The Importance of Geographic Isolation

Although Darwin and Mayr both contributed enormously to the topic of speciation, they had two totally different views on the main mechanism driving it. Darwin noticed geographic isolation but discounted any importance in it believing natural selection to be the driving force, while Mayr believed that geographic isolation was the driving force of speciation and founded the theory of allopatric speciation. For decades Mayr's idea has been the traditional method thought to result in the highest amount of speciation, but recent support has shifted from allopatry and Darwins gradualism to rapid and sporadic periods of speciation with periods of relative equilibrium regardless of geographic barriers.

Darwin, the father of evolution was amazingly correct or close to the truth on most of his theories regardless of modern day proofs such as genetics. Darwin first noticed a pattern of speciation on the Galapagos islands when the vice-governor, Mr Lawson, told him that he could tell what island each of the tortoises were from simply by looking at them. Darwin found this unbelievable, until his own observations confirmed Mr. Lawson's claim (Schilthuizen 2001). Darwin believed that natural selection was the driving force behind speciation. "The passage from one stage of difference to another and higher stage may be, in some cases, due merely to the long-continued action of different physical conditions in two different regions; but I have not much faith in this view, and I attribute the passage of a variety, form a state in which it differs very slightly form its parent to one in which it differs more, to the action of natural selection." (Darwin 1859).

In order for natural selection to occur there needed to be large populati...

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