Exam 16: How Populations Evolve

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 (e.g., if most butterflies are the same shade of gray), what kind of evolutionary force is likely acting on the population?

In central Africa, the frequency of the sickle- cell allele has remained stable over the years because the allele protects against malaria. In the United States, malaria was eradicated by eliminating the mosquito that spreads the disease. The decreasing frequency of the sickle- cell allele in African Americans since malaria was eliminated in the United States is an example of

Which of the following is most likely to experience genetic drift?

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

The elaborate courtship displays common among animals are the result of

When one species evolves a new phenotypic feature and another species evolves new adaptations in response, it is called

Explain how disruptive selection could lead to the development of two species from one original founding population.

In an equilibrium population

In the context of evolution, equilibrium means

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

Which of the following occurs due to chance events that change the allele frequencies in small populations?

A new predator is introduced to an area that can feed on any millipedes shorter than 200 millimeters. No millipedes that live in that area are longer than 15 millimeters. What will happen?

Multidrug- resistant bacteria

The extreme loss of genetic diversity that has occurred in cheetah populations due to overhunting is the result of

The type of selection most likely to act on a well- adapted population in a relatively constant environment is

Gene flow

Evolutionary adaptations are not always the "best" solution to a problem. Explain how the long necks of giraffes can be both advantageous and disadvantageous.

A population that maintains several different phenotypes of the same trait displays .

A city was intensively sprayed with the chemical DDT to control houseflies. The number of houseflies was immediately greatly reduced. Each year thereafter, the city was sprayed again, but the flies gradually increased in numbers until 10 years later when they were as abundant as they were before the control program began. Provide an evolutionary explanation of what happened.

Evolution by natural selection is