European wild horse colour phenotypes

Back in 2013, I did an illustration of the five colour phenotypes found in European wild horses according to genetic research and presented it in a post (back in the time when I called the European wild horse "tarpan", which I nowadays do not). I also put it on Wikipedia, but it was removed by some know-it-alls editing the German page. 

I recently did an updated version of that illustration. Back in 2013 I considered it likely that the European wild horse had a falling mane, which I no longer do (see here). I corrected it, and here is the result: 

It shows all the colour phenotypes confirmed for Equus ferus ferus so far, including: bay dun (top left), bay + nondun1 (top right), black dun (middle left), black + nondun1 (middle right), leopard spotted (bottom). For the references for the colour phenotypes see [1,2]. Black and black dun are caused by the allele a, which became the dominant allele later in the Holocene (whether the phenotype is black or black dun depends on the alleles on the Dun locus) [3], while Pleistocene horses all had the A+ allele, and thus were either bay or bay dun. A 2015 study [4] examined the alleles on the dun locus in a late Pleistocene (42.700 years old) wild horse from Russia and that of a 4000 years old horse (also from Russia). It turned out that the Pleistocene wild horse was heterozygous for dun and nondun1, thus had a dun phenotype. And since all wild horses from that time were A+//A+, it must have been bay dun and thus looked like the drawing at the top left. The 4000 years old horse (whether it was a wild horse or domestic horse was not tested), was homozygous for nondun1. Thus, if it was a wild horse, it looked like the illustration at the top right, since the a allele was not found in Russian samples. 

I also gave the leopard spotted wild horse a dark neck and face, matching the cave art (see here). 

Literature 

[1] Pruvost et al.: Genotypes of predomestic horses match phenotypes painted in paleolithic works of cave art. 2011

 [2] Ludwig et al.: Coat color variation at the beginning of horse domestication. 2009.

[3] Sandoval-Castellanos et al.: Coat colour adaption of post-glacial horses to increasing forest vegetation. 2017

[4] Imsland et al.: Regulatory mutations in TBX3disrupt asymmetric hair pigmentation that underlies Dun camouflage colour in horses. 2015.