2. 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.
3. based on the scenario, describe one piece of evidence that supports the idea that prairie dogs could be a keystone species.
i dont know
4. 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.
5. 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.

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Accepted Answer

### Question 2 (Using the 10% rule, explain why predators such as hawks, coyotes, and foxes are less abundant than insects or grasses in this ecosystem)
# Explanation:
## Step1: 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.
## Step2: Identify trophic levels
Grasses (producers) are at the first trophic level, insects (primary consumers) are at the second, and predators like hawks, coyotes, and foxes (secondary or tertiary consumers) are at higher trophic levels.
## Step3: Relate energy transfer to abundance
Since energy transfer between trophic levels is inefficient (only ~10%), higher trophic levels have less available energy. Organisms need energy to survive and reproduce, so with less energy available, the number of individuals (abundance) that can be supported at higher trophic levels (like predators) is lower than at lower trophic levels (like grasses or insects).
# Answer:
Predators are less abundant because the 10% rule means only ~10% of energy from one trophic level (e.g., insects for hawks) transfers to the next. Lower trophic levels (grasses, insects) have more energy, supporting more individuals; higher levels (predators) have less energy, so fewer individuals can be sustained.

### Question 3 (Based on the scenario, describe one piece of evidence that supports the idea that prairie dogs could be a keystone species)
# Brief Explanations:
A keystone species has a disproportionately large impact on its ecosystem relative to its abundance. Evidence for prairie dogs as keystone species could be: (1) Their burrowing creates habitats for other species (e.g., burrows used by snakes, insects, or small mammals). (2) They are a key prey species, so their removal would cause predator populations to decline. (3) Their grazing affects plant community structure, influencing which plants thrive and thus impacting herbivores that depend on those plants. For example, if prairie dog burrows are used by multiple species for shelter, this shows their role in supporting biodiversity beyond their own survival.
# Answer:
One piece of evidence is that prairie dog burrows provide shelter/habitat for other species (e.g., snakes, insects, small mammals), showing their disproportionate impact on ecosystem biodiversity (a keystone species trait). Or: Prairie dogs are a primary food source for predators (e.g., hawks, coyotes); without them, predator populations would decline, demonstrating their keystone role in the food web.

### Question 4 (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)
# Explanation:
## Step1: Start with prairie dog loss
Loss of prairie dogs (a primary consumer/keystone species) occurs.
## Step2: Impact on prey/plant relationships (if prairie dogs graze) or direct prey for predators
If prairie dogs are a key prey for predators (hawks, coyotes) and also graze on plants:
- **Effect on plants (if they graze)**: With fewer prairie dogs, plant species they grazed on may overgrow (if they were a major grazer), changing the plant community.
- **Effect on predators' food source**: Prairie dogs are a food source for hawks and coyotes. With fewer prairie dogs, the predators' primary food source declines.
## Step3: Impact on predators
Since hawks and coyotes rely on prairie dogs for food, a decrease in prairie dogs means less food available for these predators.
## Step4: Impact on predator populations
With less food, the survival and reproduction of hawks and coyotes are reduced. This leads to a decline in the populations of hawks and coyotes. Additionally, if prairie dogs' grazing was important for plant diversity, the change in plant community (from step 2) could also affect other herbivores, which in turn could impact their predators, but the direct link from prairie dog loss to predator decline via food availability is a core part of the trophic cascade.
# Answer:
1. Loss of prairie dogs: Prairie dog populations decline or go extinct.
2. Impact on predators' food: Hawks, coyotes, etc., rely on prairie dogs as a key prey source. With fewer prairie dogs, the predators’ food supply decreases.
3. Impact on predator survival/reproduction: Less food means lower survival rates (due to starvation) and reduced reproduction (fewer offspring, lower offspring survival) for hawks/coyotes.
4. Resulting in predator population change: The populations of hawks and coyotes decline (decrease in numbers) as a result of reduced food availability from the loss of prairie dogs.
(Optional: If prairie dogs graze, their loss also causes plant overgrowth (e.g., grasses they grazed on), which could affect other herbivores, but the direct prey - predator link is the main trophic cascade here.)

### Question 5 (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:
## Step1: Impact on prairie dog populations
The new predator (large hawk/feral dog) will hunt prairie dogs. Since prairie dogs are a prey species, their population will decrease due to increased predation pressure.
## Step2: Impact on plants (trophic cascade - prairie dog as grazer)
Prairie dogs graze on plants. With fewer prairie dogs, the plants they grazed on will experience less herbivory. So, the abundance of these plants (e.g., grasses they feed on) will increase (overgrow) as there is less grazing pressure.
## Step3: Impact on other species (keystone species effect)
- **Prey - dependent predators**: Predators that rely on prairie dogs (original predators like coyotes, smaller hawks) will have less food available (since prairie dog numbers are down). This will lead to a decline in their populations due to reduced food supply.
- **Plant - dependent species**: The increase in plant growth (from reduced prairie dog grazing) will affect other herbivores. Herbivores that compete with prairie dogs for the same plants may increase in number (since more plants are available), while herbivores that rely on plants that were previously suppressed by prairie dog grazing may decline if those plants are now outcompeted. Also, species that use prairie dog burrows (e.g., snakes, insects) will be affected by the decline in prairie dog populations, as their habitat (burrows) becomes less available or changes.
## Step4: Synthesize with trophic cascade and keystone concepts
Prairie dogs are a keystone species, so their decline (from new predation) triggers a trophic cascade. A trophic cascade is a chain of effects through trophic levels: predator (new) → prey (prairie dog, -) → plant ( + ) → other herbivores ( ± ) and original predators ( - ). The new predator’s introduction disrupts the existing food web, showing how a keystone species’ population change (due to new predation) causes widespread ecosystem impacts (trophic cascade).
# Answer:
- **Prairie dog populations**: Decrease due to increased predation by the new predator (large hawk/feral dog).
- **Plant growth**: Increase (overgrow) because prairie dogs (a grazer) are less abundant, so less herbivory on the plants they eat.
- **Other species**:
  - Original predators (e.g., coyotes, smaller hawks) that rely on prairie dogs for food will decline (less prey).
  - Herbivores competing with prairie dogs for plants may increase (more plants available); species dependent on prairie dog burrows (e.g., snakes) decline with fewer prairie dogs.

**Reasoning (trophic cascade/keystone)**: Prairie dogs are a keystone species, so their decline (from new predation) triggers a trophic cascade. The new predator reduces prairie dog numbers → less grazing on plants (plants increase) → affects herbivores and original predators. This shows how a keystone species’ population change (due to new predation) causes widespread ecosystem impacts (trophic cascade) across trophic levels.

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Question

Explanation:

Question 2 (Using the 10% rule, explain why predators such as hawks, coyotes, and foxes are less abundant than insects or grasses in this ecosystem)

Step1: Recall the 10% rule

Step2: Identify trophic levels

Step3: Relate energy transfer to abundance

Step1: Start with prairie dog loss

Step2: Impact on prey/plant relationships (if prairie dogs graze) or direct prey for predators

Step3: Impact on predators

Step4: Impact on predator populations

Answer:

Question 3 (Based on the scenario, describe one piece of evidence that supports the idea that prairie dogs could be a keystone species)