Final answer:
The agreement between the zoo and the farmers exemplifies mutualism, a type of symbiotic relationship where both species benefit. The zoo gets rid of waste, and the farmers get natural fertilizer.
Step-by-step explanation:
The zoo's agreement with local farmers to sell excess animal waste, which the farmers use as fertilizer for their crops, best exemplifies the ecological concept of mutualism. Mutualism is a symbiotic relationship where both of the coexisting species benefit from the interaction. In this case, the zoo benefits by disposing of its waste in a useful and environmentally friendly way, while the farmers benefit by receiving a natural fertilizer that can enhance their soil quality and crop production.
There are many examples of mutualism in nature, such as the relationship between nitrogen-fixing bacteria and plants, where the bacteria fix atmospheric nitrogen into a form that plants can use, while receiving carbohydrates from the plants. This kind of interaction is crucial for sustainable agriculture. Following this concept, mutualism is seen as the foundation for interactions that allow different species to thrive together by providing reciprocal benefits, much like the zoo and farmers in this question.