Explain to what extent the process of meiosis contributes to this variability?

Moin,

well, what are the two (big) tasks of the meiosis?

Right! On the one hand, the halving of the chromosome set (which is irrelevant for the task) and on the other hand the mixing of the parent genetic material (which is very relevant for the task).

The mixing takes place once by recombination (i.e. the random distribution of the parent chromosomes to the germ cells), and then also by crossing-over events (during the prophase I of the first meiotic cell division). Both result in completely new combinations of the parental genetic material occurring in the formation of germ cells.

This ultimately leads to the variability of the genetic information increasing. The descendants of a couple of parents are never the same. They can show a certain family similarity, but they are neither phenotypically nor (and not quite) genotypically identical.

The increase in variability is such an immense advantage that, in nature, sexual reproduction as a whole has prevailed, even if this entails a huge effort.

Evolutive increases the survival of a species by variability because changing environmental conditions can be better absorbed by selective processes.

LG from the Waterkant