A lot of changes arose in Spanish mtDNA after the Neolithic. mtDNA sequenced from Iron age Spain indicates those changes had occurred by circa 300 BC.
Modern and Spanish mHG frequencies are included in the following spreadsheets along with mHG frequencies of other ancient and modern Europeans…Spain
JT, N1, U5
For convenience here is a picture comparing modern and ancient Spanish mHG frequencies. mHGs with significantly different frequencies in modern and ancient Spain are highlighted....Notice Iron age Spain is similar to Modern
The two mHG which differ in frequency the most are H and K.
Neolithic Spain had a whopping 27-30% K and an unimpressive 20-25% H. Modern and Iron age Spain has/had a whopping 40-45% H and an unimpressive 7% K.
mHG frequencies in modern Spain are basically indistinguishable to mHG frequencies in most of modern Europe. mHG frequencies in Neolithic Spain were basically indistinguishable to mHG frequencies in Neolithic Germany and Hungary.
The same mtDNA changes which occurred in Spain after the Neolithic occurred in much of Europe. I think a mixture of migration from “Asia”(inclu. mostly “Eastern Europe”) and natural selection caused(I gave my reasons in this post) those changes to occur.
Furthermore there are many mHGs which exist in modern Spain at over 1% or just under 1% but haven’t been found in Neolithic Spain yet…..
L(xM, N): Modern Spain(2%), Neolithic Spain(0.5%)
M1: Modern Spain(0.7%), Neolithic Spain(0%)
N1b1: Modern Spain(0.5%), Neolithic Spain(0%)
R1: Modern Spain(0.3-0.5%), Neolithic Spain(0%)
U6: Modern Spain(2%), Neolithic Spain(0%)
U5a: Modern Spain(2-3%), Iron age Spain(4%), Neolithic Spain(0.5%)
U8b1, U8a1a: Modern Spain(0.5-1%), Neolithic Spain(0%)
U9a: Modern Spain(0.5%), Neolithic Spain(0%)
T1a: Modern Spain(1.5-2%), Iron age Spain(2%), Neolithic Spain(0%)
T2c1: Modern Spain(1-1.5%), Neolithic Spain(0.5%)
I: Modern Spain(2-3%), Neolithic Spain(0%)
H6: Modern Spain(1-2%), Neolithic Spain(0%)
HV6-24: Modern Spain(1.5-2%), Neolithic Spain(0%)
W: Modern Spain(1%), Iron age Spain(6%), Neolithic Spain(0%)
U6, L(xM, N), and M1 indicate modern Spanish have maternal ancestry from Africa which Neolithic Spanish did not have. The L(xM, N) mHGs modern Spanish belong to are mostly the same L(xM, N) mHGs NorthWest Africans belong. The two most common L(xM, N) mHGs in both locations are L1b and L2a1. The single L(xM, N) from Neolithic Spain belonged to L1b.
The other mHGs don’t conclusively indicate maternal ancestry from any particular region. U5a, T1a, T2c1, I, R1, W, HV6-24, and H6 are all present in ancient mtDNA from Central and Eastern Europe at high frequencies. It’s possible that region lent Spain those mHGs. But I and T1a are also frequent in the Middle East.
Along with differences there are also noticeable similarities between Neolithic and Modern Spanish mtDNA. Both have a higher frequency of J2b1a, J2a1a, T2a1b, U5b, U5b3, and U5b1i than ancient and modern Europeans from other regions.
Nuclear DNA confirms considerable genetic changes took place in Spain after the Neolithic age. Here’s how modern Spanish come out when they’re modeled as a mixture of Neolithic Spanish and other ancient and modern humans.
Middle Neolithic Spain: 48%
Eastern Europe(Yamnaya): 24%
Near East(Cypriot): 22%
So nuclear DNA Spain probably received migration from Eastern Europe(Yamnaya), the Near East(Cypriot), and Africa(Mozabite) after the Neolithic. mtDNA is pretty consistent with this.