The process of creating a new species is known as speciation. Speciation can occur when an event causes reproductive isolation of organisms within the species; this prevents the organisms from mating and producing hybrid offspring.
When: For reasons that are not completely clear, the data show the long-term dynamics of evolution to be quite slow." Across a broad range of species, the research found that for a major change to persist and for changes to accumulate, it took about one million years.