Genetics of Domesticated Behavior in Dogs and Foxes - Genetics and the Behavior of Domestic Animals - page 363

are more related to each other than to any other breed category selected for
different working tasks in Great Britain or other countries ( Parker et al.,
2004, vonHoldt et al., 2010 ).
The use of dogs for hunting is reflected in paintings and historical
records from ancient times ( Clutton-Brock, 1995 ). Although, we do not
have evidence that modern hunting breeds are descendants of these ancient
dogs, it is instructive to note that the sight hound breeds, perhaps the oldest
type of hunting dogs, are genetically closely related to each other
( vonHoldt et al., 2010 ), even those from different geographical locations.
Likewise, hunting breeds sharing highly specialized behavioral repertoires,
such as retrieving breeds, are more closely related genetically to each other
than to breeds such as scent hounds selected for different hunting skills
( vonHoldt et al., 2010 ).
It is well established that humans have deliberately preserved specific
valuable genetic variants in domestic animals from ancient times
( Andersson, 2009; Andersson et al., 2012; Rosengren Pielberg et al., 2008 ).
For example, all breeds characterized by the chondrodysplastic dwarfism
phenotype carry the same, identical by descent, FGF4 gene mutation ( Parker
et al., 2009 ) since prehistoric times. These dwarf breeds were developed in
different countries, at different times, and do not share recent common
ancestry ( Parker et al., 2004, 2007 ). For example, the Pekinese is an ancient
Chinese breed while Basset Hounds are traced back to Medieval Western
Europe. This FGF4 allele would clearly be disadvantageous for free-living
canids, and has been maintained in the dog population by artificial selection
favoring the phenotype.
To assume a similar scenario for behavioral traits is more difficult. In
contrast to some morphological and appearance traits that are often deter-
mined in dogs by a small number of genes with large effects ( Boyko et al.,
2010; Cadieu et al., 2009; Hoopes et al., 2012; Sutter et al., 2007 ), behavior
is most likely influenced by a large number of genes, each of which has a
relatively small effect on the trait ( Anholt and Mackay, 2009; Flint, 2003 ).
However, the close relationships among dog breeds with specific working
skills argues for the preservation of genetic variants for behavioral genes
among these breeds.
Selection for breed-specific behaviors in the course of breed development
was inevitably linked to selection for morphology, appearance, and other
characteristics that were important for the dog's ability to perform specific
tasks ( Coppinger and Schneider, 1995 ). Guard dogs had to have tough bodies
to fight enemies or predators. Sight hounds had to have gracile bodies and
high endurance for fast running and long hours of hunting. A white coat
color was favored by shepherds because it helped to distinguish herding dogs
from wolves ( Coppinger and Coppinger, 2001 ). A thick insulating coat was
important for dogs in many geographical regions in order to survive the cold
weather outside.