A single-gene trait that has two alleles and that shows a simple dominant-recessive pattern will result in ____.
What is two phenotypes
100
When individuals with an average form of a trait have the highest fitness, the result is ___.
What is stabilizing selection
100
Genetic drift tends to occur in populations that are ___.
What is small
100
The genetic equilibrium of a population CANNOT be disturbed by ____.
What is a large population size
200
What are the two main sources of genetic variation
gene shuffling and mutations
200
The phenotypes for a typic polygenic trait can often be expressed as ___.
What is a bell-shaped curve
200
When individuals at only one end of a bell curve of phenotype frequencies have high fitness, the result is ___.
What is directional selection
200
The type of genetic drift that follows the colonization of a new habitat by a small group of individuals is ___.
What is the founder effect
200
The situation in which allele frequencies of a population remain constant is ___.
What is genetic equilibrium
300
In many kinds of organisms, inheritable differences are due mostly to ____________.
What is gene shuffling during gamete formation
300
A widow's peak in humans is an example of a _____.
What is a single-gene trait
300
Natural selection acts directly on ___.
What are phenotypes
300
In genetic drift, allele frequencies change because of ___.
What is chance
300
One of the conditions required to maintain genetic equilibrium
What is 1) random mating, 2) large population, 3) no movement into or out of the population, 4) no mutations, 5) no natural selection
400
Gene shuffling includes the independent movement of chromosomes during meiosis as well as _______.
What is crossing-over
400
Compared to a polygenic trait, a single-gene trait tends to have ____.
What is fewer phenotypes
400
NOT a way in which natural selection affects the distribution of phenotypes
What are chance events
400
Biologists consider the event of ___ a random change.
What is genetic drift
400
The factor that would most likely disrupt genetic equilibrium in a large population
What is mating that is not random
500
In a particular population, sexual reproduction can produce _____.
What is many different phenotypes
500
A _____ trait can have many possible genotypes, producing many possible phenotypes.
What is polygenic
500
In a population of finches in which one group of birds has a short, parrotlike beak and another group has a long, narrow beak, ____ has probably occurred.
What is disruptive selection
500
One similarity between natural selection and gentic drift is that both events involve a change in a population's ___.
What are allele frequencies
500
According to the Hardy-Weinberg principle, genetic equilibrium would be more likely in a population of mice if no ____ takes place.