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The Importance of Geographic Isolation Essay

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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 …show more content…

For as all the inhabitants of each country are struggling together with nicely balanced forces, extremely slight modifications in the structure or habits of one inhabitant would often give it an advantage over others; and still further modifications of the same kind would often still further increase the advantage" (Darwin 1859). Darwin is describing sympatry in this paragraph and the competition and conquering of the parental generation by their "modified decedents" reducing its numbers and thereby its chance of further variation and improvement. The more branching of the groups the more destruction of the earlier less improved subgroups (Darwin 1859). Darwin believed that isolation was probably important but only to "check immigration of better adapted organisms" and could eventually "retard the production of species through natural selection, by decreasing the chance of the appearance of favourable variations" (Darwin 1859).

One of the first naturalists to expand on speciation theory was a German by the name of Moritz Wagner. In 1889 he proposed that during lengthy separations, changes would accumulate making different species, but noone acknowledged his theory for fifty one years until Ernst Mayr

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