Why are the different dog breeds not classed as different subspecies?

Discussion in 'Biology & Genetics' started by visceral_instinct, Mar 23, 2009.

  1. Fraggle Rocker Staff Member

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    Wikipedia offers a pretty good definition of "subspecies":
    The differences among dog breeds have all evolved as a result of deliberate intervention by humans. To the extent that certain breeds are identified with certain geographical areas, this is merely the result of different human populations breeding for different traits, such as the Lhasa Apsos' sure-footedness in the Himalayas, and the Anatolians' ability to protect flocks from large predators in Turkey.

    BTW, "Alsatians" are called "German Shepherds" in America.

    And poodles don't look so remarkably different if you shave them down. They were originally water-hunting dogs.
     
    Last edited: Jun 28, 2009
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  3. CapsOwn Registered Senior Member

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    Eh, sorry buddy, but no species exists called Canis familiaris. The dog is Canis lupus familiaris or Canis l. familiaris. Not Canis familiaris. The dog is in fact a subspecies. But the question is, why is the entire dog population considered part of the same subspecies, when different breeds can have radically different physical traits?
     
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  5. Fraggle Rocker Staff Member

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    This reclassification is very recent and, in my observation, has not been widely reported in the popular press. I'm a dog breeder (Lhasa Apso) so it's my business to know, but I wouldn't be so hard on people who haven't heard the news. It's the result of the explosion of genome mapping projects in the last few years, as technology continues to make the process faster and cheaper.

    Similarly, the domestic cat has been identified as Felis silvestris lybica, the Libyan subspecies of wild cat that was welcomed and eventually idolized by the Ancient Egyptians as it followed the rodents into their granaries.

    Even though wolves had spread to five continents versus the wild cats' three (Asia, Europe and Africa), they had not separated into subspecies as the cats had. But after the self-domestication of one pack of curious and tolerant individuals in China 15KYA, their descendants have had time to evolve into a subspecies. The significant differences between dogs (C. lupus familiaris and wolves (C. lupus lupus) are:
    • Contentment with the change in lifestyle from full-time hunting to scavenging.
    • A smaller brain that can be supported by the scavenger's lower-protein diet.
    • A more gregarious temperament; feral dog packs are much larger than wolf packs and domestic packs embrace multiple species including ones that a wolf considers prey.
    • Weaker alpha instinct; very few dogs fail to concede pack leadership to humans.
    It's only been 6000 years since cats self-domesticated, and they have not changed significantly from their wild cousins. (Although some writers count the domestic cat as a distinct subspecies, F. silvestris catus.)

    The domestication of both dogs and cats only happened once. DNA shows that the dogs and cats were spread by migration and trade with other tribes, rather than by domestication occurring in multiple locations. There is still a population of wolves in China whose DNA clearly identifies them as sharing a common ancestor with all dogs. And no, I can't explain why they haven't differentiated into a subspecies in all that time.
    Some species just happen to have more variability in their DNA than others, and dogs/wolves are capable of greater genetic variety than humans. Pick two of the oldest dog breeds such as the mastiff and the Lhasa Apso (what a surprise, they were the kitchen-midden scavengers of the Mongolian nomads) and there is more difference between their DNA than there is between an Irishman and a Native Australian, who have had 60KYA to diverge.
     
    Last edited: Jun 28, 2009
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  7. CapsOwn Registered Senior Member

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    Very interesting. And you are right on the genus name, sorry about that. I've seen someone abbreviate the species name when writing a trinomial name, which is why I thought that. I wasn't trying to be hard on anyone, sorry if it came across that way. But I would also like to say, a number of trinomial names are writting C. l. familiaris. But thank you, that did help to clear some things up. And again, I apologize. I have a tendency to sound harsher than I am. Oh, one last thing. They only recently marked the dog as a subspecies? I must have missed that news too. I always thought that they were part of the same species because they could interbreed for any number of generations and still produce healthy, reproducing offspring. I'm only a sophomore in high school, so I'm not exactly sure when they found genetic evidence linking the dog to having gray wolf ancestry, but it was recent you say?
     
  8. petadmirer Banned Banned

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    Dog breeds can now be analyzed through genetics. Genetic markers (microsatellite markers and single-nucleotide polymorphisms) have been analyzed and a representative sample of 85 breeds were placed into four clusters, each cluster having shared ancestors. Cluster 1 is thought to be the oldest, including African and Asian dogs.
    That is why dog breeds are differentiated if you want to share you thought on this go to wagsocial.com:thumbsup:
     
  9. Fraggle Rocker Staff Member

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    Like I said, this news was apparently not considered newsworthy by the popular press.
    That's not a valid criterion to use. We are also bird breeders and there are many bird species that can hybridize indefinitely. All of the species of Amazon parrots, all of the species of Ara macaws, most of the species of conures (genus Aratinga, outside North America they're usually mislabeled "parakeets") and many or most of the species of cockatoos have been hybridized in the pet trade for decades and the crossbreeds are now many generations deep. Even macaws, who take many years to reach sexual maturity, are into the fourth or fifth generation of hybridization. Seven parts Scarlet macaw with one part Blue and Gold macaw yields a Lavender macaw, which looks just like it sounds.

    But worse than that, it's also been proven possible to crossbreed birds from different genera. The Blue and Gold macaw, Ara arauna, can hybridize with the Hyacinthine macaw, Anodorhynchus hyacinthus, and produce healthy offspring that have been named the Collson macaw after the breeder who did it. I'm not sure any of them have yet reached sexual maturity to try for a second generation.

    The reason these discoveries are so recent is, of course, that hybridization is rare among wild animals because they often have courtship rituals that stimulate the hormones that generate the desire and/or ability to mate. Lions and tigers, for example, are genetically compatible, but tigers need to be clawed to stimulate their hormones and lions just hate that, so they can only be crossbred under controlled captive conditions or by artificial insemination.

    With domesticated parrots it's quite a bit easier. Baby birds that grow up together from the moment their eyes open regard each other as the same species. The courtship rituals of macaw species tend to be rather similar, so they will often mate rather readily with a macaw of a different species that they've been socializing with for years.
    I think the determination that dogs descended from wolves--as opposed to jackals, coyotes, or another Canis species, goes back several decades. But the discovery that they are still the same species--not to mention pinpointing the location of that original wolf pack in China--is the result of gene mapping sometime in the last ten years. It has also been determined that the dingo is merely a dog, not a distinct species or subspecies. They only go back about 5,000 years.
     

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