Genetic Heredity:
In the course of its evolution, the Bergamasco Sheepdogs have acquired specific characteristics which made them unique in appearances and functions. Those fundamental traits made them successful at the task them were mean to achieve.
Thanks to Dr. Maria Andreoli’s in-depth work on the genetics of the Bergamascos, clarity and explanation of the standard has been achieved. Below are results of these researches explaining the evolution, genetics and standard of the Bergamasco color.
A- Genetic sequence of Locus in the Bergamasco Sheepdog:
The only accepted color in this breed is solid black. Neither brown, sable, tawny nor the black spotted. The genetic table of the Bergamasco breed is represented as follow:
As B C D E G M S t
g m
As: all over dark, produces black without any tan on the dog (agouti series)
B: in single or double dose, allows the production of black pigment (brown series)
C: allows full expression of whatever pigment is prescribed by other genes. (albino series)
D: full intense pigmentation, D in combination with B is black (dilution series)
E: extension of the dark pigment, preventing masking and brindle in conjunction with A (extension series)
G and g: graying of the coat : G, not graying: g (graying series)
M and m: M is merling and m is uniform coloring (merle series)
S: white spotting (tips), mostly as puppies (white spotting series)
t: lack of ticking (ticking series)
Bergamascos are strictly AsAs EE (solid dark) and BBDD (Black). However, adult individuals completely black can rarely be found, this being to the presence of two genes, which with multiple mechanisms change the color of the coat towards the grey: such genes are G and M.
The white is accepted only as small spots to the chest, at the tip of the feet and sometimes on the tip of the tail. Those are clearly visible in the young puppies, but they shrink or disappear in the adult dog. Therefore they are SS (The dominant allele S, means solid color. Most dogs that are homozygous for S (SS) have no white hair at all, or possible a tiny amount e.g. a white tail tip).
At birth, the Bergamasco puppies can only be solid black or grey with black markings (Merle).
1- Black: As C D E g m S t
The puppies with this genetic sequence, as well as adults, do not change their coat color (because of allele g).
A good majority of puppies born black however, develop a progressive lightening of the coat during growth, together with the black hairs, other more diluted colors, such as grey, black with white points and/or bands or completely white hair. The presence of hair of such diverse variation is a coat in any gradations of grey, from the grey anthracite to the lightest of grey.
Such effect is due to the presence of the allele G. The wide range of the gradations of grey, makes difficult the interpretation of the relationship between G and g.
Surely it is not absolute relationship of complete dominance, but more likely of an incomplete dominance, so that the homozygote GG and the heterozygote Gg can have different gradations of lightening.
Also the presence of modifying polygenic systems or the concomitant action of genes of other locus strengthen or decrease the effect produced by the allele G.
What is certain from experienced breeding is that in some individuals the tendency to the varied changes of the color of the coat, from black to grey is transmitted hereditary, but the extend of the tendency of change cannot be pre- determine.
The dogs born black who present grey coats as adults have the following genetic sequence:
As B C D E Gg m S t or As B C D E GG m S t
2- Grey with black markings (merle):
As B C D E gg Mm S t or As B C D E Gg Mm S t or As B C D E GG Mm S t
Two alleles can be present in the case of merle: m responsible for uniform coloring and M responsible for lightening of the black coat.
The M gene is dominant over m . The heterozygote allele combination Mm determines a coat in which the back color black comes in part diluted to grey, not in an uniform and complete manner, so there are also “black” undiluted. The result is a grey coat with black markings.
In this type of heterozygote combination, the effects of such allele limit themselves to a partial decrease of pigmentation of the coat and does not involve nor the pigmentation of the eyes, nose nor of the rhymes of the eyelids and lips.
On the other hand, homozygote pairing (MM) has much different effects. In these individuals the lack of the pigmentation is massive. Multiple large white markings appear on the coat, while the black almost completely disappear, the result is a grey coat with white markings. One or both eyes are blue, the nose is all or partially pink and the rhymes of the lips and eyelids present considerable zones of de-pigmentation. In addition to these obvious outwards signs, the hearing system is often defective, with partial or total deafness and many individuals are sterile, particularly bitches.
Obviously breeders must be careful not to produce individuals homozygote of the gene M. In other words breeders should avoid the couplings between subjects both heterozygote (Mm), since in such case 25% of the puppies would be homozygote (MM).
The best pairing combination is a homozygote "mm" partner born solid black (they do not carry the "M" gene responsible for the patching and grey coat) with a heterozygote Merle "Mm" (a grey with black patches). This pairing will result in a litter in which 50% of the puppies are black (mm) and 50% grey with black markings (Mm).
B- Bergamasco Color and it’s genetics
Bergamascos are either born solid color (often we call these dogs black, even though they can be all grey later in life) or Merle (patched grey/black).
1- List of principal Genes responsible for the Bergamasco Color:
a- Genes "M" and "m":
these genes pair together in either of the following combination: MM or mm or Mm.
Description:
•
“M” : is a gene responsible for a light color of the coat (lightening to a grey hair) in part of the body, this M gene is dominant over “m” gene (it means that if both gene are present the result will be M only). The “M” gene is only found in Merle dogs.
so a merle dog is only Mm or MM
If the dog gene pair is “ Mm”, the dog is merle (with part of the coat patched of light color), The body is grey with black patches (either light grey with large black patches or dark grey with small black spots).
• “m” : this gene is responsible for a uniform coloring (solid all over the body), the “m” gene is recessive over “M” (it means that in the case of a pair Mm, you cannot see the result of the gene m).
When the dog gene pair is “ mm”, the dog is in a uniform color. These dogs are born solid black (with an occasional white patch).
Some of the black puppy stays black as they mature while some become solid grey as they get older (right puppy on picture below wsa born black, left puppy was born and remained merle):
b- Genes "G" and "g":
these genes pair together in either of the following combination: GG or gg or Gg.
Description:
“G” : is a gene which determines a progressive lightening (or graying) of the coat color during the dog’s life (more obvious in dogs born black which later turn grey, See picture above of Onyx)
“g” : is gene which guarantees the persistence of deep black coat color (present at birth, see picture above of Brio).
2- Detailed explanation on Merle Color, Black color impact of gene “M” and “m”:
a- Merle (the correct merle has a genetic pair Mm):
The merle color is of particular importance in the Bergamasco Breed.
The dogs with the merle gene have normal pigmentation of eyes, nose, lips (no pink nose or lips , no blue eyes).
The body is grey with black patches (either light grey with large black patches or dark grey with small black spots).
Genetically these dogs are called "heterozygote with a Merle gene pair “Mm”.
"hetero" means "different", so the pair of gene they have is made of 2 gene (one from each parent) that are different . One is "M" from one parent and the other is "m" from the other parent.
The dogs carry a dominant gene “M” (responsible for the lightening of the coat in part or most of the body) and a recessive (not dominant) “m” gene (responsible for a uniform coloring). But since "m" is recessive to "M" these dogs do not have a uniform coat, but do carry the gene.
b- Solid color also called black (the black or uniform color puppy has a genetic pair mm)
These dogs have normal pigmentation of eyes, nose, lips (no pink nose or lips , no blue eyes).
The body is solid at birth (sometime a small white patch) and can stay black or turn solid grey or Isabella as they age.
Genetically these dogs are called "homozygote with a gene pair “mm”.
"homo" means "same", so the pair of gene they have is made of 2 gene (one from each parent) that are the same . One is "m" from one parent and the other is also "m" from the other parent.
c- Breeding choices:
• The best pairing combination for breeding is a homozygote "mm" partner born solid black (they do not carry the "M" gene responsible for the patching and grey coat) with a heterozygote Merle "Mm" (a grey with black patches). This pairing will result in a litter in which 50% of the puppies are black (mm) and 50% merle, grey with black markings (Mm).
As these merle puppies grow up, they remain the same color as at birth with little variation in the grade of grey, while the black markings can either remain unchanged or tend towards a dark grey.
• Also if two homozygots (2 black dogs) are bred together (two dogs with mm, one can be all black as an adult and the other can look grey but was black at birth so it is still a black dog), the result will be 100% black puppies, see graphic:
This combination is also correct but if two black individuals "mm" are bred, the litter would be 100% black and the merle M gene would be lost.
Note that, in the dogs which are born black, only a few retain this color while most will gradually change to grey due to the growth among the black hairs of goat hair (grey or white ones). The presence of hairs in such a variety of tones creates an overall coat color in all grades of grey from darkest to lightest, while the dogs is still considered black.
d- incorrect Merle (the incorrect merle has a genetic pair MM):
If two merle individuals are bred, the litter will produce 25% of puppies with an homozygote for the gene Merle (MM).
Those individuals will present white patches all over the coat, one or both eyes are blue and there are pink spots on the nose tip and on the edges of the eyelids and lips. Apart from these undesirable outward signs, the hearing system is often defective and many specimens, particularly bitches, are sterile.
Such characteristics are considered faults in the Standard.
Obviously, breeders have to be very careful to avoid producing dogs with hereditary tares.
The color of a genetically balanced litter is 50% Black 50% Merle and come from a merle parent and a black (or solid color) parent, but an all blak litter from two black parents is also correct:
3- Detailed explanation on mpact of gene “G” and “g”:
Of the dogs that are borne black, only few retain this color; the others in which the graying factor “G“ is present, will become lighter. The "G" gene determines a progressive lightening (or graying) of the coat color during the dog’s life (more obvious in dogs born black).
It is important to emphasize that the graying must not be interpreted as the effect of de-pigmentation. It is the result of interchanges between the dermas and the matrix of the hair.
In the days when Bergamascos had more of a functional task, selection was carried exclusively on the basis of the characteristics most suited to the work which the dogs were expected to carry out and the environment in which they worked. Some of the reasons of the tendency to favor the lighter coats are logical with the work expected of the dogs:
• Black attracts sunrays so black coated dogs would suffer in their environment and have diminished resistance.
• Black dogs stand out too much amongst the grey sheep they watched, which could frighten them as well as make it too easy to see for preying animals and thieves.
(Puppy on the right was born black, at 5 month the G gene lightened the coat to solid grey)
Whatever the reason, the ancient shepherd preferred a color which blended best with a mountainous background typical of alpine pastures.
This explains why they kept the black population small and selected dogs which often lightened up thanks to the “G“ gene as better working dogs.
It is of fundamental importance to preserve both the “M” and “G“ genetic factors if not to loose the authenticity of the Bergamascos.
Unfortunately today , because of poor breed management, merle dogs and light grey “black “dogs are sometimes not used for breeding purpose and due to prejudice or insufficient knowledge of the graying effect produced by “G“, it has been interpreted as pigment deficiency and undesirable.
This is very serious error since this factor was most common among the sheepdogs and completely black coats were practically unknown.
The black on black breeding geared to produce only "dark black" indivuduals (without the graying gene) G and selections is based on superficial generalizations have no theoretic foundation and can be extremely dangerous. It is only profound knowledge of the breed characteristics and background history which can preserve the typical traits of the Bergamascos.