Chapter 17: Evolution of Populations Flashcards
What is an allele?
different version of a gene
What is a gene pool?
all the alleles for each gene that are present in a population
In genetic terms, what is evolution?
change over time in relative frequency of alleles in a population
What is a polygenic trait?
trait that is controlled by more than one gene
What is a single-gene trait?
trait that is controlled by one gene
What does directional selection show?
shift of a trait in a particular direction
What does stabilizing selection show?
individuals in the center have a higher fitness level than individuals on the ends
What does disruptive selection show?
individual on the ends have a higher fitness level than those towards the center and SPECIATION
What is genetic drift?
random change in allele frequencies
What is a genetic bottleneck?
drastic decrease in the size of a population (decrease in genetic variation)
What do smaller populations decrease?
variation
What is founder effect?
type of genetic drift when a few individuals colonize an new habitat the may carry a different allele frequency from the main population
Are offshoot populations representative of the population they came from?
No
What is genetic equilibrium?
allele frequencies of a population do not change
What is the Hardy-Weinberg Principle?
allele frequencies do not change unless pressures are introduced into the population
What are the five pressures of the Hardy-Weinberg Principle?
- Sexual selection
- Small population
- Immigration/Emigration
- Mutations
- Natural selection
What is speciation?
formation of a new species from an existing
When do you know when speciation has occurred?
populations can’t interbreed and produce fertile offspring
What is the key to speciation?
reproductive isolation
What are the three ways reproductive isolation can occur?
geographic isolation, behavioral isolation, and temporal isolation
What is geographic isolation?
separation by geographic barriers
What is behavioral isolation?
separation of courtship/behaviors
What is temporal isolation?
separation of reproductive seasons
