Some other Sources of Genetic Variability
	In addition to mutation, other sources of the variation seen in sexually reproducing offspring include crossing over and genetic recombination during fertilization (union of egg and sperm). In crossing over which occurs in the production of sex cells or gametes in meiosis, there is an exchange of chromosome pieces between the chromosome pairs associated with each other in this process. Crossing Over and Genetic Variation Mutations, crossing over, and genetic recombination ensure that no two gametes formed as the result of sexual reproduction will be exactly the same. As a consequence, the offspring formed as a result of sexual reproduction will exhibit variations. Some of these variations will be better suited for survival than others, thus driving the process of biological evolution.
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