At What Level of Divergence Does Speciation Occur?

Before tackling the issue of the level at which speciation occurs as the result of divergence, we must first establish the definition of speciation. In the scientific community, this terminology is associated with the formation of new and distinctive species, from which a single evolutionary line splits into two or more genetically independent ones (Cook 1906). In essence, from one common ancestor derives two descendent species. Taking into consideration the controversial nature of what constitute a species, this is will refer to species as related individuals that resemble one another; they are able to breed with themselves, but not with members of another species (Rosenzweig 1995).

Now that we have established the meaning of speciation and species, we can proceed to answering the question of when speciation takes place. Speciation is more probable as a result of geographical isolation, which gives rise to reproductive isolation as a way to reinforce a divergent event that has already occurred. Since it has been established that the simplest form of speciation is lineage splitting, we must thus, understand how the split of one common ancestor can result in the formation of two separate and distinct species. Literature affirms that divergence of species is the outcome of accumulated differences between groups, which leads to the formation of new species (Salzburger et al. 2002). Usually this is a result of diffusion of the same species to different and isolated environments.

The isolation of environment plays the role of blocking the gene flow among the distinct population, allowing differentiated fixation of characteristics through natural selection to take place (Salzburger et al. 2002). Provided that most geographic...

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...ecies. Arguments and supporting examples were presented to illustrate how the formation of two or more species requires geographical isolation in order for reproductive isolation and natural selection to produce distinctive gene pools, thus resulting in the emergence of new species.

Bibliography

Cook, O.F. "Factors of species-formation." Science (1906): 506-507.

Hoskin, Conrad J, et al. "Reinforcement drives rapid allopatric speciation." Nature (2005): 437: 1353–1356.

Rosenzweig, M.L. Species Diversity in Space and Time. Cambridge: Cambridge University Press, 1995.

Salzburger, W, S Baric and C Sturnmbauer. "Speciation via introgressive hybridization in East African cichlids." Mol Ecol (2002): 619 - 625.

Sutera, R. 2001. The Origin of Whales and the Power of Independent Evidence. The Talk Origins Archive.