George Turner is a professor of evolutionary biology and biodiversity at the University of Hull in England. He agrees that animal evolution through hybridization may be much more widespread than previously believed.
As DNA analysis of different species becomes more sophisticated and extensive, he expects other examples to emerge.
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"I think this kind of speciation is most likely in animals were there are lots of similar, fast-evolving species, such as in certain types of insects and fish," he added.
Fish Hybrids
Turner says recent evidence indicates that some fish species also evolved as hybrids.
German researchers have studied cichlids (a type of tropical freshwater fish) living in tiny volcano-crater lakes in Cameroon, West Africa. Their studies have shown that at least one cichlid species started off as a hybrid.
Among cichlids this process likely takes thousands of years. The Lonicera fly's evolution, however, has occurred only in the 250 years since its honeysuckle host plant arrived in North America.
The introduction, via humans, of non-native species makes speciation through hybridization more likely, says Schwarz, the Penn State ecologist.
"On the one hand, introduced organisms provide new habitats," he said. "On the other, one could imagine that introducing a parasite that is closely related to a native species could lead to hybridization and, as a consequence, to the formation of new [species] that might be able to utilize a previously unused host."
"Evolution hasn't ended," George Turner added. "New species are evolving, and humans can have a big influence on that process."
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