Name the association in which one species produces poisonous substance or a change in environmental conditions that is harmful to another species.

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the name of an association where one species produces a poisonous substance or alters environmental conditions in a way that is harmful to another species.

2. **Identifying the Type of Interaction**: In ecology, there are various types of species interactions. The interaction described in the question involves one species benefiting or remaining unaffected while causing harm to another species.

3. **Defining the Association**: The specific type of interaction where one species produces harmful substances or changes the environment in a way that negatively impacts another species is known as **Amensalism**.

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