A series of lectures on DNA and family history research from Who Do You Think You Are 2014 have been posted on YouTube. One of them is a talk by Alaisdair Macdonald, volunteer administrator for the Scottish DNA and R-L165 Projects at Family Tree DNA, entitled, Scottish DNA. Clans, Families and Surnames.
The sound quality of the lecture is not very good (microphone problems and too much background noise), so you will need to listen carefully. You will not see speaker, but you will see the PowerPoint presentation. The slides are informative and will sometimes help you out when you can't hear him properly.
He begins his talk with a brief introduction to DNA testing focusing on the Y-chromosome as it relates to surnames, which is the focus of this talk. His next topic was DNA testing on the families associated with the Lordship of the Isles. This was intriguing, but I was disappointed that he was spending so much time on the Highlands. But after the discussion of the McDonalds and other Western Highland families, he turned to the Hamiltons of the Lowlands. Then he realized he was almost out of time and breezed through the rest of his slides, most of which were unusual surnames found in the Lowlands. Clearly, he planned a balanced lecture, but did not time it right. He did make time to discuss Scottish surnames with unusual origins like the Arabian Peninsula, the Mediterranean, and Mongolia and a few DNA project that are ongoing in Scotland.
While, the unintentional focus on surnames of the Western Isles is unfortunate for those whose ancestors come from elsewhere in Scotland, it is fortunate for those of you with ancestors who emigrated from this region to the American colonies in the 18th century. The surnames Macdonald discusses are those connected to clan chiefs. Across the Highlands most chiefs leased large sections of their estates to tacksmen, or leaseholders. These men were usually blood relations who paid for their land with military service to the chief. They made their money by renting their land to tenant farmers. When chiefs began looking for way to increase their incomes an obvious solution was to get rid of the tacksmen and collect rents directly from the tenants. Many tacksman reacted by taking themselves and their tenants off to America. What this means in genetic and genealogical terms is at least a handful of these emigrants would be related to the chiefly families, many of whom are mentioned in Macdonald's talk. Now whether the tacksmen stayed in America and left descendants is another matter entirely.
n.b. I am an affiliate of Scotland's DNA, but I would have posted this anyway.