Venturing beyond the Red Queen

Abstract

Abstract This chapter examines how networks of cooperating and competing species can reach a flexible stability, simultaneously remaining stable while retaining the ability to evolve in many directions. Cooperation among species alone cannot explain this, because such cooperation can only evolve if it makes the participating species, acting as a unit, better overall competitors in the larger ecosystem. We explore how these continually shifting cooperative and competitive interactions can result in a flexible, rather than an ossified, stable state. Remarkable new adaptations are free to appear, along with avenues for other members of the ecosystems to adapt to them. Such ecosystem flexibility explains the history of the evolution of oxygenic photosynthesis. This system, on which almost all of Earth’s life now depends, began its evolution as types of more-limited anoxygenic photosynthesis in two bacterial lineages. Gene transfers brought these photosynthetic mechanisms together in a third bacterial lineage. There, they evolved cooperative interactions that allowed them to use carbon dioxide and water to generate chemical energy and release gaseous oxygen as a “waste” product. This did not result in the immediate death of all anaerobic organisms that were sensitive to oxygen, however. We explore why, in spite of the overwhelming advantage of oxygenic photosynthesis, it took two billion years for oxygenic photosynthetic organisms to fully take over the planet. This was because ecosystems still had many routes by which their species could adapt to this new selective factor, slowing its advance and increasing life’s complexity and flexibility at the same time.