One evolving species vs speciation.

Taz, this scenario has actually occurred. When the Londoners built their underground subway in the 1880's, some of the prevalent surface mosquitos - Culex pipiens - flew down into the tunnels and were trapped there. Exposed to a radically different environment, constant dim lighting, uniform temperature, no seasonal changes, etc., they evolved (by drift and adaptation) to a new species: Culex molestans. While C. pipiens feeds almost exclusively on bird blood, C. molestans evolved a preference for human blood (hence its name). Pipiens and molestans do not interbreed and thus became distinct species in less that a century (I don't know how many generations that is).The great theologian Joseph Smith taught that the interior of the earth is hollow and inhabited by a people that live on the inside surface of the earthly shell - and he must be correct since he was told this by an angle of god.. (Apparently, the inner surface people invented Velcro long before we did.) He also taught that there is a hole at the north pole through which we could enter that inner world. Now that the polar ice cap is disappearing, we should be able to enter that world and test if that inner population is reproductively isolated from us outer surface critters. Genetic analysis should determine if and when our two groups separated.