Researchers have used DNA analysis to discover that there have been wide variations in the prevalence of complex leopard spotting in horses over the millennia, including since the start of domestication.
The international research project, led by scientists at the German Leibniz Institute for Zoo and Wildlife Research, analysed 96 archaeological bones and teeth of horses originating from the late Pleistocene to Medieval times.
They found that although a considerable number of domestic horses from the early Bronze Age (2700BC to 2000BC) were genetically identified with leopard spotting complex, the coat colour seemed to have almost disappeared at the end of this period.
One reason might have been that homozygous animals were night-blind, in addition to the white coat colour. The ability to see is important for communication, orientation, the search for food and avoiding predators. Therefore, night-blind animals barely had a chance to survive in the wild. In human care, night-blind horses are described as nervous and timid, and can be difficult to handle at dusk and darkness.
About 1000 to 1500 years later the leopard complex again occurred increasingly, they found.
The coat colour was reintroduced into the domestic gene pool from numerous wild animals existing in those days.
After the Iron Age a renewed upswing in leopard complex spotted horses was reported.
“The behaviour of breeders and their preferences changed at that time, as it does today,” said Arne Ludwig from the Leibniz Institute, who led the study.
The changing interests in leopard complex spotted horses can also be recognised in Medieval times, where they enjoyed a high reputation, as paintings and text samples demonstrate.
They were among the favourite animals of the nobles and were considered symbols of chastity.
They were also favoured in the Baroque period before they appeared to go out of fashion again.
Today, spotted coat patterns occur in many breeds and breeders have shown an increasing interest in recent years.
”If the theory of the alternative selection applies then it can explain how genetic diversity in domestic populations could be preserved in spite of relevant selection for or against a certain characteristic,” Ludwig said.
“The problem in breeding nowadays is that we cannot go back to the appropriate wildlife species, because they are simply eradicated or the wild types vanished by selection.
“This has to be evaluated negatively for the gene pool of today’s domestic animal breeds. The missing genetic diversity highly restricts the possibilities of breeding in the future.”
Pictured, from left:
(a) the panel of the dappled horses —‘Le panneau des Chevaux ponctue´s”, Cabrerets, Lot France (Photo from P. Cabrol, Centre de Pre´histoire du Pech Merle).
(b) There are several examples of spotted horses in the art of ancient Egypt dating from 1500 to 1300 BC.
(c) The mosaics from North Africa are from the Dominus Iulius at Carthage. (d) This Persian plateau was passed from conqueror to conqueror until the arrival of the Muslims from the South in 640 AD. Persian art objects from that time to the present show spotted horses, suggesting that spotted horses were common in Persia since before the Muslim conquest. © Spanish Jennet Horse Society
(e) Chinese horse sculptures dating to 600–900 AD.
(f) The mosaic (Spain 975 AD) is from the Beato de Gerona Codex, dating to 975 and attributed to the Abad Domenicus.
(g) The famous eighteenth century painting from John Wootton titled “Lady Conaway’s Spanish Jennet” is owned by the Marquees of Hertford.
(h) A modern Knabstrup horse from the famous horse breeding farm ‘From schu¨tzenden hand’ (Werpeloh, Germany) showing leopard complex spotting. © Thomas Hackmann
Pictures show horses at Earina Appaloosa Stud.
Ludwig A, Reisman M, Benecke N, Bellone R, Sandoval Castellanos E, Cieslak M, Fortes GG, Morales-Muñiz A, Hofreiter M, Pruvost M (2014): 25,000 Years fluctuating selection on leopard complex spotting and congenital night blindness in horses. PHIL TRANS R SOC B 20130386;http://dx.doi.org/10.1098/rstb.2013.0386.