Behavioral Genetics and Animal Domestication - Genetics and the Behavior of Domestic Animals - page 45

Over the last decade or so, researchers have started to investigate the
specific adaptive properties of domesticated behavior. In particular, the
cognitive and communicative abilities of dogs have received a large amount
of attention. In general, dogs have developed traits which are absent in
wolves, and which make them more suited to interacting and communicating
with humans ( Miklosi, 2008 ). For example, they are better at responding to
human cues such as pointing and gazing, and they can learn and understand
large numbers of spoken words and put these into categories. This probably
represents exceptional adaptations in a species, which has been selected for
many thousands of years for their ability to cooperate and interact properly
with humans, but it demonstrates that the specific selection pressures under
domestication may lead to novel adaptations within a limited evolutionary
time. The extent of this adaptation is further shown by the fact that dogs,
when released of the human selection (such as during feralization and in
stray dogs), wolf-like social behavior does not re-emerge. Free-ranging dogs
have a very different social and reproductive system than their wolf ancestors;
they mate promiscuously and all individuals reproduce (unlike in wolves,
where normally only one pair in a pack raises offspring) and they do not form
highly cooperative, stable packs ( Boitani and Ciucci, 1995 ).
A widely discussed problem is how many genes are actually involved in
causing the domesticated phenotype. It has been suggested that the reoccur-
rence of similar phenotypic changes in many different domesticated species
could be indicative of a limited number of “master genes”, perhaps only one,
controlling a range of traits ( Stricklin, 2001 ). As selection acts on this gene,
for example by reducing stress and flightiness, several or all of the domesti-
cated phenotypes would develop as correlated responses.
An important study sparkling suggestions such as these, is the one carried
out by Belyaev and co-workers in Russia during the 1960s ( Trut, 1999 ). They
selected farm foxes (silver foxes, descendants of the red fox) for tameness in a
simple test, measuring the propensity to flee or attack when approached by the
hand of an observer. The response in the selected trait was rapid, and within
a few generations, the selected foxes were tame and behaved in a dog-like
manner towards humans.
Interestingly, several other domestication-related traits increased in fre-
quency among the tame foxes. This included loss of pigmentation, faster onto-
genetic development, curly tails, floppy ears, and compressed jaws. Belyaev
himself suggested that this may have been the result of a released selection
pressure on many genes, controlled by one or few “master genes” which were
directly selected upon ( Trut, 1999 ).
Similar results were found in an experiment where the Belyaev approach
was used to select rats of high and low fearfulness towards handling. The
tamer rats had a generally dampened stress response, as shown in both physi-
ological and behavioral variables ( Albert et al., 2008 ). However, even though
several genetic loci seem to affect more than one of

the phenotypic