Speciation
In sympatric speciation, species diverge while inhabiting the same place.  Often-cited examples of sympatric speciation are found in insects that become dependent on different host plants in the same area.Berlocher S.H. and J.L. Feder 2002. Sympatric speciation in phytophagous insects: moving beyond controversy? Annual Review of Entomology 47:773-815