Final answer:
Meiosis I generates genetic diversity through crossing over during prophase I and independent assortment during metaphase I. Meiosis II separates recombined chromatids into unique gametes. Together, these processes produce gametes with a high degree of genetic variation.
Step-by-step explanation:
Meiosis I and II contribute to genetic variation in several ways. In meiosis I, genetic diversity is introduced through two mechanisms: crossing over and independent assortment. During prophase I, crossing over occurs between the nonsister chromatids of homologous chromosome pairs, resulting in recombinant chromatids with new combinations of maternal and paternal alleles. During metaphase I, independent assortment takes place as the homologous chromosomes are arranged randomly at the metaphase plate, which leads to various combinations of these chromosomes in the resulting gametes. In meiosis II, while similar to mitotic division in the segregation of sister chromatids, the chromatids that separate contain genetic information that has been recombined in meiosis I, thus contributing to further variation in the gametes.
While meiosis II does not introduce new recombination through crossing over, it is the process where the chromatids, now carrying recombined alleles from meiosis I, are distributed into separate cells, which eventually develop into unique haploid gametes. The combination of these two processes ensures that the gametes produced will have diverse genetic combinations, leading to the potential for a multitude of genetic outcomes during fertilization.