Final answer:
Meiosis is essential to sexual reproduction as it produces haploid cells necessary for fertilization, reduces chromosome numbers, and introduces genetic variation which is vital for species survival and adaptation.
Step-by-step explanation:
Meiosis is essential to sexual reproduction because it allows diploid organisms (those with two sets of chromosomes) to produce haploid cells (with a single set of chromosomes) that can fuse with another haploid cell during fertilization. This fusion results in a unique diploid offspring, different from both parents. The process of meiosis not only reduces the chromosome number by half but also introduces genetic variation through crossovers during prophase I and random assortment at metaphase I. This genetic variation is crucial for the survival and reproduction of a species, providing an adaptive advantage in changing environments. Sexual reproduction via meiosis and fertilization has been evolutionarily successful, and is why the vast majority of eukaryotic organisms reproduce in this way.
By mixing genetic material from two parents, meiosis generates diversity in the gene pool. This contrasts with asexual reproduction, where the only source of variation is mutation. Over time, a sexually reproducing population is more likely to survive and adapt to environmental pressures than its asexually reproducing counterparts. Therefore, meiosis is not just a mechanism for the formation of gametes but also a promoter of genetic diversity, which is a key component of evolution and species survival.