In which of the following interactions both partners are adversely affected ?

Options

A. Predation
B. Parasitism
C. Mutualism
D. Competition

Answer

To determine which interaction adversely affects both partners, let's analyze each option step by step:

### Step 1: Understand the types of interactions
We need to evaluate the four types of interactions provided in the options: Predation, Parasitism, Mutualism, and Competition.

### Step 2: Analyze Predation
- **Definition**: In predation, one organism (the predator) benefits by consuming another organism (the prey), which is harmed in the process.
- **Example**: A lion (predator) hunts and eats a deer (prey). The lion benefits, while the deer is harmed (it dies).
- **Conclusion**: In predation, only one partner is adversely affected (the prey). So, this option is incorrect.

### Step 3: Analyze Parasitism
- **Definition**: In parasitism, one organism (the parasite) benefits at the expense of another organism (the host), which is harmed.
- **Example**: A cuckoo lays its eggs in a crow's nest, benefiting the cuckoo while the crow suffers because it raises the cuckoo's young instead of its own.
- **Conclusion**: In parasitism, only the host is adversely affected. Thus, this option is also incorrect.

### Step 4: Analyze Mutualism
- **Definition**: In mutualism, both organisms benefit from the interaction.
- **Example**: Lichens, which are a symbiotic association between fungi and algae, where both partners gain advantages.
- **Conclusion**: In mutualism, both partners benefit, so this option is incorrect.

### Step 5: Analyze Competition
- **Definition**: In competition, two or more organisms vie for the same resources (like food, space, or light), which can lead to a decrease in resources available for both.
- **Example**: On the Galapagos Islands, the introduction of goats led to the extinction of the Abingdon tortoise because both competed for the same resources.
- **Conclusion**: In competition, both partners are adversely affected as they struggle for limited resources. Therefore, this option is correct.

### Final Answer
The interaction in which both partners are adversely affected is **D. Competition**.

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