MODERN-day descendants of an ancient warrior sea-king whose sons started three major clans have been traced in a new DNA project.

Scientists have pinpointed genetic markers for a line descended from Dougall, King of the Isle of Man and founder of the ancient Scots kingdom of the Isles and Lorn.

Living from around 1140-1207, Dougall was the eldest son of Somerled, the ancient warrior sea-king and progenitor of the MacDonald, MacAllister, and MacDougall clans.

Now genealogy experts have discovered markers for the MacDougall clan.

Lead researcher Alasdair Macdonald, of Strathclyde University, said: "We all learned in high school biology that only boys have a Y-chromosome that creates maleness.

"The direct paternal ancestors of a man pass down their Y chromosome from generation to generation and the code locked within their DNA is unique.

"With today's advanced DNA testing techniques, we are able to detect many more mutations in the DNA sequences of MacDougall men who are alive today. 

"This has helped us identify ancient DNA mutations that are similar to but, importantly, different from those carried by men descended from Somerled's grandson, who was called Donald and was the progenitor of the MacDonald clan."

Somerled expelled his Scoto-Norse rivals from Argyll, Kintyre and the Isles but was himself a Norseman paternally, having a genetic signature more common in Scandinavia than in Scotland.  

That first genetic signature was discovered and published in 2005 by researchers at Oxford University and the US-based Clan Donald DNA Project has since enabled thousands of present-day MacDonalds around the world to trace their ancestry.  

Macdonald, lead researcher for the MacDougall DNA Research Project and Teaching Fellow in Genealogy at Strathclyde's Centre for Lifelong Learning, said the finding of the MacDougall DNA markers is "truly significant".  

The MacDougalls were once amongst the most powerful and influential families in Western Scotland.

However, their fate was to turn in the early 1300s when the fourth clan chief Alexander MacDougall allied the MacDougalls with "Toom Tabard" John Bailliol in his battle agianst Robert the Bruce for the Scottish Crown. 

Much of this story was told in recent Bruce movies such as Outlaw King and The Return of the King.  

Many lands and possessions were subsequently removed, before assets like Dunollie Castle near Oban were restored to the clan under the leadership of Ewan Gallda MacDougall several generations later.

A global dispersal then sent many MacDougalls out of Scotland over the next few centuries.

The DNA project is ongoing and men named MacDougall, or with names derived from MacDougall, can find more details and an application form for a free test at www.macdougalldna.org.