Introduction
Dmitry Belyaev, a Russian geneticist, conducted a long-term experiment on the domestication of silver foxes (Vulpes vulpes) that demonstrated how selecting for tameness could result in a number of correlated changes, including coat color changes.
Starting in the late 1950s, Belyaev and his team selectively bred silver foxes, choosing only the tamest individuals to reproduce. They focused on choosing foxes that showed less fear and aggression towards humans. Over time, they observed that not only did the foxes become increasingly tame, but other traits also emerged, such as floppy ears, shorter snouts, and curly tails. Additionally, changes in coat color began to appear, with some foxes exhibiting piebald patterns and others having a lighter or star-patterned coat.
Pleiotropy
These correlated changes are thought to be linked to the pleiotropic effects of certain genes. Pleiotropy occurs when a single gene influences multiple traits. In the case of the silver fox experiment, it is believed that the genes responsible for tameness were also associated with the genes influencing physical traits, such as coat color. This phenomenon is known as the “domestication syndrome” and has been observed in other domesticated animals as well.
Rapid Changes
It is quite remarkable that the associated phenotypic changes emerged in just a few generations. Belyaev’s silver fox experiment demonstrated how rapidly selective breeding can alter an organism’s genetic makeup and produce significant changes in its physical and behavioral traits.
The experiment began with foxes that were initially bred for their fur, with little regard for their tameness. However, when Belyaev and his team started selectively breeding the foxes specifically for their tameness, noticeable changes in behavior and appearance emerged quickly. Within just 20 generations, the researchers observed the emergence of foxes that were far more docile and friendly towards humans than their wild counterparts.
The speed at which these changes occurred can be attributed to the strong selection pressure that the researchers applied. By choosing only the tamest individuals to reproduce, they effectively concentrated the genes responsible for tameness in the population. As a result, each subsequent generation exhibited a higher frequency of these genes, leading to the rapid emergence of other associated traits.
This phenomenon is a testament to the power of artificial selection and provides a fascinating example of how human intervention can quickly shape the evolution of a species. The silver fox experiment has been widely recognized as a significant contribution to our understanding of the genetic basis of domestication and the complex interplay between genes and traits.
Conclusion
Belyaev’s experiment provided valuable insights into the process of animal domestication and the genetic changes that can occur when selection is focused on a specific trait. It highlights the complex relationship between genes, traits, and the process of domestication.
Further reading
- “How to Tame a Fox (and Build a Dog): Visionary Scientists and a Siberian Tale of Jump-Started Evolution” by Lee Alan Dugatkin and Lyudmila Trut (2017). This book provides an in-depth look at Belyaev’s silver fox experiment and its implications for our understanding of domestication and evolution.
- “The Genetics of Domestication” by Carlos A. Driscoll, David W. Macdonald, and Stephen J. O’Brien (2009). This article, published in the journal ‘Annual Review of Animal Biosciences,’ reviews the genetic basis of domestication and the mechanisms that drive the process.
- “Genetics and the Behavior of Domestic Animals” edited by Temple Grandin and Mark J. Deesing (2014). This book explores the genetic basis of animal behavior and the role of genetics in domestication, with chapters on various species, including dogs, cattle, and poultry.
