We undrstand that there are specific lineages, but for the broader picture, it's better to look at ALL relevant evidence, don't get too bogged down on allegedly 'distant TMRCAs'. It also doesn't help the case if you are using Reich's/Laz's autosome-based definitions (which are sometimes dubious) for uniparental discussion (you've posted the above image hundreds of times all over the internet :))
These are some facts
- Zolotarevka site develops at the inception phase of Majkop, but at the far northern border of its oikumene . Zo1002 has excess Sho-Shu ancestry c.f. preceding CLV..
- J2b-L283 is missing in Sredni Stog, Khvalynsk, Cernavoda.
- Yamnaya lacks ZO ancesty, but can be modelled as Don/Ukr-N rich (female -mediated) LVC.
'Core Yamnaya' is actually a Z2103 mediate mass-expansion.
- beyond the Manych, L283 and a Z42941 both appear within a few Km of each other (Crihana Veche, Burusceni, etc). This means there was specific, targetted migration, and eventual assimiliation of a small minority in Molodova / SW Ukraine/ Nth balkans into a broader 'steppe front'
- So, as with the case of I2a-L703 or R1b-V1636, L283 is a para- or pre-Yamnaya lineage. However, unlike the case of I2a or V1636, which are present throughout the steppe before 4000 BC, L283 is absent and appears to trace an exclave of Makop metalsmiths. Calling it part of 'core Yamnaya' is fantasy, given its obvious absence in the expanding Yamnaya core across the western steppe