New species arise by the 
New species arise by the splitting of lineages. A small sub-population of the ancestral form gives rise to the new species. The new species originates in a very small part of the ancestral species' geographic range in an isolated area at the periphery of the range. New species develop quickly. So said Eldredge and Gould in a famous 1972 paper with a new explanation of the fossil record. For 10 points, what two-word name is given to this biological theory?
New species arise by the splitting of lineages. A small sub-population of the ancestral form gives rise to the new species.