Speciation

Speciation - Speciation Any mechanism of evolution must...

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Speciation Any mechanism of evolution must account for three categories of observation: First, the observation that populations can change through time; second, the seeming ‘good fit’ between organisms and their environment; third, the incredible diversity of life forms that roam, and have roamed, the planet. The mechanisms that we have encountered so far (natural selection, sexual selection and drift) have addressed the first two observations. Here we will discuss the third: the origin of diversity. Natural selection is a theory of within-species change . In order to generate diversity we need a mechanism of splitting species and allowing the recently split species to remain independent . This is the process of speciation . Speciation increases diversity. Extinction is the death of all members of a species and decreases diversity. What is a species? One definition: A population that under natural conditions is reproductively isolated from other populations. This is the so-called ‘biological species concept’ (BSC), although it is
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This note was uploaded on 02/02/2012 for the course BIO 203 taught by Professor Davidhaskell during the Spring '09 term at Sewanee.

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Speciation - Speciation Any mechanism of evolution must...

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