R-L21 in the Alsace/Rhineland

[barbarian_warlord]

I have encountered evidence of an elevated concentration of the haplogroup R-L21 in the Alsace/Rhineland regions of France and Germany which I assume would form a distinct cluster crossing the borders of both countries.
(search "The phylogenealogy of R-L21: four and a half millennia of expansion and redistribution")
This paper claims that it is close to 40% in the Alsace region and 35% in the Rhineland.
So if these figures are accurate then why would there be such a significant dominance of what is traditionally an Insular Celtic haplogroup on an area of Continental Europe?

[Dorquest]

My Haplogroup is R1B L21 - DF13 - ZZ10_1 - FGC42672 - MC14 My last name traces to Muehleberg Switzerland 1530. We think it might be a back Migration from the British Isles about 4 thousand years ago.

[MOESAN]

the mentioned study involves too little samples concerning Elsass and German South Rhinelands; this 40% of L21 are very too high compared to reality. Maciamo, who compiles a lot of surveys, founds only something like 5% to 10% for N-Elsass SW Germany, even less for S-Elsass and Switzerland.
A back migration into Switzerland? I think L21 was born around SW Britain (Cornwall?) or NW France or both (it's to say: in a pop linked with both sides of the Channel).

[Dorquest]

the mentioned study involves too little samples concerning Elsass and German South Rhinelands; this 40% of L21 are very too high compared to reality. Maciamo, who compiles a lot of surveys, founds only something like 5% to 10% for N-Elsass SW Germany, even less for S-Elsass and Switzerland.
A back migration into Switzerland? I think L21 was born around SW Britain (Cornwall?) or NW France or both (it's to say: in a pop linked with both sides of the Channel).

I might not have worded that correctly. What I meant was my direct paternal line does appear to have migrated to the British Isles - DF13 - ZZ10_1 - FGC42672 - MC14 - then at some point migrated back to continental Europe in ancient times, ending up in Switzerland. Which so far appears quite rare. Currently have almost 27 private mutations on Big Y Family tree. Not that R1B L21 was born in Switzerland.

[MOESAN]

I might not have worded that correctly. What I meant was my direct paternal line does appear to have migrated to the British Isles - DF13 - ZZ10_1 - FGC42672 - MC14 - then at some point migrated back to continental Europe in ancient times, ending up in Switzerland. Which so far appears quite rare. Currently have almost 27 private mutations on Big Y Family tree. Not that R1B L21 was born in Switzerland.

Then like this it's better worded, OK. But dating this NW towards SE move is a hard work, I think. Do you know if yout direct paternal line is well shared in Switzerland among R1b's, or rather a rare one there?

[Dorquest]

On Big Y, my Family is the only one. The family name has been in the US since the 1850's. Name exist in Switzerland, which we have traced back to 1530, have thought about reaching out to the distant relatives with the same last name to get them to test. After MC14.... all private mutations.