Popular sire syndrome:
Breeders and genetics are trying to avoid popular sire syndrome. At the same time, the most common advice given by breeders is “knit the best with the best.”
This is a paradoxical situation with a predictable consequence: the “best” dogs are the dogs with the highest demand; therefore such males give the largest number of offspring and becomes popular sires.
The popularity of popular males:
As far back as 100 years ago, Williams Haynes (1915) wrote about the “influence of the popular sire,” noting that in the three terrier breed he studied – Irish Terrier, Scottish Terrier and Fox Terrier – about 40% of the puppies were descendants of only 20% of males.
In those days, “popularity” was completely different than now – the “prolific” gave 5-7 litters, which in our time is a very small amount. Surprisingly, Heinz believed that popular breeders were beneficial to the breed by maintaining the diversity in the breed.
At first glance, it may seem that if every year about 40% of puppies are born from 20% of sire males, then, in the end, this will lead to greater uniformity in the breed. However, this is not always the fact. Not only can it shrink the gene pool of a breed, inbreeding quotient will definitely increase, in time.
The selected breeders are more or less exceptional animals, but their selection does not have a uniform system. Most of them have superiority in some specific physical indicators, but they do not have superiority in the same indicators or equally, and even with no equal situations or directions.
Personal schemes work here, ideas about the ideal of various breeders, as a result, a small number of different types of breeders give a large number (above average) offspring, disrupting the average for the breed in the next generation and introducing an abnormal amount of variation.
The fact, that artificial breeding gives a small number of selected diverse breeders the possibility of unduly influencing the breed should always keep the type of domestic animal in an unstable state (maintain variability). It seems that this important factor of significant variability has always been noted among domesticated breeds.
Heinz thought it was a good idea to use popular sires because he thought they were quite different from each other and would not allow too much uniformity among the breed.
What is the connection between the popular breed who helped improve the quality of the gene pool in 1915 and the source of the problem breeders are trying to reach 100 years later?
What is this “syndrome” that geneticists are so concerned about today?
To understand the essence of the problem, it is necessary to understand the basics of genetics. You probably know about mutations – DNA particles that do not replicate perfectly or may have been damaged by some kind of environmental toxins.
If the mutation is dominant and affects some vital processes, then it is removed from the gene pool by natural selection, such an individual will not be able to pass on its genes to the next generation.
But many mutations do not have negative consequences, since they are paired with a dominant, normally functioning allele.
These “recessive” mutations do not manifest themselves into the genome and can be passed on to the next generation just like any other gene, and as long as the offspring has a copy of the normal allele, the mutation does not appear.
Mutations become a problem when an individual inherits two identical copies of an allele, i.e. is homozygous.
Without at least one normal, unmutated allele, of a gene cannot function properly, and the consequences can range from something relatively trivial (for example, different eye colors or slightly short legs) to catastrophic (for example, blindness, disruption of vital biochemical parameters, cancer).
Mutations happen all the time. Mutations, the adverse effects of which are immediately visible, are removed from the gene pool by natural selection, while recessive alleles remain in the genome as a “genetic load”. Every dog - in fact, every organism – has its own unique set of damaged alleles that do not harm as long as there is a copy of the normal allele that works as intended.
Negative effects of popular sire syndrome:
The popular sire effect (also called popular sire syndrome) is a major concern. In the best of cases, this syndrome can very quickly lead to depression in the canine population.
In the worst case, this can lead to the extinction of the dog population. This phenomenon occurs when the male is widely used for reproduction, rapidly spreading his genes throughout the gene pool.
Three problems arise from the producer effect:
- Any harmful genes carried by the father will increase significantly in frequency in the population, which can lead to new breed-related genetic disorders or deficient traits if the father is perceived to be exceptional but not genetically resistant.
- A limited number of females breed annually. Intensive use of a popular male in breeding conditions precludes the use of other males, reducing the diversity of the gene pool.
- If strong and productive brood lines in a colony are flooded by a brood or breeding line, any potential harbored in those lines may be lost in the future due to the negative effects of a brood’s genes.
Popular sire syndrome is not limited to breeds with small populations. Some of the more populous breeds have had problems with this syndrome. Also, there are several cases where a popular father is replaced by a son and then a grandson. This creates genetic bottlenecks in the tribal population, reducing the variety of available genera.
Another thing to consider, if you own a ‘popular sire’, is that if he is overused, the potential to ‘double up’ on his positive genes will also ‘double up’ on the negatives. The ‘inbreeding’ coefficient should remain under 15%, whenever possible! The lower this number is, the better. Any breed needs variety but they also need stability. As a breeder, think about these factors when choosing to mate your dogs. All mating should be for the betterment of the breed you are working with.
If you want to use a ‘popular sire’, consider what he has to offer your female. Just because a dog is ‘popular’ does not mean he is a good choice for YOUR female. Some lines do not bring out the best example of the breed, when mixed. Is the sire ‘popular’ just because of his looks? What is his temperament like? Will it match up to your female’s temperament? For instance, if the sire has a dominant, aggressive, or hard temperament and your female also has a one of these types of temperament, the puppies will likely have similar temperaments-or even worse. What is the breed ‘standard’ for your breed? Are they supposed to be well-balanced temperamental dogs? If so, you do not want to mate these two dogs together!
Another thing to consider is how old that ‘popular sire’ is. How old did his parents live to be? If they met or exceeded the ‘average age’ for your breed, than that is a positive. How about his littermates? Any health issues like cancer, heart disease, and dysplasia? These are all very important things to look at and consider, when breeding! I remember hearing a story about a ‘popular sire’. This dog was an AKC champion that won many awards before he was even 4 years of age. He was also said to have sired a minimum of 25 litters (definitely a popular sire). The problem was, he died before he turned 5 years old, from a ‘genetic’ form of cancer! Just think about all the litters he sired, the poor owners and breeders now had to be concerned about every dog he created! Not to mention what the possible negative effects would be on the gene pool of his breed. The dog’s owner did some health testing like heart, eyes, hips and elbows. However, they did not pay attention to the fact that his sire died at the age of 7 from cancer (average lifespan of this particular breed is 13-15yrs) and the breeder told him the cancer was not genetic! Unfortunately, he would find out this was false. This popular sire had created more than 100 dogs! Something to think long and hard on and a lesson for all breeders to do your research and never use a dog based solely on how popular he is or how many awards he has won. Concentrate on health and temperament, not just looks and awards!
One other thing to consider when picking a stud-is he proven? Whether he is a ‘popular sire’ or not, does he throw himself to his offspring? Not all males do. Then, of course, you have studs that are ‘decent’ but not superstars but—they create superstars, over and over again. They can become ‘popular sires’ because of what they throw, not because of them being one of the best in breed! The bottom line…do your research before picking a stud! Find out as much information about the studs history and genetics so you can breed responsibly.