Speciation?

Question

Differentiate the allopatric, parapatric and sympatric.

Answer 1

1. Allopatric Speciation. This type of speciation is produced when a physical barrier separated a species into two separate areas and does not allow any further contact. Mountain building, glacial movement, river boundary movement, etc. are examples of geographical situations that can divide up a single species into two distance areas. When the species is split, microevolution will cause changes in the species to make them different in phenotype. Small populations have a much better chance to develop into a new species than larger populations. These small populations usually occur on the edges of a larger population. These fringe populations are good candidates for speciation. Their gene pool differs from the parent population, genetic drift will continue to cause chance changes in the gene pool of small populations until a larger population is formed. Different selection pressures are at work on there peripheral populations. Adaptive radiation is the evolution of many diversely adapted species from a common ancestor. Geographical isolation lends itself to this type of new species development.

2. Sympatric Speciation. This is a type of speciation that develops within the range of the parent population. This type of speciation does not include geographical isolation. It can occur rapidly if a genetic change results in a barrier between the mutants and the parent population.

3. Parapatric Speciation. In parapatric speciation, the new species evolve from contiguous populations. Parapatric speciation occurs as follows: Suppose that a population initially existed in an area to which it was well adapted, and that it then started to expand into a contiguous area in which the environment favored a different form. If the transition between the two environments was sudden, a stepped cline will evolve at the border.

As selection worked on the population in the new area, different genes would accumulate in it and the two populations would diverge to become adapted to their respective environments. If they diverged almost to be different species, the border would be recognized as a hybrid zone. The two populations would have separated while they were geographically contiguous, along an environmental gradient.

Answer 2

Hi. Allopatric: http://www.answers.com/main/ntquery?s=allopatric&gwp=13
parapatric: http://www.answers.com/parapatric?cat=technology&gwp=13
sympatric: http://www.answers.com/sympatric?cat=technology&gwp=13

Answer 3

don't know; look on line