The rule of independent assortment by Mendel. Two things happen during meiosis that cause DNA variation78910:

Crossing over: During prophase I of meiosis, homologous chromosomes pair up and trade regions, which makes new gene combinations.

Selection on your own: At metaphase I, homologous chromosome pairs line up randomly on the equatorial plane. This makes different mixes of maternal and father chromosomes.

These steps make gametes, which are sex cells. Each gamete has its own set of genes. During ovulation, gametes join together, creating a child with a unique set of genes. Mendel's law of independent sorting is based on this idea. It says that the alleles of two or more genes are sorted into gametes without affecting each other. This means that the allele a gamete gets for one gene doesn't change the allele it gets for another. This rule describes how traits can be passed down without affecting each other, which helps to create genetic diversity.  (2023, January 9)

• Fowler, S., Roush, R. & Wise, J. (2023, January 9). Concepts of biology. Open Stax College.