How does the sexual life cycle of the human species introduce genetic variations?

Crossing over in meiosis, random assortment of homologous chromosomes, and fertilization.

Explanation:

In sexual reproduction, sex cells (gametes) from two parents combine in the process of fertilization, leading to the formation of a new, genetically distinct individual. Some organisms, including the starfish and cacti in the example above, can actually reproduce in either a sexual or an asexual mode.

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if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.