Species and Speciation

In This Chapter

^ Figuring out what a species is

^ Surveying the various mechanisms that can limit gene flow ^ Mastering the mechanisms of reproductive isolation

£ volution is nothing more than changes in gene frequencies in a group of organisms through time. Accumulate enough of these genetic changes in one population of a particular species, and that population could evolve into a new species. This process, whereby members of one species become another species, is called speciation, and it's one of the most fascinating areas of evolutionary biology.

As you can imagine, speciation can take a very long time — at least compared with the human life span. For that reason, scientists can't perform a single experiment in a laboratory that allows them to start with one species and watch a new one evolve. What they can do instead is observe the process in nature and study the individual parts of the process in the laboratory and in the natural environment.

Evolution doesn't need to lead to speciation. A species can evolve through time without splitting to create a second species. The study of speciation is the study of what factors are responsible for causing one species split into two species.

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