Behavioral Genetics and Animal Science - Genetics and the Behavior of Domestic Animals - page 4

their hormone profiles and the monestrous (once a year) cycle of reproduc-
tion was disturbed. The tame foxes would breed at any time of the year.
Furthermore, changes in behavior occurred simultaneously with changes in
tail position and ear shape, and the appearance of a white muzzle, forehead
blaze, and white shoulder hair. The white color pattern on the head is similar
to many domestic animals ( Belyaev, 1979 )( Figures 1.1 and 1.2 ). The most
dog-like foxes had white spots and patterns on their heads, drooping ears,
and curled tails and looked more like dogs than the foxes that avoided
people. The behavioral and morphological (appearance) changes were also
correlated with corresponding changes in the levels of sex hormones. The
FIGURE 1.1 Wild-type fox before Belyaev started selective breeding for tameness. Reprinted
from Journal of Heredity by permission of Oxford University Press.
FIGURE 1.2 Selecting for tameness for many generations altered the body shape and coat
color pattern. Foxes selected for tameness resembled dogs. Reprinted from Journal of Heredity
by permission of Oxford University Press.