Question

c. darwins 4 points:

• populations have variations:
• more offspring are produced than survive:
• those that survive have favorable traits:
• a population will change over time:

scenario 4: rabbits and drought
some rabbits eat only grass, while others eat berries and flowers. a drought limits flower and berry growth. rabbits have babies year - round, but many are eaten by predators or starve due to limited food.

a. what trait is selected against? for?

b. what is the selective pressure?

c. darwins 4 points:

• populations have variations:
• more offspring are produced than survive:
• those that survive have favorable traits:
• a population will change over time:

Explanation:

Part a

• Against: The trait of eating berries and flowers is selected against because the drought limits the growth of these food sources, so rabbits with this trait will struggle to find food.
• For: The trait of eating grass is selected for because grass is less affected by the drought (or at least the problem doesn't state grass is limited), so rabbits that eat grass will have a more reliable food source.

Selective pressure is the factor that influences survival and reproduction. Here, the drought (which limits flower and berry growth) and predation/starvation due to limited food act as selective pressures, but the main environmental pressure from the scenario's drought affecting food (berries/flowers) drives selection.

• Populations have variations: In the rabbit population, there is variation in diet—some eat only grass, others eat berries and flowers.
• More offspring are produced than survive: Rabbits have babies year - round, but many are eaten by predators or starve due to limited food, meaning not all offspring survive.
• Those that survive have favorable traits: Rabbits that eat grass (favorable trait as grass is more available) are more likely to survive, while those that eat berries/flowers (unfavorable trait with limited food) are less likely.
• A population will change over time: Over time, the proportion of rabbits with the trait of eating grass will increase in the population, as they are more likely to survive and reproduce, leading to a change in the population's dietary - trait composition.

Answer:

Selected AGAINST: Eating berries and flowers
Selected FOR: Eating grass

Part b