What do you mean by (+) and (0) relationship ?

Explanation

### Step-by-Step Solution

1. **Understanding Population Interactions**: In ecology, different species interact with each other in various ways. These interactions can be classified based on the effects they have on the populations involved.

2. **Defining Positive Relationship (+)**: A positive relationship occurs when one species benefits from the interaction while the other species is unaffected. This is represented by a "+" sign. An example of this type of interaction is commensalism, where one organism benefits and the other is neither helped nor harmed.

3. **Defining Zero Relationship (0)**: A zero relationship indicates that one species interacts with another, but there is no effect on either species. This is represented by a "0" sign. In this case, both species coexist without impacting each other's survival or reproduction.

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