The easy way to learn genetics
Trying to understand inheritance can be very difficult because most of the reading matter available is written by experts on the subject and they think that what is easy for them is also easy for the rest of us. It is not. Therefore, I will try and explain in simple language how it works. I have centred on Rough Collies as this is the breed I have but it is applicable to all dog breeds.
Before I go any further, I have to explain what a gene is and does. Genes are the building blocks of the dog. They control everything that makes up the dog from coat colour to teeth to heads. They are found in Chromosomes and there could be very many in each Chromosome. They are the DNA of the dog and there are at least 30,000 genes in a single dog. This is why every puppy is different. The problem we have in breeding dogs is that these genes keep changing for each generation. We can never tell exactly what we are going to get from a mating.
When a mating takes place the dog and bitch involved each give half of their genes to the puppies in the litter. In other words, each of the parents give the puppies 15,000 genes. Now the tricky part is that those 15,000 are not necessarily all the same for each puppy. They can be very different which is why every puppy in a litter is very different from its litter mates. Most of the genes are actually the same from each parent that is why a Rough Collie dog mates to a Rough Collie bitch will always produce Rough Collie Puppies. But some of the genes are different which makes the puppies different. Some genes will produce a light eye while others will produce a dark eye.
If your bitch has a light eye and you want to improve the colour so that the puppies will have a dark eye you have to use a dog with a dark eye. But it does not always work out the way you want. In theory if you have used a dog with a dark eye and there are 8 puppies in the litter with four dog puppies and four bitch puppies in the law of averages half of this litter will have dark eyes inherited from the sire while the other half will have light eyes inherited from the dam. However, things do not work out quite like that and more than likely you will find just one puppy with dark eyes, and he is the ugly dog in the litter. So, you start again.
Now it gets tricky, and this is one of the great joys of trying to breed better Rough Collies because you have to study the pedigree of your bitch and try to find out why she has a light eye. You will have to look at her parents to see if the fault lies with one or both. If they are clear of this fault you need to look at her grandparents. We have to understand that both her parents have contributed half their genes to her. Now we have to work out that her grandparents have contributed half of their genes to their offspring. The sire’s father has contributed half of his genes to the sire of your bitch. This equals to one quarter of the sires’ genes will have come from his paternal grandfathers’ genes and a quarter of his genes will have come from his paternal granddam. Following this line his maternal grandfather will have given him one quarter and his maternal grandmother will have given one quarter.
This means that the sire gives his offspring half (50%) of his genes. But it does not mean that he gives the same 15,000 genes to every puppy. His genes will be mixed up with his own sires genes and his dams genes. He in turn has received half of his genes from his sire and half from his dam. Working this out we can see that his sire has contributed a quarter of his genes to the new puppies as there
are four grandparents each contributing half of their genes to the next generation. The genes from the grandparents will be the same each time because they have already been given. This is all rather complicated and makes breeding dogs rather difficult because it is mainly hit and miss. It now follows that each generation back will give half of their genes to the next generation so that the great grandparents will have given one eight of their genes to the puppies.
First you need to understand pedigrees. I will do a very simple pedigree that is classed as an outcross mating as all the names of the Collies are different.
Pedigree of Lassie a bitch with light eyes – This is an outcross mating
| Bob sire of Lassie (50% genes to Lassie) | Bill Sire of Bob (25% genes to Lassie) | Dick sire of Bill (12.5% genes to Lassie) |
| Jill dam of Bill (12.5% genes to Lassie) | ||
| Sue dam of Bob (25% genes to Lassie) | Joe sire of Sue (12.5% genes to Lassie) | |
| Pat dam of Sue (12.5% genes to Lassie | ||
| Nan dam of Lassie (50% Genes to Lassie) | Jack sire of Nan (25% genes to Lassie) | Tom sire of Jack (12.5% genes to Lassie) |
| Aggy dam of Jack (12.5% genes to Lassie) | ||
| Nell dam of Nan (25% genes to Lassie) | Ken sire of Nell (12.5% genes to Lassie) | |
| Joan dam of Nell (12.5% genes to Lassie) |
If you are seriously interested in breeding better Collies and are serious about wanting to improve the eye colour for the next litter it is in your interest to track down the parents, four grandparents and eight great grandparents of your bitch to find out which one is light in the eye. With this breed which is numerically quite large you should not have to look any further back than these three generations.
Once you have found the culprit and it will be on either her sire’s side or her dam’s side or both sides. You will need to find a dark eyed dog that does not have any of the affected dogs or bitches in his pedigree and he has been proved to produce mostly dark eyed puppies. Also, it is most important that the sire you use is strongly line bred. I will explain that term later.
The genes from parent to offspring are always the same but as there are so many genes in each package, they can vary the outcome dramatically.
In dog breeding we need to have a little of what we call line breeding. In other words, a dog or bitch appears twice in a pedigree so that if we change Nell to Sue. Sue is now the grandmother to the puppy on both sides as follows.
Pedigree of Lassie with light eyes – This is a linebreeding mating
| Bob sire of Lassie (50% genes to Lassie) | Bill Sire of Bob (25% genes to Lassie) | Dick sire of Bill (12.5% genes to Lassie) |
| Jill dam of Bill (12.5% genes to Lassie) | ||
| Sue dam of Bob (50% genes to Lassie) | Joe sire of Sue (25% genes to Lassie) | |
| Pat dam of Sue (25% genes to Lassie) | ||
| Nan dam of Lassie (50% Genes to Lassie) | Jack sire of Nan (25% genes to Lassie) | Tom sire of Jack (12.5% genes to Lassie) |
| Aggy dam of Jack (12.5% genes to Lassie) | ||
| Sue dam of Nan (50% genes to Lassie) | Joe sire of Sue (25% genes to Lassie) | |
| Pat dam of Sue (25% genes to Lassie) |
This is an example of a line bred pedigree. One or more dogs appear twice or more in the pedigree. But none are too close to Lassie. We see that Sue has given 25% of her genes to the Lassie on both sides of the pedigree. Therefor her contribution has gone up to a total of 50%. But the genes will be very different for each batch because she will give a different 15,000 genes each time. It follows that her parents have doubled their contribution as they are also on this pedigree twice. The Kennel Club does not like this type of breeding, but you have to do it to keep a type and it helps to eliminate faults that are prevalent in your breed. I remember speaking to a breeder from another breed who had been told by the Kennel Club to outcross as his breeding was getting too close. This became a total disaster because he got faults that had never been in his line. It is always a risk when you outcross as you do not know what you are bringing into your line.
Next is an example of inbreeding. This is when a brother and sister are mated together. Or maybe father and daughter mating. It should not be done too often because some really bad genes could be encouraged but you need to do it to consolidate a type.
Pedigree of Lassie This is an inbreeding mating because Bob and Nan are brother and sister.
| Bob sire of Lassie (50% genes to Lassie) | Bill Sire of Bob (50% genes to Lassie) | Dick sire of Bill (25% genes to Lassie) |
| Jill dam of Bill (25% genes to Lassie) | ||
| Sue dam of Bob (50% genes to Lassie) | Joe sire of Sue (25% genes to Lassie) | |
| Pat dam of Sue (25% genes to Lassie) | ||
| Nan dam of Lassie (50% Genes to Lassie) | Bill sire of Nan (50% genes to Lassie) | Dick sire of Jack (25% genes to Lassie) |
| Jill dam of Jack (25% genes to Lassie) | ||
| Sue dam of Nan (50% genes to Lassie) | Joe sire of Sue (25% genes to Lassie) | |
| Pat dam of Sue (25% genes to Lassie) |
In this case Bob and Nan will in theory give one hundred percent of their genes to Lassie as they each give her fifty percent, which being brother and sister should be the same. However, theory does not work in this case because the two lots of fifty percent from Bob and Nan could be very different. After all there are 15,000 genes that they are both giving. Obviously, some of the genes will be the same but we do not know how many. It is all guesswork. I think that an outcross mating is much more dangerous than the occasional inbreeding. Outcrossing we do not know what we are going to get. It is all just plain luck. In Rough Collies the mating between Dazzler of Dunsinane and Ch Witchcraft of Rokeby was in hindsight a fantastic outcross mating as it was so successful. It was pure luck that it turned out so well. It could have gone horribly wrong with Dazzler being a nervous wreck. The puppies from this litter were actually very sound in temperament.
To try and eliminate the light eye we must study the first pedigree to find out which of these Collies has a light eye. It will almost certainly be one of the bitches in the pedigree because we have to assume that no breeder is going to mate their bitch to a light eyed dog. We have to accept that a dog with a light eye is not going to be used at stud. Nor is he going to be shown as this is a rather easy fault for judges to see. But we get what we call rogue Genes (the experts have another name, but we won’t go into that here). In other words, a gene can jump a generation or even more so that we can get strange things happening out of the blue. A gene can come from as far back as ten generations to rear its ugly head and cause some grief. We call this Mother Nature, and no scientist has ever been able to cure or control Mother Nature.
One instance is in my own kennel. I have a young bitch that has a very big soft wavy coat. I have looked at a very extended pedigree of her and cannot find another instance of this fault. I suspect a dog in the ninth generation that had this type of coat. It was much admired in those days but is rather frowned on now. I have always disliked that type of coat so made sure that I steered well away from any dog that might cause me some trouble. It still came back to cause trouble. This is dog breeding, and it is not for the faint hearted.
Back to eyes. Looking at as many of the dogs in the outcross pedigree we see that Pat has light eyes. Therefore, we have to make sure that the dog we use on Lassie does not have any of Pat’s breeding in at least the first five generations.
Pat has light eyes, but her daughter Sue has a dark eye and so does her daughter Nan. Therefore, the gene that has caused the light eye has jumped three generations and is very virulent as it caused most of the puppies in Lassie’s first litter to have light eyes. To overcome this problem, we need to find a dog with a very strong line of dark eyes.
Having now used the chosen dog and he has been successful in that most of the puppies in Lassie’s second litter have dark eyes, we now have to consider the sire to use on the bitch puppy we have kept from this mating. I would strongly suggest that you use a dog from the same line as the dog you used successfully. And a strong linebred dog as it will help you to produce your own line for the future.
Whilst on this subject do not be afraid of line breeding. Most wild animals are in bred and we started our very successful kennel by inbreeding. Unfortunately, the Kennel Club will not allow inbred puppies to be registered but they will accept line bred puppies. It really is time that The Kennel Club realised that inbreeding is good.
This is an example of inbreeding that worked out so well for us.
Pedigree of Corydon King Hector
| Royal Flush of Rokeby Full brother to Ch Royal Ace and Ch Romney of Rokeby | Dazzler of Dunsinane | Dorgano Demander of Dunsinane |
| Leecroft Leading Lady | ||
| Ch Witchcraft of Rokeby | Prospecthill Rustler of Rokeby | |
| Retta of Rokeby | ||
| Corydon Regality of Rokeby Brother sister mating | Ch Royal Ace of Rokeby | Dazzler of Dunsinane |
| Ch Witchcraft of Rokeby | ||
| Ch Romney of Rokeby | Dazzler of Dunsinane | |
| Ch Witchcraft of Rokeby |
For me inbreeding is a very valuable tool when breeding dogs. The above proves my point. Maybe it worked out so well because of the outcross mating of Dazzler and Witchcraft mating. We will never know on this one, but we did not get any nasty genes as Hector was a big very sound well coated dog with a very calm temperament. He did not inherit any of the gross nervousness of Dazzler of Dunsinane. I suspect that Ch Witchcraft of Rokeby had the stronger genes as she was a big strong bitch.
The mating of Dazzler of Dunsinane and Ch Witchcraft of Rokeby was an example of a very outcrossed pedigree. It was not until the sixth generation that a dog appeared on both sides of the pedigree. This was very strange as the Rough Collie has quite a small gene pool. We can trace our male line to just one dog albeit he was born in 1878.
We used Corydon King Hector on an outcross bitch from our previous line. This bitch was Ch Corydon Qui Vive. She was by a Ch Larkena Vanara Golden Victor son and her dam was Corydon Regality of Rokeby. We kept in the Rokeby line but did an outcross. This mating produce one of our very best bitches, our first UK Champion and for me one of the best looking bitches I have ever seen. This was Ch Corydon Hippolyta. She was the dam of four champions to three different sires. They were Ch Corydon Polymerus at Bririch and SA Ch Corydon Polyphemus at Bririch both by Ch Bririch Gold Edition. Ch Corydon Polyhera by Ch Corydon Handsome Hero and SA Ch Corydon Polly Wagtail by Sandiacre Softly Softly. She was also the dam of two of our most productive dams in Corydon Pollytucka and Corydon Polyhanna, both were the dams of two Champions.
Pedigree of Ch Corydon Hippolyta
| Corydon King Hector | Royal Flush of Rokeby | Dazzler of Dunsinane |
| Ch Witchcraft of Rokeby | ||
| Corydon Regality of Rokeby | Ch Royal Ace of Rokeby | |
| Ch Romney of Rokeby | ||
| Ch Corydon Qui Vive | Corydon Quo Vadis | Ch Larkena Vanara Golden Victor |
| Corydon Coalblack Maid | ||
| Corydon Regality of Rokeby | Ch Royal Ace of Rokeby | |
| Ch Romney of Rokeby |
This is almost inbreeding, but we do have an outcross line in Corydon Quo Vadis. I have to say that we have never bred as closely as this since this mating. The kennel Club will not allow us to do this mating at the present time.
Before I finish, forget COi figures as they are meaningless unless you are a real expert
Copyright John Blake (Corydon)
Corydon Collies 