The Role of ROS in Evolution
Evolution is understood as the process that leads to the variation of phenotypes observed along all species as first described by Charles Darwin in The Origin of Species (Darwin, 1859). We define evolution as a development process of lifeforms that is caused by mutation, reproduction and selection as a minimum set. Further important mechanisms as recombination and detailed properties of the gene transfer are neglected as we do not intend to present a reinterpretation of evolution but a small motivation how ROS might be a driving force in the origin of species.
As pointed out ROS plays an important role as an environmental constraint exhibiting selection pressure to organisms which have not developed the necessary systems for ROS scavenging. In the following chapters we will see that possibly the strongest environmental change that ever happened in the ecosphere was the big bang of ROS production after the development of oxygenic photosynthesis (5.1). In chapter 5.2 the role of selection pressure to drive evolution and its impact in conducting leaps in evolution is elucidated. We will shortly illustrate how genetic diversity is of major impact for the adaptivity of organisms to external contraints and changes of the environmental conditions than mutations, which are random products that do not lead to predictable directions of evolution. Selection pressure is a driving force for complexity in systems that follow simple rules. We will now close the circle from the very beginning of this book where the explanation for hierarchical structures was motivated by Steven Wolfram's cellular automata (see chapter 1).