Reduction division (meiosis) is associated with sexual reproduction. The reasons for this are:
a. Since sexual reproduction involves the fusion of two types of gametes (male and female), they must have haploid number of chromosomes.
b. The cell (meiocyte) which gives rise to gametes often has diploid number of chromosomes and it is only by reducing the number by half that we can get haploid gametes.
c. Reduction division also ensures maintenance of constancy of chromosome number from generation to generation.