Stability and Populations

The graph shows that the honeybee population was stable and then decreased. Which statement describes births and deaths when the honeybee population was stable?

• There was the same amount of births and deaths.

• There were more births than deaths.

• There were fewer births than deaths.

• There were no deaths.

Which statement describes births and deaths when the population was decreasing?

• There was the same amount of births and deaths.

• There were more births than deaths.

• There were fewer births than deaths.

• There were no deaths.

What ideas do you have about what could cause the number of births to increase in a population?

• Increased number of deaths and birth rate remained the same.

• Increased number of births and deaths

• Decreased number of births and deaths

• Decreased number of deaths and increased number of deaths.

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The diagram above is called a food web. It shows the relationship between foxes and voles. What does the food web show?

• foxes eat voles

• voles eat foxes

• voles compete with foxes

• foxes compete with voles

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Foxes eat small animals called voles. In southern Sweden, scientists observed that when the vole population decreased, what will happen the fox population?

• Population will decrease

• Population will remain stable

• Population will increase

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Ecologists gather a lot of evidence from ecosystems. One useful piece of evidence is what each population eats. How do you think knowing “what eats what” helps ecologists to explain changes in population size?

• Ecologists need to know what populations eat because changes to the size of consumer or resource populations can change the size of other populations.

• Ecologists do not need to know what populations eat because changes to the size of populations can never change.

• Ecologists need to know what populations eat because changes to the weather can change the size of populations.

• Economist need to know what populations eat because changes to the food web can change the size of other populations.

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A population of Tule Elk lives in Bakersfield. Over 150 years, the size of the Tule Elk population decreased. What best explains the decreased in the size of the Tule Elk population?

• A lot of Tule Elk were born and none of them died.

• The Tule Elk population is always increasing because no animal eats Tule Elk.

• Fewer Tule Elk were born than died.

• More Tule Elk were born than died

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A population of Mountain Lions lives in southern California. Over 20 years, the size of the Mountain Lion population in the region increased. What best explains the increase in the size of the Mountain Lion population?

• The Mountain Lions population is always increasing because no animal eats Mountain Lions

• More Mountain Lions were born than died.

• Fewer Mountain Lions were born than died.

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Two organisms fighting for the same resources is known as:

• Predation

• Symbiosis

• Competition

• Dancing

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When a populations is known to be STABLE, it:

• there are more deaths

• stays mostly the same, over time

• there are more births

• horses live there

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