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August 1, 2009

Speciation in Action

The process of evolution is the way in which organisms change into something else. speciation, the process that splits two populations of the same species into two separate species, is central to evolution. Scientists can observe genetic changes in the lab, and can see the results of speciation in many different animals and plants. Darwin's Galapagos finches are still a wonderful example of this. However, there aren't many opportunities to catch the process of speciation in action. A little species of flycatchers has provided one of these rare opportunities.

J. Albert Uy, of Syracuse University, has conducted a study of the Monarch flycatchers, common on the Solomon islands. There are two varieties of this little bird, separated by a change in only one gene. Because of these, the flycatchers on one island are all black; the flycatchers on another have chestnut-colored bellies. The males of the species are very territorial; if another male enters an individual's territory, the intruder is attacked. Yet, interestingly, chestnut flycatchers rarely attack black flycatchers, and visa versa. This suggests that the chestnut and solid black varieties no longer recognize each other as potential competitors. This, in turn, means there is little to no interbreeding between the varieties. As a species is defined as a set of creatures that can mate and produce viable offspring, the two varieties of Monarch flycatcher are on a path to become separate species.

This is an amazing new piece of evidence to evolution. The fossil record is good, but too incomplete to provide absolutely definitive evidence. Microevolution (evolution on a very small scale, that doesn't necessarily create new species) can be readily observed in the lab, but macroevolution, like what is occuring now with the Monarch flycatchers, is not easy to see in action. Hopefully, these populations continue to be observed over time, so that the process of speciation and evolution can be documented.

Credit: Science Daily- Study Catches Two Bird Populations as They Split into Separate Species