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Figure 7 | Biology Direct

Figure 7

From: From the scala naturae to the symbiogenetic and dynamic tree of life

Figure 7

Symbiogenesis, natural selection, and the dynamic Earth as key processes that caused biological evolution. The Last Universal Common Ancestor (LUCA) evolved into the earliest self-replicating proto-cells (ancient microbes) ca. 4000 to 3500 million years ago. Over the subsequent eons, these archaic microbes evolved into numerous bacterial ecotypes that today inhabit every micro-niche where organic molecules (or light) are available. Moreover, these micro-organisms gave rise to larger, eukaryotic cells via symbiogenesis (primary endosymbiosis). These nucleated cells further evolved into multicellular organisms, such as algae, fungi, animals and plants.

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