Amplify Natural Selection Test

Harbor seals live in northern oceans and have a layer of blubber (fat) that keeps them warm. Seals can have blubber of different thicknesses. Seals with thicker blubber are more likely to stay warm and survive in cold ocean waters. But, in warm ocean waters, thicker blubber can make the seals overheat and die. The diagram below shows a population of seals that live in an area of ocean. At time 1, the population had the same number of seals with thin and thick blubber. At time 2, after many generations, there were many more seals with thick blubber and fewer seals with thin blubber in the population. How did the environment change between time 1 and time 2? How did the population change?

• You cannot tell how the environment changed. With each generation, more seals passed on the gene for thick blubber to their offspring.

• The water became colder. Seals with thick blubber are more likely to survive, so the seals with thin blubber changed to have thick blubber.

• The water became colder. Seals with thick blubber are more likely to survive, so both kinds of seals passed on the gene for thick blubber to their offspring.

• The water became colder. With each generation, more seals with thick blubber survived long enough to pass on the gene for thick blubber to their offspring.

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Guppies are small fish that live in South American rivers. They can have different-sized spots on their bodies. The river bottoms are covered in rocks. Guppies with spots that are the same size as the rocks on the bottom are harder for bigger fish to see and catch. The diagram above shows a population of guppies that lived in a river. Scientists had previously only seen guppies with medium or large spots in this river; they had never seen any guppies with any other spot sizes. The diagram below shows how the population changed after many generations. Karina says the change in the guppy population was caused by a mutation. Miles says the change was caused by a change in the environment. Zora thinks both Karina and Miles are correct. Who do you think is right? Explain what happened to the guppies over many generations.

• Miles is correct: Karina's is not accurate which makes Zora's answers inaccurate also. Guppies with small spots become less common because they become less common because they couldn't survive very long and don't have a lot of offspring.

• Zora is correct: Both Karina's and Miles’s answers are accurate. Miles is correct because the environment must have changed to have small rocks. Guppies with medium or large spots became less common because they could not survive very long and could not have a lot of offspring. Karina is also correct because, at some point, a guppy must have been born with a mutation for the small-spot trait since there were no guppies with small spots before. The guppy with small spots survived in the environment with small rocks long enough to reproduce. Some of its offspring were also born with small spots. Over many generations, a greater number of guppies with small spots had offspring, so that trait became most common.

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How did the color of the trees in the squirrels’ environment change? Explain what happened to the squirrels over many generations.

• The squirrel's environment will did not change, the trees stayed the same color. New Squirrels were born, with the black fur on squirrels reproducing's more rapidly.

• The squirrels’ environment changed to have lots of black trees. At some point, a brown or a gray squirrel had a baby with a mutation for the black-fur trait. It was easier for that baby to survive, so it lived a long time and reproduced. It passed down its mutant black-fur trait to some of its offspring. Over many generations, these black squirrels had more offspring with black fur, so black fur became the most common trait. Most brown and gray squirrels died before they could have offspring, so, over time, fewer brown and gray squirrels were born, and those traits became less common.

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Harbor seals live in northern oceans and have a layer of blubber (fat) that keeps them warm. Seals can have blubber of different thicknesses. Seals with thicker blubber are more likely to stay warm and survive in cold ocean waters. But, in warm ocean waters, thicker blubber can make the seals overheat and die. The diagrams below show three possible seal populations. If their environment changes to have warm water, which of the following seal populations will most likely survive?

• Populations 1 and 2 will most likely survive.

• Populations 2 and 3 will most likely survive.

• Only Population 2 will survive because it is the only population with variation.

• All the populations will survive because the seals will change the thickness of their blubber if they need to.

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Eider ducks live in the ocean and have a layer of warm feathers underneath their regular feathers. They can have thin feathers, medium feathers, or thick feathers. These feathers help the ducks stay warm in cold water. Ducks with thicker feathers are more likely to stay warm and survive in cold water. But, in warm water, thicker feathers can make the ducks overheat and die. The population of ducks shown above lives in an environment that has always had very cold water. Could there ever have been ducks with thin feathers in this population?

• No ducks could have been born with the thin-feather trait because none of the adult ducks had that trait to pass down.

• No ducks could have been born with the thin-feather trait in the past, but some with that trait could be born in the future if the environment changes to be warmer.

• A duck could have been born with a mutation in its genes for the thin-feather trait and lived for a little while, but it would have been more likely to die before it had offspring.

• A duck could have been born with a mutation in its genes for the thin-feather trait, but having a mutation in its genes would have caused it to die when it was born.

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Scientists measured the beak length of a population of birds in a lake in 1960. They measured the beak length of the bird population again in 2010. What do the graphs show you about the variation in the beak lengths of the birds by the lake?

• There was the same amount of variation in 1960 and in 2010.

• These bar graphs do not show the amount of variation in the population.

• There was more variation in 2010.

• There was more variation in 1960.

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How would you describe the variation in this histogram?

• There is high variation

• There is no variation

• There is low variation

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Which of the following is an adaptive trait?

• yellow ostrilopes in a green environment with predators present

• yellow ostrilopes in a yellow environment with predators present

• multiple colors of ostrilopes in a yellow environment with predators present

• all of the ostrilopes dying off

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If this population is adaptive, after 50 years how will this population change if there is little to no rainfall?

• the thornpalms will stay about the same

• the thornpalms will shift to store less water

• the thornpalms will shift to store more water

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What would be something that would cause a population to be adaptive?

• a change in the climate/ weather

• predators

• low food supply

• high food supply

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