Origin of Species
Origin of Species
Origin of Species
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Hybrid sterility isolates species. Thetwo species can mate and produce asterile but otherwise healthy <strong>of</strong>fspring.The sterility <strong>of</strong> the hybrid keeps thegene pools <strong>of</strong> the two species separate.When horses and donkeys are matedthey produce mules. Mules arecompletely sterile. The sterility resultsfrom problems in meiosis. Horseshave fewer chromosomes than donkeysand their genes are distributeddifferently among the chromosomes.In the mule, sterility is the result <strong>of</strong>inability to form viable eggs.Horses and donkeys are goodbiological species.11
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