Question

1. using the 10% rule, explain why predators such as hawks, coyotes, and foxes are less abundant than insects or grasses in this ecosystem.

the higher you go up the pyramid, the less
amount of energy there is for all
the other animals to feed off of.

1. based on the scenario, describe one piece of evidence that supports the idea that prairie dogs could be a keystone species.

i dont know

1. describe the chain of cause-and-effect events (a trophic cascade) that starts with the loss of prairie dogs and ends with changes in predator populations such as hawks and coyotes.
2. if humans introduced a new predator, such as a large hawk or feral dog, into the grassland ecosystem, predict how this might affect prairie dog populations, plant growth, and other species in the food web. explain your reasoning using the concepts of trophic cascades and keystone species.

Explanation:

Question 2 (Subfield: Biology)

Step 1: Recall the 10% rule

The 10% rule states that only about 10% of the energy available at one trophic level is transferred to the next trophic level. The rest is lost as heat or used for metabolic processes.

Step 2: Identify trophic levels of the organisms

Grasses (producers) are at the first trophic level, insects (primary consumers) at the second, and predators like hawks, coyotes, foxes (secondary/tertiary consumers) at higher trophic levels.

Step 3: Apply the 10% rule to energy availability

As we move up trophic levels, the energy available decreases. For example, if grasses have 1000 kJ of energy, insects (eating grasses) get about 100 kJ (10% of 1000). Then predators eating insects would get about 10 kJ (10% of 100).

Step 4: Relate energy availability to population abundance

Lower energy availability at higher trophic levels supports fewer individuals. So predators, being at higher trophic levels with less energy available, are less abundant than insects (lower trophic level) or grasses (producer, lowest trophic level).

A keystone species has a disproportionately large effect on its ecosystem relative to its abundance. To support prairie dogs as a keystone species, we need evidence that their presence/absence significantly impacts the ecosystem (e.g., on other species, habitat, food web). For example, if prairie dogs’ burrowing affects soil structure, plant distribution, or provides habitat for other species (like burrowing owls), or if their grazing controls plant growth and affects herbivores/predators.

A trophic cascade is a series of cause - effect events across trophic levels. Start with prairie dog loss:

1. Prairie dog (herbivore, prey) population decreases.
2. Their prey (plants they graze on, e.g., grasses) may overgrow (since less grazing) → plant community changes (e.g., dominant grass species shifts).
3. Insects/herbivores that depend on those plants: if plant species change, their food source is altered → their populations may decline (if new plants are unsuitable) or increase (if new plants are favorable).
4. Predators of prairie dogs (hawks, coyotes) lose a key food source → their populations decline (due to less prey availability). Also, if insects/herbivores decline, their predators (other small predators) decline, which can further impact hawks/coyotes’ food web.

Answer:

According to the 10% rule, only ~10% of energy from one trophic level transfers to the next. Grasses (producers, 1st level) have more energy. Insects (2nd level) get 10% of grasses’ energy, and predators (3rd+/higher levels) get 10% of insects’ energy. Less energy at higher levels supports fewer individuals, so predators (hawks, coyotes, foxes) are less abundant than insects/grasses.

Question 3 (Subfield: Biology)