Hi Folks. Help me understand Darwin when he wrote that two or more varieties could be formed in a strictly continuous area. He also wrote he believed "many perfectly defined species have been formed on strictly continuous areas".
Isn't isolation neccesary for evolution? So if there are no geographical barriers to separate different groups of a species, can mere distance serve to isolate them?
Hypothetically, I'm thinking of a species of hare that has a range...let's say 300 miles wide. Wouldn't the genes of all the would-be varieties keep criss-crossing across the range, and keep the species pure? Or if the distance is great enough, can varieties form?
Thanks for any help.