When starting out in my Y-DNA quest to genetically map all the Kilcoyne's of Western Ireland, I expected to find the usual variants of the name Kilcoyne in the DNA lists of the testers. Coyne. Coen , etc. Of the 60 testers there are in the Kilcoyne/Coyne Project, I have found no such connection between the Kilcoyne and Coyne surnames. I am sure as time goes on, that this will change. This is where it stands now though.
One connection I see consistently across 4 unrelated Kilcoyne families, is the matching to the Coyle's. My initial thought was that it was a coincidence, that there must have been a non paternal event somewhere in these families. The two surnames are completely different clans. The Coyle's primarily being from Donegal and Tyrone. With Scottish and English lines as well. The Kilcoyne's exclusively being from Mayo and Sligo. So I set out to discover more. I encouraged the testers to upgrade their STR kits to the BigY700. I was lucky in having wonderful participation and several made that happen. The BigY is a far superior test than the standard STR tests. STR's (short tandem repeats) are not very reliable in determining genetic distance between testers. With the BigY, SNPs (single nucleotide polymorphism) are found in the y chromosome which enable the haplotree to build down genetic branches, which are much more helpful in seeing where families branched off more recent in time.
While waiting on test results and finding and encouraging others to test, I decided to take on the Coyle Y DNA project on FTDNA. The administrator for that Project was no longer interested in managing it, and was eager to hand it off to me. My thought was to combine the two Projects, but there are many Coyle's and variants of the name that have no connection to the Kilcoyne's. So, the best I could do was to encourage members of both groups to join both the Kilcoyne and Coyle Projects. Most of the testers in the Coyle Project are no longer active so I found it was easier to have my Kilcoyne's join the Coyle Project. I labeled each lineage in both the Projects according to color. So the Gold in the Kilcoyne group are the same as the Gold in the Coyle Project. See the results pages of both projects.
This is the name distribution of the kilcoyne and Coyle surnames on the 1901 census. https://barrygriffin.com/surname-maps/