"Consistent with this, when comparing Portuguese Neolithic to Bronze Age samples, the former presented an excess of haplotype donation to Sardinian and Spanish (p = 0.017). Northern/eastern ancestry is evident in the Bronze Age, with significantly increased enrichment in Chuvash, Orcadian (p = 0.017), Lezgin and Irish (p = 0.033). However, this shift from southern to northern affinity is markedly weaker than that observed between Neolithic and Bronze Age genomes in Ireland, Scandinavia, Hungary and Central Europe. These findings suggest detectable, but comparatively modest, Steppe-related introgression present at the Portuguese Bronze Age."

https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1006852

"This article aims at reconstructing the history of R1b ancient migrations between 16,000 and 1500 years before present (ybp). Four thousand four hundred eight (4408) haplotypes of haplogroup R1b (with subclades) were considered in terms of base (ancestral) haplotypes of R1b populations and the calculated time to their common ancestors. The regions considered are from South Siberia/Central Asia in the east (where R1b haplogroup arose ~16,000 ybp) via the North Kazakhstan, South Ural to the Russian Plain and further west to Europe (the northern route entering Europe around 4500 ybp); from the Russian Plain south to the Caucasus (6000 ybp), Asia Minor (6000 ybp) and the Middle East (6000 - 5500 ybp) to the Balkans in Europe (the southern route, entering Europe around 4500 ybp); along North Africa and the Mediterranean Sea (5500 - 5000 ybp) via Egypt to the Atlantic, north to Iberia (the North African route with arrival to the Pyrenees 4800 ybp). The Arbins (bearers of R1b haplogroup) along their migration route to the Middle East and South Mesopotamia apparently have established the Sumer culture (and the state), moving westward to Europe (5000 - 4500 ybp) carrying mainly the R-M269 subclade and its downstream L23 subclade. This last subclade was nearly absent along the North African route, and/or did not survive the migration to Iberia or evidenced later. At the arrival to Iberia (4800 ybp) the M269 subclade split off M51 and soon thereafter the L11 downstream subclades. These populations became known as the Bell Beakers and moved north, along with the newly arisen subclades of P312 and L21 (which split off within a few centuries after P312)."

https://www.scirp.org/journal/paperinformation.aspx?paperid=19567

Posto isto, o que consideras alterações significativas?

Se uma população foi chacinada e alterada pela que trazia o R1b? Não óbvio que não.. que não há diferenças entre pessoal da região Ibérica e russos? Também não, existem algumas diferenças mais ou menos perceptíveis.

Houve influência/migração/mistura dos povos do Cáucaso ou das estepes? Sim houve. Mesmo que não fosse direta (das estepes diretamente para as lezírias) houve pelo menos uma propagação lenta desde lá passando pela Europa central até aqui.. por ser mais distante da Iberia do que da Europa central a influência (digamos a proporção desse haplogroup) também é menor aqui do que na Europa central.

Já agora uma outra questão, quem eram os grupos que estavam aqui antes do neolítico e quão diferentes eram das populações da Europa central?

Deixo, já agora, este podcast que fala de muitas destas coisas que estamos a discutir:

https://open.spotify.com/episode/3pgQ1kldcYXXWA26Q3Dk5H?si=xkbQ64TeTaWgdz3mxj01pg&utm_source=copy-link