Answer:
- Independent assortment of chromosomes
- Crossing over
Explanation:
Independent assortment of chromosomes
We each have a diploid genome that is used to make haploid gametes. The selection of which combinations of chromosomes (and the particular alleles they hold) that are passed on to the gametes is random. I.e. 1 gamete could have the paternal chromosomes 1, 4, and 6, and maternal 2, 3 and 5. Another gamete could have paternal 2, 4, and 6, and maternal 3 2 and 5.
This produces unique combinations of alleles that are passed onto the next generation after sexual reproduction.
Crossing over
Crossing over occurs when homologous chromosomes pair up and align during meiosis. When this happens, they can exchange genetic material at homologous sites. This means that even <em>within </em>chromosomes, there are new combinations of alleles being created to pass on to the gametes before sexual reproduction. That is, each chromosome will have chunks of maternal and chunks of paternal DNA.
Both of these features increase genetic variation by two mechanisms, and this is occurring in two individuals, producing genetically diverse offspring.
