AP BIOLOGY

Detailed explanation-1: -Drawing on data from more than 50, 000 species (though this included few bacteria), the researchers found that speciation generally requires the accumulation of mutations over 2 million years. This held true across vertebrates, arthropods (a group that includes insects, arachnids and crustaceans) and plants.

Detailed explanation-2: -Speciation is the process by which new species form. It occurs when groups in a species become reproductively isolated and diverge. In allopatric speciation, groups from an ancestral population evolve into separate species due to a period of geographical separation.

Detailed explanation-3: -Speciation involves the genetic change in a subgroup of a population that renders the new population incapable of reproducing offspring with the original population. If a reproductive barrier occurs because of isolation by a physical barrier, the isolated population can evolve and develop into a new species.

Detailed explanation-4: -So, the correct answer is ‘Speciation only occurs slowly as small genetic changes accumulate from generation to generation’