A new daughter species (B) can originate suddenly when a new chromosome arrangement develops in the parent species (A). A fracture of a large chromosome occurrs in the germ cell line in individual A5. Next we see two fissions in descendant A8. When a new type of  chromosome develops from a fusion of the fragments in B1, the stage is set for a speciation event. These chromosomes are depicted as they appear in the gamete forming cells in the metaphase I stage of meiosis (see figure 4-2).