Science is fascinating and sometimes unbelievable too like in this case.
If we think exploitation is a human trait born out of our greed, we are not alone, even fungi exhibit this behaviour! The fungus is a microorganism such as yeasts and moulds as well as the more familiar mushrooms.
Check out this Economist article quoting a study just published in Current Biology by Toby Kiers of the Free University of Amsterdam:
//In the soil, where plants’ roots meet fungal hyphae, there are trading posts. Like cunning merchants who know how to make a profit, fungi exploit resource scarcity by marking up their prices. They demand more nutrients from plants in return for their valuable mineral commodities.//