What is the effect of geographic isolation on speciation? Discuss with suitable examples?

Geographic isolation refers to population of organisms, plant and animals which are separated from members of same species thus cannot exchange genetic material. This separation may occur due to variety of reasons like barriers, natural events like earthquakes.
Effect of Geographic isolation on speciation:

• Long geographical isolation leads to reproductive isolation thus resulting in a new species.
• Species which are adapted to different conditions of environment, food availability develop for example Kaibab Squirrel and abert squirrel separated by Grand Canyon, distinguishing feature like forelimbs have gradually developed.
• Helps in biodiversity and development of unique species as found on islands of Madagascar, Australia.
• Development of unique species like Finches in Galapagos
• It leads to micro-evolution, development of species with little difference and does not lead to an altogether new species.
• Isolation results in reduction in gene pool for mating thus they miss out on genetic material which help them fight certain diseases like people of Finland lack certain genetic material from other races and ethnic groups.

Geographical Isolation provides an opportunity for creation of new species but does not create a new species. Creation of new species depends degree of reproductive isolation and prevention of interbreeding.