Tuesday, March 31, 2009

Understanding of Speciation

Speciation is the process of a single species becoming two or more species. Many biologists think Speciation is key to understanding evolution. According to biological species concept, species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. Speciation is thus seen in terms of the evolution of isolating mechanisms and is said to be complete when reproductive barriers are sufficient to prevent gene flow between the two new species. The problem is that the capacity to interbreed cannot always be tested neither the potential for interbreeding. For asexually reproducing organisms and fossils, this concept does not apply.

Modes of Speciation
Biologists recognize two types of speciation: allopatric and sympatric speciation. The two differ in geographical distribution of the populations in question.

Allopatric speciation: is thought to be the most common form of speciation. It occurs when a population is split into two (or more) geographically isolated subdivisions that organisms cannot bridge. Eventually, the two populations gene pools change independently until they cannot interbreed even if they were brought back together. In other words, they have speciated.

Sympatric speciation: occurs when two sub-populations become reproductively isolated without first becoming geographically isolated. Insects that live on a single host plant provide a model for sympatric speciation. If a group of insects switched host plants they would not breed with other members of their species still living on their former host plant. The two sub-populations could diverge and speciate.

Tags: Bio Technology, Bio Genetics , Genetic Variation

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