Greyhound Genetics Question

[philospher77]

Hi!

 

I was reading an article recently about why breed registries and closed gene pools were really not a good idea (basically, when you close a gene pool, you keep concentrating the bad genes as well as the good ones, and since genes are lost with every generation (since not all the animals will reproduce), you wind up with less and less diversity.) But one of the reasons they offered for why it's also not a good idea is that it doesn't work. In other words, breeding the best examples of the breed together gets you more of the same, but it doesn't get you improvements in the breed. Greyhounds were cited as an example. So I am turning to you good people to see if you can answer the following questions, since they talked in generalities in the article.

 

The first greyhound track opened in 1912, according to wikipedia. So that's roughly 100 greyhound generations, assuming one per year. Does anyone know if the percentage of pups per litter that flunk out of training school is smaller now than it was in the past? And are greyhounds appreciably faster now than they were in the past? I speculate that there was an initial increase in speed as the breed was getting established and matings could be better documented and controlled, but that, according to the viewpoint in the article, the speed should have reached a plateau and been essentially unchanged since then. Same thing with the number of pups that actually have the potential to race. Of course, the alternative (the idea that you could get a faster dog if you allowed outcrossing) is harder to research, since those dogs are barred from racing and thus the data is not readily available.

 

This is mostly idle curiosity on my part, but it's been niggling at the back of my mind and I figured I would see if I could get an answer from knowledgable folk.

 

Thanks!

[JJNg]

The idea that closed registries are generally a bad idea is one that is based on population genetics, and is a principle that I agree with. Unfortunately, few dog breeders today seem to understand this concept, and closed gene pools have become the norm with the advent of breed registries and an apparent obsession with breed purity. Greyhounds existed for centuries without the need for breed registries and a closed gene pool - that didn't start until the late 1800s.

I'm not sure I agree with the premise that selective breeding within a closed gene pool "doesn't work". There is always a range of characteristics within a gene pools, and when you selectively breed individuals with specific traits, you will get a shift toward those traits in future generations. You tend to also get other unexpected changes due to genes linked to the genes that are being selected for. What was the author's explanation for why you don't get 'improvements' in the breed?

I'm not sure how feasible it is to compare the speed of greyhounds of the past to greyhounds today. Too much variation in track surface and conditions, timing methods, as well as possibly diet, nutrition, and physical conditioning to make a direct comparison. Human athletes do seem to be getting better, faster, stronger, etc as seen by world records being topped each year at the Olympics, but it's due to a lot of different factors, and likely has little to do with 'selective breeding'.

Looking at percentage of pups that flunk out of training school also won't tell you if the breed has 'improved' because a greyhound's speed and agility is always judged relative to other dogs. There isn't a fixed speed that greyhounds need to achieve to race. They just need to be faster than the majority of the competition to be successful. So even if the overall population of dogs is faster, you still have the same percentage of winners. (Not sure if I'm explaining this very well. LOL)

And actually, most greyhounds aren't bred until they are 4-5 years or older, so from 1912 to today, you're only looking at about 20 generations of greyhounds. You can see this by browsing pedigrees on Greyhound-Data.

 

When it comes to a breed that is already very specialized like the greyhound, outcrossing isn't necessarily going to result in any 'improvements'. Outcrossing to a slower breed isn't going to get you faster dogs, and there aren't any faster breeds than greyhounds. From the standpoint of genetic health, I do think it's important to keep genetic diversity in mind and maximize the use of the population, perhaps with careful outcrossing for health (but not necessarily performance) reasons.

Btw, if you're interested in reading more about population genetics and how it applies to purebred dog breeding, here's a good website:

Canine Diversity Project

Edited December 18, 2013 by JJNg

[DocsDoctor]

Good topic, thanks for raising it - I read JJNg's reply with interest and shall hope to learn more as the thread develops! I'm no expert but interested in the historic context and would point out that here in the British Isles there are three distinct types of greyhound - the courser, the racer, and the show dog - and that the split has emerged over the last hundred or so years.

 

1. The courser. Historically the purpose of a greyhound was to hunt, not race round a track! Rules for coursing (in which two greyhounds at a time compete in the pursuit of a hare) were codified by the sixteenth century, but it was from the late eighteenth century that competitive coursing, selective breeding and the keeping of stud books really took off, with the Waterloo Cup (the big prize) first awarded in 1836. Coursing has been illegal in the UK since 2005, but still goes on in Ireland, where the Irish Coursing Club still holds the stud book for racers and coursers alike - with some crossover between the two types, but coursers tend to be taller and bigger-boned than the racers, with deeper chests, heavier legs - they need the stamina to be able to run twice a day, over uneven terrain.

 

2. The racer. I believe that when racing became popular in England in the 1920s many Irish coursers were imported - they proved better at it than the English ones, because they had a background in 'park coursing' (coursing in an enclosed space, by then illegal in England) which favoured sprinting rather than staying power. As a new specialist racing dog emerged through selective breeding it tended, not surprisingly, to become shorter and slighter than the courser.

 

3. The show greyhound. Again a distinct type - bred again from coursing stock, but this time for elegance - tall, narrow, exaggeratedly deep chest, elongated nose - following on from the foundation of the Kennel Club (in 1873), and the Victorian passion for competitive dog shows. Greyhounds actually won several relatively early Crufts Best In Show in 1910, 1914 and 1928.

 

Edited to add: of course I know that you have show (AKC) greyhounds in the States too. And I haven't attempted to answer the original question either, just thought some of you might like thinking about the history behind it all, like me!

Edited December 18, 2013 by DocsDoctor

[oldrunners]

I hope lots of folks jump in here. This is very interesting!

[Guest june]

OK, this is not as technical as other posts but just my opinion. Just because a grey flunks out of training, or does not make it to the track, does not mean the dog is not as fastor even faster than dogs that make it. It simply means the dog wouldn't race for whatever reason. One dog I had never raced (I don't know why) but she was much faster than my other dog (they were about the same size weight and age which are more factors) who raced over 100x and then went on to have puppies who also raced. My point is there are too many variables to make blanket statements.

[Guest Giselle]

I love genetics and genomics. It is, in my opinion, one of the most frustratingly fast and paradoxically slow fields of science It's incredible.

 

JJNg already hit a lot of fantastic points. Just to add: If there is one thing that I wish everyone understood about genetics, it is that genetics is VERY complicated and that we are toying with an extremely complex and sophisticated system when we do things like artificial selection and line/inbreeding. I wish that everyone, especially breeders, could understand the magnitude of the forces with which they're playing and to be extremely cautious and judicious in their practices.

 

Whenever we talk about dogs, we are often trying to simplify breed traits down to just a few very subjective characteristics. While "speed" may appear to be an objective trait, JJNg and DocsDoctor have already noted how complicated the concept of "speed" can become. When you want the fastest dog, do you mean the one with the longest stride? The fastest rebound? The most fatigue-resistant muscles? The most tenacious? The one who tolerates more pain? The one who does best on "X" type of turf? Already, the concept of "speed" and "fast" becomes extremely complicated by all the other variables. If you've ever spent time around Thoroughbred horses, you'll know immediately that this concept is not simple and definitely even harder to select for. So, as you can probably start to appreciate, it's pretty straightforward to select for ONE trait when it is inherited in simple Mendelian fashion and when it has an obvious phenotype, but it's MUCH MUCH harder (read: impossible) to select for a handful of interactive traits that are not inherited in simple Mendelian fashion and which may be heavily modulated by environmental factors.

 

Most traits that we desire in dogs, like intelligence or creativity or courageousness or speed, are a product of an enormous array of genes that interact with each other and with the environment. We humans do not understand genetics enough to be able to "engineer" these traits, much less breed for them. We can't. It's way too complicated. Aside from the complexity of the genome itself, we have to contend with issues like "epigenetics", or non-genic changes to how genes are expressed. For example, your dog may have inherited the gene for a black coat from his mom and a white coat from his dad (hypothetically speaking, let's say coat colors are inherited in a simple Mendelian fashion), you may expect the dog to be black because black is typically a dominant phenotype. BUT we have epigenetic changes, like DNA imprinting and methylation, that tamp down the black coat gene expression and actually allow your dog to look white, or maybe even black+white. This isn't the coat color you'd expect based on genes alone, but genes interact with each other, with epigenetics, and with the environment to create the creature we know as our dogs. It's foolish to think we can selectively breed for a singular trait and actually be successful. Perhaps this was what was meant by "failure".

[Guest Giselle]

I also want to add: Once you lose genetic diversity though inbreeding/linebreeding, it takes thousands - millions of years before that diversity can ever be regenerated. It is a complex, sophisticated system, and I personally don't think we should be toying with it without a solid appreciation for genetics. So, yes, I agree that closing those studbooks and closing off the gene pool is a detrimental action. But some breed clubs have been interested in or actually have reopened their books to infuse the breed with outside individuals. It's not like our dogs are doomed. We have choices. We can make educated decisions for the long-term betterment of our breeds.

 

And even if you outcross your super fast inbred Greyhound with a slower-but-genetically-diverse Greyhound, you could be infusing the next generation with a better mix of genes to ensure better health, maybe even better musculature/mental capacity/etc. Maybe the first generation of pups won't be as fast as the parents, but maybe the next generation of puppies have an overall physical advantage now. We don't know how it will work, but we know that diversity is the key and I think outcrosses are important for the long-term picture.

[greysmom]

Great discussion!

 

To put some numbers to it, I believe I read somewhere that about 60-65,000 racing (NGA registered) greyhounds are born in the US each year. Obviously this doesn't include backyard breeders, illegal racing breeders, coyote dogs, or AKC (though AKC registries are very low comparitively - maybe only several hundred a year).

 

Also, though one country's stud book may be closed, it is quite possible for breeders to import dogs from other countries with appropriate registry reciprocation. It's much easier now to get dogs from Ireland or Australia to add to a line. So genetic diversity can be increased in that way.

 

You also need to take technology advances into account. With the advent of artificial insemination and frozen semen, breeding from a single stud (even one long dead) becomes possible. There are studs on GD that have tens of thousands of descendants. This practice doesn't increase genetic diversity.

[philospher77]

The reason that the article mentioned the schooling failures was to demonstrate the complexity of genetics. Here we have a breed that is meant to do one thing: chase a lure very fast. Chasing the lure is a very basic thing, tied to prey drive, without which a dog in the wild would starve and die. So it should, technically, be easy to increase the number of dogs showing that drive with selective breeding. And yet, the article said that something like 25-30% of greyhounds just don't have it, even after generations of selective breeding. Which was given as an example of how selective breeding had "failed" to improve that desired trait in the breed. (Something like a retriever's soft mouth would be harder to breed for, since that goes against a dog's survival instinct.)

 

JJnG… while I agree that most greys aren't bred until 4-5, surely that only drops the number of generations down to 95? It's not like they go four years with no pups… the ones born in year one breed when they are 5, the ones born year 2 breed when they are 5, etc. Or am I incorrect?

[Hubcitypam]

Greys Mom - Just over 10,000 NGA greys are born in the U.S. each year.

 

The gene pool on the sire side is pretty narrow. As far as "flunking out of racing school" as in never reaching the track that can happen for lots of reasons that have nothing to do with speed. As one example some breeders have help back bitches with excellent bloodlines from the track to be broodies.

 

The dispute over closing the AKC stud books to NGA dogs has been going on for years. AKC greyhounds are a REALLY insular group. I think my friend Elaine may be one of the few people to cross register an NGA dog with the AKC and have a track dog that was a ring champion...time to trot out Abbey Lou...

http://www.greyhound-data.com/d?z=nDMe06&d=abbey+lou&sex=&color=&birthyear=&birthland=

 

Of course no greyhound genetic discussion would be complete with out Cee Jay. Then that dam's very next heat they bred her with another litter brother - what were they thinking????

http://www.greyhound-data.com/d?i=39795

http://www.greyhound-data.com/d?d=gts+kicker&x=40&y=17

Edited December 18, 2013 by Hubcitypam

[Guest Giselle]

The reason that the article mentioned the schooling failures was to demonstrate the complexity of genetics. Here we have a breed that is meant to do one thing: chase a lure very fast. Chasing the lure is a very basic thing, tied to prey drive, without which a dog in the wild would starve and die. So it should, technically, be easy to increase the number of dogs showing that drive with selective breeding. And yet, the article said that something like 25-30% of greyhounds just don't have it, even after generations of selective breeding. Which was given as an example of how selective breeding had "failed" to improve that desired trait in the breed. (Something like a retriever's soft mouth would be harder to breed for, since that goes against a dog's survival instinct.)

 

JJnG… while I agree that most greys aren't bred until 4-5, surely that only drops the number of generations down to 95? It's not like they go four years with no pups… the ones born in year one breed when they are 5, the ones born year 2 breed when they are 5, etc. Or am I incorrect?

I guess it makes more sense to say that each individual dog probably only has 20 generations, even though dogs are born each year. In terms of generations, though, I think 20ish is the right answer. Example: 2 generations separate myself from my grandmother. However, within that 40ish-year time span, there have been babies born each year - but those don't constitute any part of MY family history.

 

And, yes, genetics is complicated. If that was the moral of the article, then, yes That's pretty much it. It's complicated. Human-directed selective breeding is like throwing darts in the dark and hoping it'll land on a teeny tiny little bullseye... around the corner... behind a Plexiglass wall. It's impossible.

[DocsDoctor]

I guess it makes more sense to say that each individual dog probably only has 20 generations, even though dogs are born each year. In terms of generations, though, I think 20ish is the right answer. Example: 2 generations separate myself from my grandmother. However, within that 40ish-year time span, there have been babies born each year - but those don't constitute any part of MY family history.

 

Yes, absolutely. A generation = the average length of time from the birth of a parent, to the birth of a child. Usually calculated at about 25-30 years for humans, at least in the modern western world. See e.g. http://www.ancestry.co.uk/cs/Satellite?childpagename=UKLearningCenter%2FLearning_C%2FPageDefault&pagename=LearningWrapper&cid=1265124426382

[philospher77]

I guess it makes more sense to say that each individual dog probably only has 20 generations, even though dogs are born each year. In terms of generations, though, I think 20ish is the right answer. Example: 2 generations separate myself from my grandmother. However, within that 40ish-year time span, there have been babies born each year - but those don't constitute any part of MY family history.

 

 

 

 

That does make more sense, now that I think about it. Thanks!

[Guest Giselle]

Feel free to ask more questions. I'm slowly getting more time on my hands, and I love to talk genetics and genomics... even if I know just barely enough to eke by It's a very "hip" field these days!