What does being in Hardy-Weinberg equilibrium mean for a population?

A population of squirrels that contains a wide variety of phenotypes has a:

To be in Hardy-Weinberg equilibrium, a population must be

In Australia, all finches are yellow. In England, all finches are green. A green finch flies into the cargo area of a plane in London. The plane flies to Australia and the bird exits the plane. The bird reproduces and now there are both yellow and green finches in Australia. What mechanism of evolution was described?

Two bighorn sheep fight over a female. The strongest male with the biggest horns will mate with the female. This is an example of what mechanism of evolution?

A population of orange, yellow, and blue butterflies lived in a valley. While the majority of the butterflies were in cocoons, a flood occurred destroying the majority of the cocoons. The few that survived were yellow or orange. No blue butterflies existed after the flood. This is an example of what mechanism of evolution?

In Madagascar, the flower known as Darwin's Orchid grows in many different colors. A human is hiking in Madagascar. He travels home to the United States. On the bottom of his shoes are seeds from Darwin's Orchid. These seeds fall off his shoes and grow in the United States. All Darwin Orchids in the United States are white. This is an example of what mechanism of evolution?

In Western Africa, a boy is born with a mutation in his red blood cells that cause them to be sickle-shaped. As a result, the malaria virus cannot bind to his red blood cells. The boy is resistant to the malaria virus and survives long enough to reproduce and pass on the sickle-shape of red blood cells to his offspring. This is an example of which mechanism of evolution?

When Christopher Columbus came to the Americas, he randomly chose 3 chickens from Spain to bring along. These 3 chickens were the only chickens to breed in the Americas for hundreds of years.

Organisms better adapted to their environment tend to survive and produce more offspring. Their genetic profile becomes more common in the population over time.

In 2013, Typhoon Haiyan is estimated to have killed over 500 water buffalo in the Philippines. Water buffalo are used in the Philippines to plow crops. Many of the water buffalo that perished were concentrated near farms. These animals are more muscular than buffalo allowed to roam free.

The Afrikaner population of Dutch settlers in South Africa is descended from a few colonists. Today, the Afrikaner population has an unusually high frequency of the gene for Huntington's disease.

The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestor that interbreed.

A catastrophe kills many individuals in a population, leaving a small number of individuals to interbreed. These individuals may have different genes than the original population.

More severe illnesses exist among certain Jewish groups. Ashkenazi Jews, for example, have a particularly high chance of suffering from Tay-Sachs disease, a fatal condition in young children.

According to Genetic drift (bottleneck or founder) tends to ___________ genetic variation (diversity).

Which of the following is an example of the bottleneck effect?

Hunting reduced the population size of the northern elephant seal to as few as 20 individuals at the end of the 19th century. Their population has since rebounded to over 30,000, but much have less genetic variation than a population of southern elephant seals that were not intensely hunted. How is the lack of genetic variation related to the hunting episodes of the 1800's?