The point of the three species in Tribus is that they are "rhizobacteria" and don't compete with each other. They are very active in the rhizosphere region of the soil in particular and the three different species help plants uptake different nutrients like Nitrogen, Phosphorus, and potassium. It's not all about diversity for microbes-- the rhizosphere region of the soil is a competitive environment where the strong survive and that's what Tribus is...a consortium of bacteria that can work together to mobilize both macro + micronutrients in the rhizosphere region. They are attracted to plant roots because the roots exude organic acids which are a food source for the bacteria in Tribus.