Antarctic fish deploy antifreeze proteins to survive in cold water. Tasty viceroy butterflies escape predators by looking like toxic monarchs. Disease-causing bacteria become resistant to antibiotics. Everywhere you look in nature, you can see evidence of natural selection at work in the adaptation of species to their environment. Surprisingly though, natural selection may have little role to play in one of the key steps of evolution-the origin of new species. Instead it would appear that speciation is merely an accident of fate.
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