MacLellan, or variants thereof, is a surname of Scottish or Irish origin. Clan MacLellan likely descends from Thomas of Galloway( illegitimate son of Alan, Lord of Galloway ) where Mac-a-ghilledhiolan (pron. Mac-il-iolan.) means "The son of the Bastard." We believe this line ultimately descends from Fergus of Galloway and that Fergus descends from Owen Calvus, the last King of Strathclyde. Other instances of the surname are likely an Anglicization of the Gaelic Mac Giolla Fhaoláin which means "son of the servant of (Saint Fillan ) Faolán". The personal name, Faolán, is thought to be a diminutive of faol, meaning "wolf" or "little wolf".
The primary goal of the MacLellan DNA Project is to find the common surname progenitor for each Y-DNA cluster of men who carry a version of the MacLellan/Clelland/Gilliland surname variants. Y-DNA surname projects like this, allow us to build a phylogenetic tree of men's direct paternal lineage since the Y-chromosome is passed down from father to son completely intact without any DNA contributed from the mother. Each time there is a mutation on the Y-chromosome it will be passed down to every generation of males that follows. We can use these mutations to build a tree and see which MacLellans share a surname progenitor. We can even find DNA mutation branches within the various MacLellan trees. Y-DNA also allows us to see where other surnames branch from MacLellans in order to help build a more comprehensive picture of common origins.
A secondary goal is to find the Chieftain line of Clan MacLellan. One way to uncover the chieftain line is to test MacLellans that can trace their lineage to the chieftain line and compare their Y-DNA. We can also try to age the various MacLellan Y-DNA clusters by using Genetic Distance( the number of mutations ) to see if they line up with the origins of Clan MacLellan. We can also look for surnames that we believe may have common origins with Clan MacLellan such as McEwen, McCowan, McLagan, McLaren, Cannon, Donaldson, and see if they share common Y-DNA.
A third goal is to provide a place for people of any surname to compare their autosomal "mixed" DNA with those that have MacLellan ancestors. This can be done by taking the Family Finder test which will find 5 generations of relatives.
http://www.dgnhas.org.uk/transonline/SerIII-Vol59.pdf ( start at page 49 )
https://babel.hathitrust.org/cgi/pt?id=inu.30000118588429&view=1up&seq=7 MacLellans from MacLagan perspective. McLagans share similar coat of arms.
https://archive.org/stream/howstandrewcamet00edin/howstandrewcamet00edin_djvu.txt St. Fillan relics and history including Maclellans and MacLagans.
https://books.google.com/books?id=a_FBAAAAcAAJ&pg=PP691&lpg=PP691&dq=%22a+mortar+piece%22 Some McLarens also have the same Coat of Arms/crest/slogan as MacLellans.