Mathematical models for life cycles of simple organisms

Even among simply structured organisms a fascinating variety of cellular communities from chain-forming bacteria to the formation and coordinated dissolution of large colonies can be found. Where does this diversity come from? And are there any fundamental rules for this diversity? General statements actually can be made applying mathematical models: Even without detailed knowledge about the biology of living organisms, one can understand which life cycles are theoretically feasible, and thus identify the conditions for the emergence of simple life cycles.