compare and contrast geographic and reproductive isolation?

Answer 1

Reproductive isolation can occur either by preventing fertilization, or by the creation of a degenerate or sterile hybrid, such as the case with the common mule and the hinny.

Geographic isolation, or allopatry, is a term used in the study of evolution. When part of a population of a species becomes geographically isolated from the remainder, it may over time evolve characteristics different from the parent population (due to natural selection). This is particularly likely to happen if the isolated population is small, because of founder effects, or if the population become isolated in an environment which makes new demands upon it.

If there is sufficient genetic change following geographical isolation, then if the geographical barriers are removed (perhaps due to human activity), members of the two populations will be unable to successfully mate with each other. At this point, a new species has emerged. Geographical isolation is thus a key factor in speciation, the formation of new species - also termed allopatric speciation.