The reason is because the mule is sterile and cannot breed other mules.
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Anti-satellite weapons, which are primarily surface-to-space and air-to-space missiles, have been developed by the United States, the USSR/Russia, India and the People's Republic of China. Multiple test firings have been done with recent Chinese and U.S test program that destroy an orbiting satellite.
Natural selection is what makes evolution occur, it is one major cause of evolution. Certain species survive and die due to natural selection. The strongest and most evolved will survive vs the weak and not evolved species. Species have to adapt to their environment and natural selection is constantly causing species to keep evolving over time.
Answer:hope this helps thanks for the luck