual reproduction
What are three major factors that alter allele frequencies and bring the most evolutionary changes?
i) Natural selection
ii) Genetic drift
iii) Gene flow
What is directional selection?
It is natural selection that favours individuals at one end of the phenotypic range (one extreme phenotype)
What is disruptive selection?
It is natural selection that favours individuals at both extremes of the phenotypic range
What is stabilizing selection?
It is natural selection that favours intermediate or common (median) phenotypes
Is variance larger in disruptive selection or stabilizing selection?
Disruptive selection since there are two extremes that allow for variation whereas in stabilizing there is one median phenotype that is passed on
What is genetic drift?
Random changes in allele frequency in a population (regardless of natural selection)
Is genetic drift more likely in small or large populations?
Small (greater chance of deviation)
T/F: Rare alleles are more likely to be lost due to genetic drift
True
T/F: Genetic drift increases genetic variation in a population
False (decreases)
T/F: Genetic drift causes evolutionary changes and creates adaptations
False (does not create adaptations)
What effect is a sudden reduction in population size due to a change in the environment?
Bottleneck Effect
What is the effect of the Bottleneck Effect?
Allele frequency in the next generation is different than the previous generation because there are only a few individuals that contribute to the next generation
T/F: The bottleneck effect increases genetic variation in the surviving populations.
False (reduces)
What effect occurs when a few individuals become isolated from a larger population?
Founder Effect
What is the effect of the Founder Effect?
The small founding population has a small fraction of the total genetic variation present in the original population
What is the movement of alleles between populations?
Gene flow
What is an example of gene flow?
Ex. interbreeding, migration, pollen, etc
T/F: Gene flow introduces new variation into the receiving population
True
