Chapter 7 - Evolution and Adaptation Flashcards
What are the two primary ways that variation arises in a population?
Mutation and genetic drift.
What kind of mutations are most likely to persist?
Positive
What is genetic drift?
A process that occurs when genetic variation is lost because of random variation in mating, mortality, fecundity and inheritance.
What size of population does genetic drift have a greater affect on?
Smaller populations
What is the bottleneck effect?
A reduction of genetic diversity in a population due to a large reduction in population size.
Does the bottleneck effect always result in diversity loss?
No, this depends upon the genetic diversity that was present in the initial population and how much of that was lost/conserved afterwards.
How can a loss of genetic diversity limit the ability of a population to adapt to future environmental changes?
Loss of genetic diversity = loss of alleles. This could include the loss of alleles that would have been beneficial for environmental changes.
What is the founder effect?
When a small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation.
What is selection?
The process by which certain phenotypes are favoured to survive and reproduce over other phenotypes.
What is stabilizing selection?
When individuals with intermediate phenotypes have higher survival and reproductive success than those with extreme phenotypes.
What is directional selection?
When individuals with an extreme phenotype experience higher fitness than the average phenotype of the population.
What is disruptive selection?
When individuals with either extreme phenotype experience higher fitness than individuals with an intermediate phenotype.
What type of selection does this graph model?
Directional selection
What type of selection is modelled in this graph?
Disruptive
What type of selection is modelled by this graph?
Stabilizing
