Genetics of Domesticated Behavior in Dogs and Foxes - Genetics and the Behavior of Domestic Animals - page 383

wolves underwent natural selection for behavioral traits that allowed them to
coexist with humans. Genetic variants pre-existing in wolf populations were
likely targets of this selection. Support for this theory of selection for pre-
existing variants also arises from recent studies of size in dogs. While all
small breeds of dogs are fixed for a specific variant of the IGF1 gene
( Sutter et al., 2007 ) the same allele was found to segregate in a modern
population of gray wolves from the Middle East ( Gray et al., 2010 ) and
in Portugese Water dogs, a breed in which the size variation takes place
( Chase et al., 2002 ).
Identification of loci that both influence tame behavior in foxes and are
homologous to regions in the dog genome supporting genetic signals related
to selection of dogs from wolves leads to the intriguing hypothesis that
domesticated behavior in dogs and foxes may have similar genetic bases.
Not only do dogs differ in their behavior from wolves, but different
breeds of dog are characterized by genetically determined differences in
behavior. Although the latter differences are highly characteristic and read-
ily recognized, in fact each such behavioral pattern likely represents a
synthesis of many discrete behaviors. This synthesis has been clearly demon-
strated in the fox study. For example, the apparently simple response to
human presence can be influenced by many behavioral characteristics at
once: interplay of discrete mechanisms captured by the tame aggressive
(PC1) and bold

shy (PC2) dimensions are just two of the most obvious ones
that influence the test outcome. However, a detailed understanding of the
genetic basis of behavior in dogs requires well-defined phenotypes, as well
as control of environmental factors and gene

environment interactions
that can strongly influence behavioral outcomes. These are not as easily
implementedasinthefoxstudy.
Although domestication has, for many years, been of great interest to
scientists, most notably including Darwin, until recently basic questions con-
cerning the genetic mechanisms involved have been difficult to address.
With modern advances in molecular genetic technologies, however, it is now
feasible to pursue research on diverse organisms to find the links between
genes, brain function, and a wide range of social behaviors ( Robinson et al.,
2005, 2008 ).
We expect that identification of the molecular mechanisms underlying
domesticated behavior in foxes and dogs will help us to understand basic
biological principles guiding social behavior in mammals and to provide
insights into our own behavior as well.

ACKNOWLEDGMENTS

We thank Dr. K. Gordon Lark, Kevin Chase, and Anastasiya V. Kharlamova for insightful
discussions and to Dr. Lark for critical reading of the manuscript. We would like to
express profound gratitude to members of Dr. Trut, Dr. Acland, and Dr. Kukekova's