Harbor seals live in northern oceans and have a layer of blubber (fat) that keeps them warm. Seals can have blubber of different thicknesses.

Question

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.

Diagram titled Population 1 containing a row of 6 seal icons labeled Thin Blubber.
Diagram titled Population 2 containing 2 rows of 4 seal icons each, one labeled Thin Blubber and one labeled Thick Blubber.
Diagram titled Population 3 containing a row of 6 seal icons labeled Thick Blubber.
audio
speed
6. If their environment changes to have warm water, which of the following seal populations will most likely survive?
Responses

a
Populations 1 and 2 will most likely survive.
Populations 1 and 2 will most likely survive.

b
Populations 2 and 3 will most likely survive.
Populations 2 and 3 will most likely survive.

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

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

Answer 1

The best response is:

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

Explanation: In warm waters, seals with thick blubber are at risk of overheating, so a population with variation, like Population 2, which contains both thin and thick blubber seals, would have individuals that could potentially survive in the warmer environment. Populations 1 and 3, which consist only of seals with thin or thick blubber, respectively, would likely face challenges in adapting to the change in temperature.