Mutualistic relationships

Options

A. do not have costs.
B. evolve when the benefits of the interaction outweigh the costs.
C. are rare.
D. are limited to plants and animals.

Answer

**Step-by-Step Text Solution:**

1. **Understanding Mutualism**: Mutualism is a type of symbiotic relationship between two different species where both species benefit from the interaction. This relationship is characterized by mutual investment, where each species provides resources or services that the other needs.

2. **Examples of Mutualism**: A classic example of mutualism is the relationship between algae and fungi in lichen. In this relationship, the algae perform photosynthesis, producing food that benefits the fungi, while the fungi provide nutrients and water to the algae, which helps them thrive.

3. **Investment and Benefits**: In mutualistic relationships, the investment made by each species leads to benefits that outweigh the costs. For instance, the algae invest in the fungi by providing food, while the fungi invest in the algae by supplying essential nutrients and water.

4. **Conclusion**: The key characteristic of mutualistic relationships is that they evolve over time, and the benefits of the interaction typically outweigh the costs involved. This is why option 2, which states that mutualistic relationships evolve and the benefits outweigh the costs, is the correct answer.