Parasitic chromosome

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Parasitic chromosomes are “selfish” DNA pieces that copy themselves and are passed on during cell divisions, even if they don’t help the organism. They can stay in a population even if they slightly reduce survival because of their selfish behavior. These chromosomes are often B chromosomes, which aren’t present in every individual and aren’t required for basic life functions (unlike the essential A chromosomes). Parasitic chromosomes are a type of selfish genetic element. If they are too harmful, natural selection can remove them, but they can still spread if they act selfishly. An example is the b24 chromosome found in grasshoppers.