I was drawn to this question as I have Sutherland in my background. What I have found through Ancestry.com was that your Sutherland's date back to at least the 12th Century. From what I have found, Alexander was married to a Ann Gunn and that his Father, John, was married to Mary Elizabeth Sinclair. John's father, William, was married to an Ann Gunn. Please contact me for more on this.
Bob Brodie