Coat Color Variations and Tameness in English Shepherds: A Hypothesis on the Role of Pleiotropy in Domestication


In English Shepherds, coat color changes could be a result of selection for tameness through a process similar to the one observed in Belyaev’s silver fox experiment. The underlying genetic mechanism may involve pleiotropic effects, where certain genes influence both tameness and coat color.


The English Shepherd is a versatile herding dog breed known for its intelligence, adaptability, and loyalty. Over time, breeders have selected these dogs for specific behavioral traits, such as tameness, to make them better companions and working partners. As a result, it is plausible that the selection for tameness has inadvertently led to coat color changes in this breed.

Proposed Mechanism

It is possible that the genes responsible for tameness in English Shepherds are pleiotropic, meaning they also have an effect on coat color. This would suggest that selecting for tameness has inadvertently concentrated the genes influencing coat color, leading to a greater variety of coat colors in the population over time.

Supporting Evidence

Belyaev’s silver fox experiment showed that selecting for tameness resulted in correlated changes in physical traits, including coat color, due to pleiotropic effects. Similar genetic mechanisms might be at play in the domestication and breeding of English Shepherds.

Further Research

To test this hypothesis, genetic and phenotypic data from English Shepherds could be analyzed to investigate potential associations between tameness-related genes and coat color genes. If a correlation is observed, it would strengthen the argument that selecting for tameness has indirectly influenced coat color variations in this breed.


Understanding the genetic basis of coat color changes in English Shepherds could provide valuable insights into the broader process of dog domestication and breeding. Moreover, it could help breeders make more informed decisions when selectively breeding dogs for specific traits, by considering the potential pleiotropic effects of the genes involved.

Further reading

Tony Bierman, “Coat Color Transformations and Tameness: Unraveling the Genetic Link Through Selective Breeding in Silver Foxes,” OBTESA, Accessed April 3, 2023,

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Tony Bierman, "Coat Color Variations and Tameness in English Shepherds: A Hypothesis on the Role of Pleiotropy in Domestication," OBTESA, Accessed June 18, 2024,