2. Hummingbirds can have different beak lengths.

Question

They use their beaks to reach to the nectar (their food) at the bottom of flowers. Hummingbirds with longer beaks can get food from long flowers. Hummingbirds with shorter beaks cannot reach the nectar in long flowers. If a hummingbird can’t easily reach its food, it will die.

The diagrams below show three possible hummingbird populations.

Diagram titled Population 1 containing a row of 8 hummingbird icons labeled Short.
Diagram titled Population 2 containing 2 rows of 4 hummingbird icons each, one labeled Short and one labeled Long.
Diagram titled Population 3 containing a row of 8 hummingbird icons labeled Long.
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2. If their environment changes to have only long flowers, which of the following hummingbird populations will most likely survive?
Responses

a
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.

b
All the populations will survive because the hummingbirds will change the length of their beaks if they need to.
All the populations will survive because the hummingbirds will change the length of their beaks if they need to.

c
Populations 1 and 2 will survive.
Populations 1 and 2 will survive.

d
Populations 2 and 3 will survive.

Answer 1

The correct response is:

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

Explanation: In an environment with only long flowers, only hummingbirds with long beaks can reach the nectar. Population 1 has all short-beaked hummingbirds and would not survive. Population 3 has all long-beaked hummingbirds and would survive, but it lacks variation. Population 2 has both short and long beaked hummingbirds, which means that although some will be at a disadvantage (the short-beaked), the presence of long-beaked individuals ensures that the population has members capable of surviving in the new environment. Thus, variation is crucial for adaptation during environmental changes.