What's the difference between a "breed" and a "hybrid" in chicken taxonomy?

[toucan]

The biological taxonomy of the common chicken is Gallus gallus domesticus. In other words, this would mean that any "breed" of chicken, whether it's a leghorn or a silkie or whatever, is exactly the same genus, species and subspecies as any other. So, a "breed" of chicken, then, is nothing more than a group of Gallus gallus domesticus that displays a certain homogenous physical appearance and has a set of homogenous characteristics that go along with that homogenous appearance. Supposedly, all common chickens descended from and are a subspecies of the red junglefowl (Gallus gallus) and the different "breeds" have been achieved over the last 6000 or 8000 years of domestication through selective breeding to single out specific physical and/or behavioral characteristics, much in the same way as all of the different breeds of dogs make up a single subspecies (Canis lupus familiaris) of their common ancestor, Canis lupus.

OK....so what then is a "hybrid" chicken? I have seen some websites claim that a "hybrid" chicken is nothing more than a cross between two "breeds"? But two different "breeds" of chickens still belong to the very same subspecies. And a hybrid, at least from a biological taxonomy perspective, is an offspring resulting from the cross between two different species of animals. Now maybe lay chicken taxonomy is different than biological taxonomy and these websites are correct, and I'm OK with that.....but, the way we continue to make more "breeds" is by crossing existing "breeds", so why would we ever refer to any crosses at all as hybrids? With this type of taxonomical system, how would one ever truly distinguish a "breed" from a "hybrid" in the chicken world? I would expect that the results of any cross between two different "breeds" which didn't exhibit any obvious common set of homogenous characteristics would simply be referred to as a "mixed breed" or something equivalent to the "mutt" in the dog breeder's world.

The reason I'm curious about this is because I have read that some chicken "breeds" have better fertility rates than others. Inbreeding can surely explain this, but if the same good husbandry standards and practices have been used for the development of all "breeds" to keep inbreeding to a minimum, one would think that all "breeds" would have about the same fertility rate (unless, of course, infertility is simply a homogenous genetic characteristic that runs parallel to certain homogenous physical appearance characteristics, and this is certainly possible). But, assuming the former to be true, then true hybridization (the crossing of two similar but different species) present in the history of some "breeds" could account for infertility rates to be different between different "breeds".

To confuse matters worse, some people believe that Gallus gallus domesticus, the common chicken, is an ancient hybrid cross between red junglefowl (Gallus gallus) and gray junglefowl (Gallus sonneratii). This would mean that all common chickens, regardless of "breed", would be true hybrids. But, whether or not there was hybridization between G. gallus and G. sonneratii early on in the development of Gallus gallus domesticus, is it possible that the development of more recent "breeds" (say, within the last 1000 years) are the result of some hybridization between Gallus gallus domesticus and another species within the genus Gallus? If so, this would mean that some "breeds" are not Gallus gallus domesticus and some are.

Any thoughts on any of this? This is a subject that, as an unschooled backyard biologist/zoologist (I'm a degreed technologist with a passion for natural sciences), is of great interest to me.

 

[3riverschick]

OK....so what then is a "hybrid" chicken?
==================
Forget Carl Linnaeus for a moment. He is not necessary to answer your question. Neither is it expedient to extrapolate back to the beginnings of Gallus Gallus. You need go no further back than the beginning of the purebred animal craze in England during the Victorian era.
During this time the concepts of pure-breeding breeds and varieties came into popular acceptance. The concept of an individual strain of one's own making within a breed or variety became the goal of middle class animal breeders. The need for animals which were more individually productive to meet increasing needs for quality food. The rise of modern food preservation which required large amounts of a single animal product like chicken, beef, pork, etc. The "hybridists" of the middle of this century ( 1800-1900) had already been published and drawn attention to their work. So.. long story short, animal breeders discovered if they mixed 2 or more breeds, the offspring often manifested increased vigor and the positive sides of both the sire and dam lines. More money for them.
Full Definition of HYBRID per Webster: 1 an offspring of two animals or plants of different races, breeds, varieties, species, or genera

In the case of poultry it is generally considered breed (or variety within a
breed). Consider here we are discussing "pure-breeding" breeds. Breeds
which self-replicate when male is mated to female. "Like produces like".
Go no further than that and leave Linnaeus out of it . One can have several
kinds of hybrids.
Double hybrid: cross between two different breeds or varieties. Usually to
enhance egg or meat or hybrid vigor qualities. The most used cross by
non-commercial poultry breeders.
Triple hybrid: for market or to found a strain. The third cross is the terminal
cross (A+B+C) and sent to market. (beef)
In poultry, the veteran breeders expound not to strain-cross to found a flock
within a breed but to find a quality vintage strain and line breed it for
improvement. There is a Darwinian Law of Variation which is helpful in finding
success in founding a strain on 3 strains. One does not see triple hybrids
used much in poultry because genetic variation is exponential, not arithmetic.
The plethora of sex-linked genes makes any kind of hybridizing in poultry a
real challenge.
Quadruple Hybrid: A scientific crossing of 4 breeds of poultry to
create super layers. Used by commercial egg industry.
Hybridizing to found a breed : Done by poultry experts with 10-20 years
to finish the project.
Best Regards,
Karen
Waterford english Light Sussex
PA, USA

 

[Ridgerunner]

I’m an engineer, not a biologist, but I’ll give my perspective. My opinion may have some flaws in it and I’m certain some people will disagree, but maybe it will at least contribute to the conversation.

All breeds are man-made. Someone (or a group) decides what they want in a chicken breed and then develops it through selective breeding. To me, this article on how the Ameraucana was developed from EE’s is fascinating and illustrates the point.

Ameraucana History
http://www.ameraucana.org/history.html

Breeds were originally developed for a specific purpose. Silkies and Polish for decoration, Delaware and New Hampshire for meat, Leghorn for eggs, and Rocks or Wyandotte for dual purpose, for example.

Let’s discuss Delaware or New Hampshire. They were developed as a meat bird before the Cornish X came about. Some things were important; skin color and feather color to give a nice carcass, body confirmation and size to get the cuts of meat, their feed to weight conversion, since they were raised in pens, take confinement well. Things like that. Since they were a meat bird, how important were things like eye or egg shell color or number of points on the comb, especially if they were marketed without a head? A few years ago, someone had a copy of an advertisement for a Delaware as a meat bird. The selling point was that the chicks could reach 4 pounds at 10 weeks, not crispness of barring.

But when people decided they wanted to show their birds against each other, they needed rules so they wrote the breed description. That related to the utilitarian uses of the bird if they had one, but also other things just so they could judge one chicken against another. They’d decide on a birds head shape and body confirmation and decide a specific type comb would look best on that breed. Things like that.

Something to maybe consider. Why are there so many different recognized colors and patterns of Ameraucana, Rock’s, Wyandotte’s and all that? It’s so people can show against each other. What are the different utilitarian purposes of a Barred, Partridge, White, or Buff Rock?

One thing that complicates it for me is that many people raise birds for show. The traits they are breeding for are the traits a judge will see. A judge won’t see the color of egg the hen lays, how efficiently they convert feed to eggs or meat, or a lot of flock behaviors. For example, Rhode Island Red roosters have a reputation on this forum of being human aggressive. Originally they were not. RIR’s were a backyard flock used for eggs and meat. A lot of the time, kids gathered eggs and fed and watered them. If a rooster attacked a kid, it wound up on the dining room table as guest of honor. The true heritage RIR’s were not human aggressive. But if a hatchery or a breeder does not cull the human aggressive roosters, you can wind up with RIR’s that are often human aggressive. There are a few people that are trying to raise Barred Rock or RIR or such that consider the behavioral traits of the birds as important as what the judge sees. But those people are pretty rare.

There is no DNA testing that I’m aware of that can tell a Barred Rock from a RIR from a mutt barnyard mix. All breeds were developed by selective breeding, usually by crossing certain breeds but sometimes taking advantage of a mutation. If someone really knew what they were doing and had patience, they could cross RIR’s with Buff Rocks and in a few generations have a bird they could show as a New Hampshire. Breeds are something made by man, whether that is in chickens, cattle, or horses.

It’s not that unusual for people breeding for show to bring in an outside breed to introduce or eliminate a certain trait. They then have to go through a rigorous exercise over several generations to breed out the traits they don’t want and keep the ones they do. A purebred chickens is one that will pass on certain traits consistently. Because of all the recessives that you can introduce by crossing in an outside breed, they have to go a certain number of generations to be able to call their flock “purebred”.

Anyway, that’s my opinion. I think everyone has one of those.

 

[toucan]

OK....so what then is a "hybrid" chicken?
==================
Forget Carl Linnaeus for a moment.

What? Forget Linnaeus? Ah, OK, what the hell. He was just lucky that binomial nomenclature ended up working out with plant and animal taxonomy even after Darwin figured out evolution.

Anyway, Karen, great post. Thanks for replying.

So, chicken taxonomy doesn't conform to the same rules as biological taxonomy, and that's actually what I had suspected. So, a "hybrid" in the chicken world is simply a cross of two or more "breeds" or "varieties", then. And, so, it's not surprising that offspring of two or more breeds will exhibit more vigor. There's a certain amount of inbreeding that goes into the development of any breed, I'm sure. And, the continued propagation of any breed will continue to suffer some consequences of continual breeding within a limited number of familial lines. So, any cross between breeds will surely break open that genetic bottleneck and the result will be a more vigorous bird. And, we will call that bird a hybrid!

Now, as far as distinguishing between a chicken "breed" and a chicken "hybrid", let's see if I have it straight. A "hybrid" is any cross between two or more existing breeds. A "breed" is the product of crossing two or more existing breeds and their offspring for some number of generations in order to produce a chicken with a distinct set of genetic characteristics or traits that will, when a rooster and hen with this same exact set of traits mate, produce predictable offspring that will have the same exact set of genetic traits as both parents. Does that sound right? And what governing body of chickendom decides which set of reproducible genetic traits constitutes an official "breed"? I've heard of the existence of some distinct "varieties" that have not been recognized as breeds by the "authorities". Is this just because nobody has yet taken the time to look at these varieties or is it because they aren't different enough than some other existing variety or what?

Now, let's bring Linnaeus and Darwin back into it for just a minute because I'm fascinated with the Gallus genus at the moment. Do you think modern day chickens, with all their diversity, are just a product of 8000 years of domestication and selective breeding of Gallus gallus or do you think there was some biological hybridization going on with another species or two of Gallus early on? And, do you think that level of hybridization (the introduction of bloodlines from a completely different species of Gallus) has occurred in more recent times to create any of the breeds we know and love today?

The grey junglefowl is pretty rockin':
http://upload.wikimedia.org/wikipedia/commons/b/b6/Gallus_sonneratii_(Bandipur).jpg

The green junglefowl is interesting:
http://upload.wikimedia.org/wikipedia/commons/1/1b/Stavenn_Gallus_varius_0.jpg

And check out the Sri Lanka junglefowl:
http://upload.wikimedia.org/wikiped...Ceylon_Junglefowl_(Gallus_lafayetii)_Male.jpg

 

[toucan]

I’m an engineer, not a biologist...

All breeds are man-made.

It’s not that unusual for people breeding for show to bring in an outside breed to introduce or eliminate a certain trait. They then have to go through a rigorous exercise over several generations to breed out the traits they don’t want and keep the ones they do. A purebred chickens is one that will pass on certain traits consistently. Because of all the recessives that you can introduce by crossing in an outside breed, they have to go a certain number of generations to be able to call their flock “purebred”.

Hey RR

I'm an engineer too...software development. What kind of work do you do?

Anyway, I think your post was right on. And, yes, I think we all agree that all breeds are man-made because they take some number of generations of very selective breeding to produce.

Interesting that people can introduce a totally different breed into a line of a breed to change one or two characteristics of the bird and after some number of generations they can breed out everything about that introduced breed except for the favorable qualities and get back the exact physical characteristics of the original breed.

Thanks for the link on the Ameraucana. The araucana is an interesting bird. Imagine a descendent of Gallus gallus already being here when the first Europeans "discovered" the new world! I have read somewhere that there are two schools of thought on this, one being that the first people that crossed the Behring Straits from Mongolia into modern day Alaska during the last ice age, and subsequently populated the Americas, either brought chickens with them or they kept some line of transportation and trade open after they were here and the chicken finally made it that way. The other school of thought was that the chicken had been introduced to the indigenous people in South America by pre-Colombian visitors from places like Polynesia. I happen to think the first explanation is probably more likely and it would mean that Gallus gallus was being domesticated as far back as 15,000 to 20,000 years ago, I suppose.

 

[Ridgerunner]

Toucan, does Costa Rica have its own set of chicken standards. What is considered a breed varies from country to country. An easy example, in France, a Marans has feathered legs. That’s not necessary in the US of A. The differences in breeds is purely man-made.

I don’t have the expertise to answer your question about hybridization. Genetic testing could probably answer that.

 

[toucan]

Good question about the recognition of breeds in Costa Rica. I don't really know, but I suspect that there is no governing body for registered chicken breeds here. I have never seen a poultry exhibition and while I have met several breeders here, I really have to question the "pure-bredness" of their "razas" after inspection. Most chicken keepers here are rural people interested in the production of eggs and/or meat and the most important thing to them is acquiring chickens that require the least bit of care and maintenance to survive, produce eggs or meat, and reproduce. The hatcheries here produce an egg layer that is probably an auto-sexing cross of a RIR. They also produce a meat bird that is white and grows very fast. There are also the remnants of other breeds (probably brought in from the US via Panama) scattered throughout the country and they get mixed into peoples' flocks. The bare-necked breed is commonly seen here, as are barred Plymouth rocks and some other breeds, but they have mostly assimilated into mixed flocks and purebreds, if there are any outside of the two breeds produced by the hatcheries, are rare.

Once in a while, someone with an importation permit brings in a shipment of birds from a US hatchery. I'm in the process of getting those permits so I can import the birds of my choice. Right now I'm having fun with the barred Plymouth rocks that I can get down here from local chicken enthusiasts who do their best to produce pure ones. They are amazingly bulletproof here in the tropics.

 

[3riverschick]

What? Forget Linnaeus? Ah, OK, what the hell. He was just lucky that binomial nomenclature ended up working out with plant and animal taxonomy even after Darwin figured out evolution.

Anyway, Karen, great post. Thanks for replying.

So, chicken taxonomy doesn't conform to the same rules as biological taxonomy, and that's actually what I had suspected. So, a "hybrid" in the chicken world is simply a cross of two or more "breeds" or "varieties", then. And, so, it's not surprising that offspring of two or more breeds will exhibit more vigor. There's a certain amount of inbreeding that goes into the development of any breed, I'm sure. And, the continued propagation of any breed will continue to suffer some consequences of continual breeding within a limited number of familial lines. So, any cross between breeds will surely break open that genetic bottleneck and the result will be a more vigorous bird. And, we will call that bird a hybrid! Correct.

Now, as far as distinguishing between a chicken "breed" and a chicken "hybrid", let's see if I have it straight. A "hybrid" is any cross between two or more existing breeds. A "breed" is the product of crossing two or more existing breeds and their offspring for some number of generations in order to produce a chicken with a distinct set of genetic characteristics or traits that will, when a rooster and hen with this same exact set of traits mate, produce predictable offspring that will have the same exact set of genetic traits as both parents. Does that sound right? Yes.

And what governing body of chickendom decides which set of reproducible genetic traits constitutes an official "breed"? The national poultry association for that country for that size of poultry. In USA, The APA (large fowl) and the ABA ( Bantams)

I've heard of the existence of some distinct "varieties" that have not been recognized as breeds by the "authorities". Is this just because nobody has yet taken the time to look at these varieties or is it because they aren't different enough than some other existing variety or what?
Could be both. In poultry associations there is usually a set procedure for getting a breed "recognized. That is, approved as a pure-breeding breed with a certain set of characteristics. In the US it requires a certain number of breeders breeding the breed for a certain number of years. A qualifying "meet" ( show) where birds of the unrecognized breed are shown and a passing ratio of them adjudged "worthy" of the breed's Standard which has previously been written by the national parent club of that breed, (and approved by the APA). There are more details on this, but those are the basics. So it involves a coordinated effort by many people over time to get a breed recognized.
t
Now, let's bring Linnaeus and Darwin back into it for just a minute because I'm fascinated with the Gallus genus at the moment. Do you think modern day chickens, with all their diversity, are just a product of 8000 years of domestication and selective breeding of Gallus gallus or do you think there was some biological hybridization going on with another species or two of Gallus early on? And, do you think that level of hybridization (the introduction of bloodlines from a completely different species of Gallus) has occurred in more recent times to create any of the breeds we know and love today?
You need to discuss this with Resolution (BYC screen name). This is his area of expertise which he has studied and written on for years. I do not have answers for you. I ask Resolution to learn about this.
https://www.backyardchickens.com/ne...erence=recency&containingforum[0]=14&type=all
Just search by Username. He has written a bunch on this just at BYC.
Here is the URL to a list of 253 posts by Resolution: http://tinyurl.com/lkonfjq

The grey junglefowl is pretty rockin':
http://upload.wikimedia.org/wikipedia/commons/b/b6/Gallus_sonneratii_(Bandipur).jpg

The green junglefowl is interesting:
http://upload.wikimedia.org/wikipedia/commons/1/1b/Stavenn_Gallus_varius_0.jpg

And check out the Sri Lanka junglefowl:
http://upload.wikimedia.org/wikiped...Ceylon_Junglefowl_(Gallus_lafayetii)_Male.jpg

Here are some of my fav "technical" books on poultry and animal breeding.
Technical in the sense they dispense fact and not opinion.
Ms. Derry specializes in the history of animal breeding. This is her first book:
Bred for Perfection: Shorthorn Cattle, Collies, and Arabian Horses since 1800
Margaret E. Derry
http://tinyurl.com/lqbwmy3 http://tinyurl.com/lkvcmaw
And this is the sequel:
Art and Science in Breeding: Creating Better Chickens
Margaret Derry
http://tinyurl.com/lz4hvvq
Here are two other technical books by another fav author of mine.

The Genetics of Chicken Colours - The Basics
by Sigrid van Dort - David Hancox and Friends.
http://chickencolours.com/
"Chicken Colours" latter half is a superb pictorial encyclopedia captioned by the genotypes.
Genetics of the Chicken Extremes
by Sigrid Van Dort
( same website)
( this is a translated page. "Extremes" refers to the extremities of the chicken.
Not to extreme chicken breed types). This book is a bit more technical and covers
everything other than plumage" in chicken genetics. There is a downloadable PDF on the
webpage of the 1st 6 pages of this book.

Then there is the invaluable :
American Poultry Association Standard of Perfection
http://www.amerpoultryassn.com/store.htm
The 1st 40 pages are so very instructive.

Best,
Karen

 

[toucan]

Hey Karen

Thanks! I will check out all of the books and sources. I'd love to produce something cool and different once I'm all set up down here. I used to do a lot of captive breeding of reptiles (mainly snakes) and it will be interesting to see how similar or different chicken genetics are.

mike

 

[3riverschick]

Hey Karen

Thanks! I will check out all of the books and sources. I'd love to produce something cool
and different once I'm all set up down here. I used to do a lot of captive breeding of reptiles
(mainly snakes) and it will be interesting to see how similar or different chicken genetics are.

mike

More than welcome. I spent 15 years in the dog world breeding collies. Retired the kennel in 2009. I found poultry
to be a whole different world. Esp. because in poultry the male has XY and the female XX. Plus all the sex linked genes.
And ...the fact ratios and placement of color aren't optional, they are in the Standard.
Poultry are much harder to breed than dogs, smile. But.. they make us breakfast...and...we get to eat our mistakes!
Best,
Karen