Poodle Diversity Project - Blog

  • Reality Check #2

    More questions and answers regarding the latest research on Standard Poodles. 

    Question: If sebaceous adenitis and Addison's are genetic, why don’t they follow a pattern, and sometimes seem to appear out of nowhere?

    Answer: The diseases are based on complex genetics so their appearance seems more random. Breeders are more used to single gene disorders. A single gene disorder is either dominant or recessive, and for a dominant, if the parent has the gene, that parent is affected and it passes that down to, statistically, half its puppies who will then be affected. For a recessive, both parents have to have the gene, and every puppy who inherits both dam’s and sire’s disease gene will be affected, roughly 1 in 4 of their puppies. These kinds of diseases are easier to understand and easier to see. PRA is this kind of disease. NE and vWD are like this as well - simple diseases with obvious modes of inheritance.

    With complex diseases, especially those that can be triggered or made worse by some environmental influence, the pattern is not as clear. Some dogs may carry all the genes necessary and never have clinical symptoms. Sometimes the onset is late and sometimes early. Some dogs produce one in 40 puppies. Some produce one in every litter. These are all the things that make the genes hard to pinpoint as well, and the randomness that drives breeders crazy, wondering if they fed the wrong food or stressed the dog out or vaccinated dogs too much or too quickly.

    When a disease is controlled by genes at a single locus, like  a simple dominant or recessive gene, there’s still an element of chance as to whether a dog will inherit the bad one or two genes. Can you imagine how much more of a chance there is when a dog has to inherit more than two genes to have the disease? This is why complex diseases tend to be rare in populations with no inbreeding, and far more common where there is historical inbreeding, like a isolated population of humans or any other animal.

    When a population starts seeing more and more of a complex disease that should be rare, it means the genes responsible for the disease are common in the population. We do not, for instance, see necrotizing meningoencephalitis in poodles, which is a well known autoimmune disease that affects many pugs. Since these are both the same species, if these complex diseases were not genetic, we would see these kinds of specific autoimmune diseases at the same rate in different dogs. The clue as to genetic basis is not whether a disease appears in a population, but rather how frequently it appears in a population.



    Question: Will the data change over time? If so, does that mean the data isn’t valid?

    Answer: No, the data gathered right now is the data gathered right now. No dog’s alleles will change. What may happen is that the FREQUENCIES of the alleles - how common or uncommon they are in the population will change. These frequencies may change very slightly as the database grows, but they will not change enough to conclude anything different about the population structure or breeding recommendations. The sample set was extremely large for a study of this kind, and comprised hundreds of full Standard Poodles from different countries and pedigrees. The vast majority of Standard Poodles are genetically very similar, and a minority of dogs is different from them and each other. A genetically healthy population with well managed diversity will be more evenly dispersed.  

    The only way frequencies will change substantively is from generation to generation. If breeding practices that are currently used do not change, we can expect the common alleles to become more common and the rare alleles gradually to become extinct. Once gone, there is no way to get new ones without bringing them in from a different variety or breed, so we  have a vested interest in not letting that happen.

    If breeding practices change because breeders want to preserve the breed as it is, while reducing risk for disease, then the rare alleles will become less rare and the common alleles won’t be quite as common and the diversity will become more evenly distributed. The goal is not to favor any specific rare alleles, or disfavor any common alleles, but to breed so all the alleles are all in a medium range of frequency. This can and should be done while selecting for type, temperament and health. This will take a number of generations to achieve.

     

    Question: Are the rare alleles rare because they are worse for Standard Poodles?

    Answer: No. The rare alleles found in Standard Poodles by the Genetic Diversity Test are not disease genes so they were never specifically selected against. They are therefore rare because there was an enormous bottleneck which effectively drowned out many lines. Breeders do select for health, which would make some disease genes very rare as long as the diseases they create are obvious, and the mode of inheritance is easy to see.  However, most complex disease genes can't be detected, and are therefore difficult to select against. What has made a great many rare alleles rare has been stringent selection for aesthetic attributes. 

    Pedigrees do tell this tale. In the 1960s, there were many different lines which came from very different origins. These are often seen today only far back in maternal lines, because as we know, the basic instructions have long been to breed your best bitch to the best dog available. By the 1960s, the dogs winning most in the ring were descended from the 10 dogs of the bottleneck. Any serious breeder with a bitch from different lines bred her to one of the winning dogs, all of whom were cousins. In the next generation, they would take their pick puppy bitch, who was now half the old lines and half the winning bottleneck lines, and breed it to another dog who was mostly descended from the 10 bottleneck dogs. Their third generation would then be closer to 75% bottleneck lines, and the perfectly acceptable genes in the original bitch would slowly be bred out. In this way great old white, brown, and silver lines were essentially drowned out, and only because breeders were doing what they thought was right by improving the breed. They didn’t know that everyone else the world over was doing the same thing, breeding to the same lines and breeding out all the other poodle genes.

    Had those breeders known what we know now, they could have improved their lines more slowly and safely by selecting for desired traits from less inbred litters and gotten the type they liked without the loss of diversity.

    Question: But aren’t the alleles in Standard Poodles specific to Standard Poodles? Aren't some of these alleles rare because they are from miniature poodles? Are they evidence of other breeds?

    Answer: No. Scientifically, genetically, dogs are all the same species, canis familiaris. In essence, breeds developed from two things - isolation and selection, but they are all dogs. Thus any known alleles can be found in any dog, and many breeds have a few of the same alleles in their populations. That does not mean they are somehow mixed breeds, but rather that hundreds or thousands of years ago they had similar ancestors. Thus the alleles that are recorded in the Genetic Diversity Test are not ones that determine breed.

    Nevertheless, since each breed’s database shows the alleles found and how often they are found (that’s called frequency)  it’s not difficult to tell whether a profile is from a standard poodle or a miniature by comparing frequencies. All or nearly all the alleles that are found in the Miniature population so far are also found in full Standards, which simply reflects their shared ancestry from decades or centuries ago,  but they are found at much smaller frequencies. Many of the same alleles are also found in vastly different breeds as well, since all dogs have common ancestors, although breeds developed due to isolation and selection - first from natural forces, and later because humans got involved, bred for specific traits and eventually closed the gene pools.

    This kind of differentiation happens in nature too - both in animals and humans. Irish people look a bit different from Spanish people - both  having evolved over hundreds of generations in separate areas with different environments, and different influences coming from nearby populations - Vikings for the Irish and Moors, who were Arabs, for the Spanish. Yet we are all human and have common ancestors from tens of thousands of years ago, and we can interbreed just as dogs can because we are all the same species. Human races have very different appearances as well, but also have shared ancestries, just further back. We nevertheless have many of the exact same alleles.

    In humans there are a few significant examples of isolated populations that have the same problem dog breeds have - namely an accumulation of disease genes. The Amish, Menonite and Hutterite populations now have a database of identified genetic disorders all due to founder effects, meaning they had severe genetic bottlenecks in their populations due solely to closing their gene pool. In 2011, research showed that Hutterites comprised 40,000 people with only 89 founders, and there are 32 identified genetic disorders affecting the population. In the broad, open population of humans these conditions are either unheard of or extremely rare, but they are common in these closed populations. These so-called “plain people” aren’t alone - Cajuns and Quebecois are at far higher risk of certain diseases, as are Ashkenazi Jews and Afrikaners - who were of European origin - in South Africa. Even fundamentalist Mormon sects are starting to report rare genetic diseases. An estimated 75% of the FLDS population are descended from the two men who founded the sect in the 1930s.  These are all groups isolated by language, culture or geography. Natives of Iceland, a population of 320,000 and an estimated founding population of between 8,000 and 20,000 people from Scandinavia, Ireland and Scotland, has a dating app for their phones so they don’t inadvertently date a cousin. They too have certain common genetic diseases.

    What would help such human communities would, of course, be new genetic infusions - which should seem obvious to all of us. I imagine there could be people from within those communities who would say that humans from outside their community were not “pure” or were excluded from the “pure” population because they were somehow inferior, but if they are experiencing high rates of disease due to historical, not recent, inbreeding,  disallowing a genetic infusion would be against the best interests of their population. It would also not be very logical to be afraid to “bring in” genetic diseases from outside a population that is already riddled with genetic diseases, since the increased frequencies of the disease genes came about precisely because of the isolation of the population.

    Now I’m not saying Standard Poodles are in the same genetic situation as those closed populations, but some breeds are, and Standard Poodles could be one day too. They will be if the breed community doesn’t manage the lopsided genetic diversity still existent in the population well. If not,  we will have no option but to bring in genes from an outside population.  All those who are deeply opposed to loss of Standard Poodle traits by crossing to Miniatures should therefore be committed to preserving and balancing the existing diversity - something that cannot be done with pedigrees and COI alone.