Two species of ravens may merge into one: study

A new study suggested that two distinct species of ravens may hybridise and eventually merge into one, contrary to the well-known speciation where one species splits into two.

The study, published in the journal Nature Communications, has provided some of the strongest evidence of the phenomenon called speciation reversal, in two lineages of Common Ravens.

It is based on genomic data from hundreds of ravens collected across North America, reports Xinhua.

Common Ravens were considered a single species worldwide in 1999 when Kevin Omland, from University of Maryland, Baltimore County and the paper's co-author, started the project.

Omland reported the existence of two Common Raven lineages in 2000, one concentrated in the southwestern United States dubbed "California," and another found everywhere else (including Maine and Alaska in the United States, as well as Norway and Russia) called "Holarctic."

However, two undergraduates in Omland's lab, Jin Kim and Hayley Richardson, analysed mitochondrial DNA from throughout the western US and found the two lineages are extensively intermixed.

Researchers suggested that the two lineages diverged for between one and two million years, but now have come back together and have been hybridising for at least tens of thousands of years.

"The extensive genetic data reveals one of the best supported examples of speciation reversal of deeply diverged lineages to date," said Arild Johnsen, from University of Oslo.

Omland noted that humans are also a product of speciation reversal, with present-day human genome including chunks of genetic material from Neanderthals, Denisovans, and even perhaps a fourth group of early humans.

"Because speciation reversal is a big part of our own history," Omland said, adding, "Getting a better understanding of how that happens should give us a better sense of who we are and where we came from."

--IANS

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