How does asexual reproduction compare with sexual reproduction?

Answer 1

Asexual reproduction only involves mitosis, or binary fission. This leads to clones with identical genotypes.

This also results in low genetic variation within a species.

Sexual reproduction uses meiosis, indeed, sexual reproduction is the only function of meiosis.

In meiosis, the first step causing variation is called Crossing-Over, where portions of the paternal chromosomes and maternal chromosomes physically change places.

Next, the cell divides, each daughter cell taking half the chromosomes.

These haploid cells now have half the normal chromosome number (23 for humans), but the chromosomes are still in the commonly seen cross shape with two sister chromatids.

These now divide again, the chromosome number is still 23, but they are now in their single-strip form.

The result is four daughter cells with half the chromosomes of the original cell, and lots of variation.

Add to this the randomness if which human mates with which, and which sperm combines with which egg, and one can see how we've been able to keep up, evolutionarily, with bacteria.