Striping patterns in domestic horses

Abstract

1. Striping is distributed among very diverse breeds of domestic horses. It is found more frequently and more dictinctly expressed among primitive, local populations of horses than among standard breeds, due to continued selection against wild coat colors (wilddun, mouse-gray), with which striping is correlated in some way, as yet insufficiently elucidated. 2. Striping in domestic horses in most cases resembles in structure striping in all other species of the familyEquidae (zebras, asses, hemiasses, wild horses) and is by its very nature rudimentary and atavistic (Darwin). The most persistent elements of striping in domestic horses are: the spinal stripe, next horizontal zebroid stripes on the legs, then rudiments of stripes on the vertical system (shoulder stripes and spots); rarely there has been observed the development of arch-shaped stripes on the forehead (Darwin, Ewart, Krieg). 3. A study of variation in such atavistic striping in different breeds of horses throughout the world has made it possible to distinguish two chief types of striping, differing from each other in the structure and localization of the stripes of the vertical system and also in several specific features in the structure of the spinal stripe and the zebroid striping on the legs. The first type of striping (Figs. 1–5) is most clearly expressed in small local breeds of European horses (Ewart'sforest type or thenorthern group of Russian authors), but it is also encountered among horses of thesouthern group (eastern type ofFranck) and heavy western horses. The second type (Figs. 6–16) is characteristic of horses of the Mongolian group and is not found beyond the limits of the latter's influence. 4. In addition to atavistic striping in domestic horses, there occurs in very rare cases, striping of a brindling pattern (Figs. 17a, b), which does not possess the characteristic structural features of striping inEquidae and which — like brindling in cattle (Fig. 18) and dogs — must be regarded as a „new formation” of mutational origin.