Bulldogs, inbreeding, and correlated response

By Razib Khan | November 25, 2011 1:56 pm


Last of the Spanish Habsburgs

The New York Times has a long piece out, Can the Bulldog Be Saved? To a great extent it is a parable of the problems with purebred dogs. Domestic dogs are much more homozygous than humans. That is, for their two gene copies they are much more likely to exhibit similarity than humans. This is usually due to inbreeding, where a few ancestral dogs with the required traits are bred, and then selection operates upon the progeny to reduce the effective population size even more. This means that many dog breeds are in danger of pedigree collapse, where they are so inbred that going back enough generations results in a convergence of the family tree.

But the story of the bulldog isn’t just about inbreeding: it’s about correlated response. If you select upon a trait of interest, you generally produce side effects due to pleiotropy. That is, you shift the allele frequencies at locus X, which produces the outcome you want on trait 1, but also incidental outcomes on trait 2 to trait n. As stated in the piece: “Bulldogs could be as outbred as mongrel dogs in the streets of Calcutta, but if they keep that phenotype, they are not going very far.” The bulldog is profoundly unnatural in shape and gait. In other words, the issues here are not just genetic, but they’re biophysical.


In other news, Sheril just brought home a dog from the shelter. The little dude needs a name, so go on over and offer up some suggestions!

CATEGORIZED UNDER: Genetics
MORE ABOUT: Genetics
  • Cathy

    As an alum and current grad student at UGA, the article really struck home. (I mean, I have a framed portrait of #8 on my wall and everything.) That said, I wish the Seiler family would abandon the current Uga line and start from scratch. The dogs just aren’t healthy, and right now they’re acting as a miserable extended metaphor for the budgetary system and Board of Regents for the university: sure our campus looks great, but what’s the point of all those new buildings if they can’t afford to hire professors to fill them? Same thing with Uga. Sure, he’s cute, but what’s the point of a mascot if he is so sick he is going to die within a year? It’s heartbreaking.

  • Tom Bri

    The problem isn’t simply inbreeding, but inbreeding without selection for vitality. If bulldogs had continued being used to bait bulls, a dangerous sport requiring speed, agility, endurance and general all-around toughness, I doubt they would be in the state they are.

    But, then dog breeders would have a much harder time getting the ‘ideal’ conformation. Those squashed faces and bowed legs would doom a dog in the ring. These breeders are every bit as cruel as dog-fight fans.

  • Justin Giancola

    “These breeders are every bit as cruel as dog-fight fans.”

    In many ways this is a true statement.

  • http://www.propithecus-verreauxi.com rich lawler

    In the NOVA show about “decoding dogs” they mentioned how fur patterns change when tameness and docility are selected for. This was part of that famous “Russian Silver Fox” study–selection for human-friendliness and non-aggression brought about markings that are quite similar to a border collie: white stripe down center of the face and lighter underbelly, paws, and withers. So in foxes (and perhaps dogs) there is a correlation between behavioral traits and fur regions, but it would be interesting to see if this correlation is symmetrical: can selecting for whiter extremities produce gentler dogs? There must be lots of literature on “one-way” genetic correlations (selection on one trait drags along another trait but not vice versa) but I’m not familiar with it.

    Name the little fella “Muscles” or “Talisker”

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    #4, p-ter at gnxp.com posted some research a few years back with negative results on the behavior/pigment correlation. also, jason malloy looked at the nlsy data set for eye color and behavior, and didn’t find anything. though i believe that there’s stuff on blue eyes and shyness in the literature. the main thing to do would be look at siblings. that controls for genetic background, and pigment is large enough QTL that there’s difference across siblings….

  • Darkseid

    Watson (in honor of James watson)

  • Kiwiguy

    How about Algernon?

    http://dognamez.com/dog-name-meanings-of-Algernon.php

    I think Bernie suits him too.

  • http://www.astraean.com/borderwars/ Christopher@BorderWars

    Excellent, now you’re speaking my language Razib. This general topic (the genetics and ethics of dog breeding) is about half the content on my BorderWars blog.

    Some posts you might find interesting:

    When you say “The bulldog is profoundly unnatural in shape and gait. In other words, the issues here are not just genetic, but they’re biophysical” you are touching on an area that I have dubbed “Sine Qua Non Disorders” in dog breeding, where the dysfunction is not strictly a deleterious genetic disease, but a biophysical trait that has actually been selected for and is often a trademark of the breed.

    http://www.astraean.com/borderwars/category/health-genetics/sine-qua-non-disease

    You can see that there is quite a list of breeds and associated disorders that are amazingly not considered deleterious by the fancy. The DACH countries have actually taken legal steps to outlaw many of these breeding fads and practices as “qualzucht:” literally ‘torture breeding.’

    While there is a certain AR bent to this discussion that my Libertarian philosophy dislikes, there is a serious extant problem in purebred dogs and their twisted ethics on this issue that does need to be addressed (hopefully not with HSUS funded AR legislation).

    The general level of genetic knowledge among dog breeders is horrible, so I have taken up the charge of trying to distill these concepts into posts that open minded breeders could understand. I recently covered Pedigree Collapse:

    http://www.astraean.com/borderwars/2011/10/pedigree-collapse.html

    And have spent a number of posts trying to rectify the intentionally twisted understanding of inbreeding that most breeders put out as fact:

    http://www.astraean.com/borderwars/category/health-genetics/inbred-mistakes

    Sadly, even the trained biologists PhDs who are also dog breeders have a tendency to drink the show ring koolaid versus the rationalism of science:

    http://www.astraean.com/borderwars/tag/tollers

    I’ve even called out one researcher for Academic Fraud given that her personal investment as a breeder of a rare (and highly inbred) breed, the Nova Scotia Duck Tolling Retriever, led her to manipulate population genetic data to suggest that the breed was not inbred (basically truncating all but 4 ancestor generations worth of pedigree data to lower COI calculations).

    It’s a crazy little niche to be writing for, that’s for sure.

  • ackbark

    “qualzucht:” literally ‘torture breeding.’

    Like those cats with the two-inch long legs.

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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