The earliest cells on earth reproduced by division. This is termed asexual reproduction because the cell just divides into two identical cells. Widely dispersed populations can still reproduce. Cells are identical to parents and should survive well if conditions don't change.
Cells are identical to parents and so are vulnerable to the same environmental stresses.
The characteristics of the cells change very slowly there is very little innovation in survival strategies. Unchanging cells may be slow to take advantage of new energy sources. Asexual cell division is called Mitosis. Very, very, very simply, this is how it works. The cell is getting ready to divide.