Dry, mountainous regions like the Maghreb, the Caucasus, most of Iran and Central Asia are also better adapted to herding than to agriculture, which may be why there is more haplogroup J than G in these regions. The same is true within Greece; Thessaly is better suited to agriculture and has a lot of hg G, while Crete is better suited to (goat) herding and has a lot of hg J2. In Iberia, hg G is more common in the wetter Northeast, while J1 and J2 are both more common in dryer Andalusia and Castilla-La Mancha.
I am not sure HG G is relevant Hg in Maghreb history. There are just few G samples there which I believe migrated in relatively recent times. Circassians were probably mostly responsible for G in Egypt and neighboring countries. 30% of Moroccan samples are Jewish.
I have never heard G is outnumbered by any group in Caucasus overall, at least not enough for a claim above mentioned.
Also, I would consider a fact that today's Adygea is just a mere fraction of an earlier population and this didn't happen naturally. A reliable data say the amount of people that were deported to Turkey was 1.500.000 in 1864, while Russian data shows only 500.000. Out of these 1.500.000 just over 480.000 survived. Their descendants are today living as 4.000.000 strong diaspora. It is not a surprise that the Russian authorities keep the history of Circassians under a thick cover of censorship.
Comparatively, today's Serbia has some 7 million people and in 1864 had less than 500.000. I am not mentioning how many lives war with Russia claimed. After the final solution of the Circassian question not more than 10 per cent of the original Circassian population remained in Russia in isolated islets in today’s Kabardino-Balkaria, Karachay-Cherkessia, Adygea regions and in a few villages in Sochi area.
Circassia-Adiygea had 12 tribes with Shapsug tribe as the biggest.
There is less G in Armenia, Azerbaijan, and generally among tribes and states in south and east of Caucasus. In J maps I presume a route along the sea as a one of the routes of J and I suspect some of it arrived in Caucasus along the Caspian sea, therefore maintaining today's disposition.
Iran data is relatively unknown for now, but still I would not use 101 comparison of HG G to any other group as a relevant deductive material here. It is one of rarest groups (outside mountains), and for that reason I would not compare it to other groups in numbers, but rather consider its relative occurrence, and preferably, would have taken this into account as a possible sign of different times of arrival in this area, where in terms of time and genes i suspect, a dispersion and lowering in numbers of an older gene. There is much of G* then G1*...g2a3b and there is quite a time gap between them.
Central Asia is by my opinion a place where G was never a relevant or standalone HG, but rather a relatively recent companion type HG, and as such not creditable of any significant human achievement there, let alone as progenitor of farming who found no adequate soil.
As for Thessaly, they appear to me as if they came down from mountains (or somewhere else) in recent times, and thus maintained this rounded form we can see on the G map, rather then being so distinctively circular in appearance for ages.
In Spain they are mostly in Cantabria 10.5%, and again in a mountainous region.
This does not necessarily mean I oppose the division of groups as stated, but still, I am not sure I would use all of quoted as an explanation, especially when comparing G in numbers. In general, I might oppose one gene one vocation, but I believe this was vocational spreading and carriers in general.