Define the term "speciation." Describe the conditions under which speciation usually begins. Describe the conditions under which speciation is considered complete.
Speciation, or the origination of new species, begins most often when two populations of the same species become allopatric, the state in which geographic separation of the two populations eliminates effective gene flow between them. Geographic separation can be caused by any physical or ecological feature that prevents a population's movement across it. Speciation is considered complete when the two original populations have evolved enough to have become sympatric, the state in which the two populations have developed over time completely separate gene pools so that the exchange of genetic material would be impossible even if the two populations came into contact again.
