Fig. 4.
A schematic representation of the results of the fox domestication experiment.
- Left: a fox of the farm-bred population unselected for behavior. Foxes of this population show the typical aggressive response to human.
- Right: a fox of the experimental domesticated population. The dog-like behavior of foxes of this population is the result of many years of selection for tameability.
B – E: Activity of the HPA axis in farm-bred and domesticated foxes. Farm-bred foxes are shown in grey, the domesticated are in red.
B: Hypothalamic CRF (CRFmRNA/18SmRNA) and pituitary POMC (POMCmRNA/18SmRNA) gene expression, ACTH (pg/ml) and cortisol (μg/dl) level in farm-bred and domesticated foxes.
C: Age-related changes in plasma cortisol level in farm-bred and domesticated foxes: 1) farm-bred foxes with aggressive response to human, 2, 3) foxes of the domesticated population with low (2), and high (3) domestication scores.
D: Total time of locomotion, an indicator of exploratory behavior, and plasma cortisol level in farm-bred and domesticated foxes at the age of 1-2 months: locomotion is plotted on the graph; plasma cortisol level is represented as bars.
E: Plasma cortisol in silver foxes during pregnancy and lactation.
F – J: Dog-like morphological changes arisen in foxes of the domesticated population:
F: Similarity of coat depigmentation between dogs and foxes: Left, a border collie; Right, a tame fox.
G: Tail carriage, curly tail: Left, an Islandsk Farehund; Right, a tame fox.
H: Ears are floppy and face skull is widened in some pups of tame foxes: Left, a pug; Right, a tame fox pup.
I: Long jaw (elongation of the lower jaw) in the English bulldog occurs among tame foxes: Left, an English bulldog; Right, a tame fox.
J: Elongation of face skull in certain dog breeds and tame foxes: Left, a Pharaoh hound, Right, a tame fox.