Endosymbiosis
that is my explanation hopefully its right
Natural variation provided the phenotypes that natural selection then acted on, over time causing evolution
Isolation can be due to behavioral, geographical, or temporal barriers. <span>Speciation can take place in two general ways. A single species may change over time into a new form that is different enough to be considered a new species. This process is known as anagenesis. More commonly, a species may become split into two groups that no longer share the same gene pool. This process is known as cladogenesis. There are several ways in which anagenesis and cladogenesis may take place. In all cases, reproductive isolation occurs. Hope this helps! </span>
Your answer is After DNA replication, the cell leaves S phase and enters G2, when the cell prepares for mitosis or meiosis. At the G2 checkpoint, the cell checks two things. First, it checks DNA for any damage that might have occurred during replication. It also ensures all the proteins needed for cell division are present.