Have you bothered thinking about this at all? 

In and of itself? Economically? None. 

What counts is transportation costs (both time and money). An isolated island with good ports can have cheap transportation and so good economic integration with the rest of the world. 

A mountainous region in the center of a bustling continent is at a major disadvantage because of the cost and difficulty of moving goods in and out. 

Thus island countries such as Japan, England, and Taiwan have been very successful, while inland countries in Europe, places such as northern California, inland China, have not been economically successful. 

And consider the impacts of the Panama and Suez canals. They didn't affect geographical location, but they certainly affected transportation costs and hence economic integration and trade. 

On the other hand, politically, the situation is a little different. It is easier to move troops on land, so England, Japan, etc. have been able to use their island status to great military (defensive) advantage. 
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Geographic isolation is a term that refers to a population of animals, plants, or other organisms that are separated from exchanging genetic material with other organisms of the same species. Typically geographic isolation is the result of an accident or coincidence.