What is a ring species?		An offspring derived the the reproduction of closely related species e.g. mule
What are post zygotic isolating mechanism?		Zygote mortality, poor hybrid fitness, hybrid sterility
What is sympatric speciation?		Populations become geographically isolated which restricts gene flow and each are subjected to different selection pressures. They therefore become reproductively isolated over time and form new species
What is allopatric speciation?		A biological phenomena where a connected series of closely related populations, distributed around a geographical barrier, in which adjacent populations of the ring can interbreed but those at the extreme end are reproductively isolated from one another
What are hybrids?		When a new species is formed in the same area. This may occur through change in host preference. When genetic differences are built up and RIM's are achieved, a new species is formed