BIO 100

In a very small population of birds, assume 5 out of 20 alleles are the type that code for blue feathers. What is the allele frequency of the "blue feather allele" in this population?

0.25

According to the Hardy-Weinberg principle, if 75% of the alleles in the gene pool are A1 and 25% are A2, what is the proportion of individuals with genotype A1A2 in this population?

0.375

If two or more phenotypes in a population are both favored by selection, what is happening?

Balanced polymorphism

In a population, the most common phenotype represents the dominant allele. True or False?

False

From an evolutionary point of view, what important process occurs when a young male baboon leaves the troop that he was born in to join another troop?

Gene flow

If the tallest and shortest individuals of a population of humans do not survive and reproduce as well as the individuals of "average" height, which type of selection would most likely result?

Stabilizing selection

In one butterfly species, the colors of individuals range from white to black, with many shades of gray in between. If the butterflies in a mountain population become more and more similar in color over several generations (for example, if most butterflies are the same shade of gray), what kind of evolutionary force is likely acting on the population?

Stabilizing selection

Despite causing a life-threatening disease, the sickle-cell allele in some areas of Africa has remained in high frequency in those populations because it protects against malaria. In the United States, malaria was eradicated shortly before World War II by eliminating the mosquito that spreads the disease. What is likely to happen to the frequency of the sickle-cell allele in African Americans living in the United States?

The frequency of the sickle-cell allele will decrease.

Evolution can be defined as:

a change in the genetic makeup of a population over time.

Evolution by natural selection is:

a process that occurs as a result of differences in fitness.

A population is defined as:

all individuals of the same species located in a given geographic region.

In an equilibrium population:

allele frequencies do not change

Gene flow:

can spread certain alleles throughout a species.

Imagine that a species of bird with an intermediate beak size becomes two separate species with large and small beaks. This is an example of:

disruptive selection.

In a certain species of salmon, some adult males are extremely large whereas other adult males are very small, compared to the females. There are no intermediate-sized adult males in the population. This is probably the result of:

disruptive selection.

In the context of evolution, equilibrium means:

no change in allele frequency.

Habitat loss, natural catastrophes, and/or excessive harvesting of a species often result in:

population bottlenecks.

A population carries two alleles for a trait in which T is dominant and t is recessive. In the Hardy-Weinberg equation, 2pq represents the:

proportion of heterozygous individuals.

A population carries two alleles for a trait in which T is dominant and t is recessive. In the Hardy-Weinberg equation, p2 represents the:

proportion of homozygous dominant individuals.

A population carries two alleles for a trait in which T is dominant and t is recessive. In the Hardy-Weinberg equation, q2 represents the:

proportion of homozygous recessive individuals.

An allele frequency is the:

relative proportion of a given allele in a population.

Female finches, which do not sing, tend to choose to mate with males that sing a specific, elaborate song. This is an example of:

sexual selection.

Imagine that a mutation for red eye color becomes very common in a population of flies because female flies in this population prefer to mate with red-eyed males. This is an example of:

sexual selection.

Male fish that display a bright blue color attract more mates as well as more predators. Maintaining that blue gene in the population is an example of:

sexual selection.

Evolution by genetic drift is most obvious in:

small populations.

In general, each species of fruit fly in the Hawaiian archipelago is restricted to a single island. One hypothesis to explain this pattern is that new species formed after a small number of flies colonized each new island. This mechanism is called:

the founder effect

Imagine that one of the original four mice that escape from a research lab is blind due to a genetic defect. If the escaped mouse breeds and most of the mice born in subsequent generations are blind from birth, this is most likely a case of:

the founder effect.

Genetic drift results in a change in gene frequencies because:

the population size is so small that chance occurrences can alter gene frequencies.