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Genes and Variation
Single-Gene Traits and Genetic Drift
Polygenic Traits
Hardy-Weinberg Equilibrium and Evolution
The Process of Speciation
100
This source of genetic variation involves a change in the sequence of DNA.
What is a mutation?
100
This is the maximum number of phenotypes a single-gene trait can have.
What are three phenotypes?
100
This is the minimum number of genes controlling a polygenic trait.
What are two genes?
100
This is the population size that will likely result in evolution because Hardy-Weinberg equilibrium will not be met.
What is a small population size?
100
This is the definition of speciation.
What is the formation of a new species?
200
This is all the genes and alleles in a population.
What is a gene pool?
200
This is what changes when natural selection acts on a single-gene trait.
What are allele frequencies?
200
This controls how many phenotypes are possible for a trait.
What does the number of genes do?
200
These describe movement of individuals to or from a population. If either happens, evolution will occur.
What are immigration and emigration?
200
This is the definition of reproductive isolation.
What happens when some members of one population stop breeding with other members of that population?
300
This is how evolution is defined in genetic terms.
What are changes in allele frequency over time?
300
This phenomenon happens when a small group of individuals migrates to a new environment and colonizes it. The resulting population may have very different allele frequencies than the original population.
What is the founder effect?
300
This type of selection happens when one extreme phenotype has a higher fitness than the rest of the phenotypes. For example, birds with the longest legs have a higher fitness. After several generations, more birds have longer and longer legs.
What is directional selection?
300
If one genotype has better fitness than another, this type of selection will occur and the species will evolve.
What is natural selection?
300
This type of isolation occurs when two populations are physically separated by rivers, mountains, and other features of the landscape.
What is geographic isolation?
400
This source of genetic variation is the reason you look different from your siblings and parents.
What is genetic recombination during sexual reproduction?
400
This phenomenon happens when most of the individuals in a large population suddenly die, leaving behind a small set of individuals. This almost always results in a loss of genetic diversity.
What is a genetic bottleneck?
400
This type of selection happens when both extremes have a higher fitness than the phenotype in the middle. For example, a species of butterfly ranges from green to yellow to orange to red. It has two strategies to avoid getting eaten: it either blends in with its environment (green wings) or stands out and warns predators that it’s poisonous (red wings). After several years have passed, most butterflies have either green wings or red wings, and almost none have yellow or orange wings.
What is disruptive selection?
400
This type of selection will result in nonrandom mating, meaning evolution could occur in a population.
What is sexual selection?
400
This is an example of behavioral isolation.
What is a change in courtship rituals preventing two populations from interbreeding?
500
This source of genetic variation describes how bacteria can trade genes on plasmids.
What is lateral gene transfer?
500
This is the definition for genetic drift.
What is a random change in allele frequency in a population?
500
This type of selection happens when the middle of the phenotype has a higher fitness than the extreme phenotypes. For example, male frogs call at a certain frequency to attract a mate. If the frequency is too high or too low, females can’t hear him. Therefore, most frogs have a very narrow range of frequencies at which they can call.
What is stabilizing selection?
500
This is the definition of genetic equilibrium.
What are unchanging allele frequencies in a population?
500
This type of isolation happens when species reproduce at different times, and can therefore not mate with each other.
What is temporal isolation?