What are three reasons that organisms interact?

The organisms interact with each other first for reproduction purposes. They also interact for food which they may share or compete for. Lastly, they interact each other to defend themselves to form allies or enemies. All of these boil down to us interacting for survival. 

One reason may be mating for reproduction purposes- this occurs between individuals of the same speciesSecond is competition for resources and territory/nicheThirdly is looking for food through predation, parasitism or symbiosis Other reasons are the nurturing of the young

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