Species Formation: Study Questions Long-Held Speciation Theory, Says Our Understanding Of How New Species Originate Is ‘Extremely Incomplete’

By Philip Ross on September 3, 2013 11:51 AM EDT

new species
New species of animals still crop up every now and then. Pictured here is the olinguito, a new animal identified in August in South America. It’s the first carnivore species to be discovered in the American continents in 35 years. (Photo: Reuters)

Species formation is a mysterious thing, with ideas about the evolution and origin of new species having themselves evolved greatly over the centuries. The dominant theory today is that new species mainly come about when barriers to reproduction - either geographic or genetic - inhibit animal populations from breeding.  While fossil records clearly show a direct relationship between isolation and the origin of new species, exactly how speciation, the process of new species formation, works still puzzles evolutionary biologists.

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Researchers from the University of Michigan and the University of Chicago question the long-held notion that new species originate through isolation. They tested the theory that barriers to reproduction directly affect the rate of speciation, and found little evidence that the former promotes the latter.

The team of evolutionary biologists studied the speciation rates of bird and fruit flies. Phys.org reports that the researchers compared the speciation rates of these well-documented animals with genetic indicators of reproductive isolation. They then created computer models to conduct the comparison.

Their findings, published Monday in the online publication the Proceedings of the National Academy of Sciences, say there just isn't enough evidence there to say that these two things are related.

"The rate at which genetic reproductive barriers arise does not predict the rate at which new species form in nature," Daniel Rabosky, assistant professor in the U-M Department of Ecology and Evolutionary Biology said in a press release. "If these results are true more generally-which we would not yet claim but do suspect-it would imply that our understanding of species formation is extremely incomplete."

According to Rabosky, evolutionary scientists have been studying the "wrong things," erroneously grounding their theories in the assumption that species form mainly through geographic or genetic isolation.

"To be clear, reproductive barriers are still important on some level," Rabosky continued. "But our results question whether genetic reproductive barriers played a major role in how those species formed in the first place."

In August, Smithsonian researchers announced the discovery of a new species of mammal in the forests of Ecuador and Colombia. Huffington Post reports that the olinguito, which looks like a miniature raccoon with the face of a teddy bear, belongs to the same order as dogs, bears and cats.

Its identification marks the first discovery of a new species in the Americas in 35 years. From The Manitoban:

Evidence of the olinguito's status as a distinct species was given by Kris Helgen, curator of mammals at the Smithsonian National Museum of Natural History. This work took Helgen and his team of eight scientists 10 years to complete. The project was first conceived by Helgen in 2003 when he found a mislabelled collection of olinguito pelts and skulls in Chicago's Field Museum of Natural History...

...These specimens were believed to be odd-looking olingos, larger tree-living carnivores that are closely related to olinguitos. Helgen noticed that these odd specimens had smaller teeth, longer fur, and were smaller in size than olingos. The olinguito specimens were found at much higher elevations than those at which olingos usually reside.

"Most people believe there are no new species to discover, particularly of relatively large charismatic animals," Case Western Reserve University anatomy professor Darin Croft told The Huffington Post. "This study demonstrates that this is clearly not the case."

Read more from iScience Times:

Walking Shark: New Species Discovered In Indonesia 'Walks' On Ocean Floor, Causes Nightmares

Slow Loris Video: Are Cute Animal Viral Videos Harming Endangered Species? [VIDEO]

New Ant Species: U.S. Biologists Name 33 Kinds Of Central American And Caribbean Ants, Some After Ancient Mayan Lords And Demons

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