Stages of evolution of microorganisms.

The first living organisms arose about 3.5 billion years ago. They apparently ate foods of abiogenic origin and were heterotrophs. The high rate of reproduction has led: to the emergence of competition for food, and therefore, to divergence. The advantage was given to organisms capable of autotrophic nutrition – first to chemosynthesis, and then to photosynthesis. About 1 billion years ago, eukaryotes split into several branches, some of which gave rise to multicellular photosynthetic organisms (green, brown and red algae), as well as fungi.