Re: dog breeds: same species or not

John Wilkins wrote, On 07/12/07 09:28 PM:
Cj <Cj@xxxxxxxx> wrote:

"Yakov" <iler.ml@xxxxxxxxx> wrote in message
news:4d6e5538-8817-4044-95d8-eaac04a8b92b@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
As an argument against evoluiton, it was pointed out that
with all massive human activity at breeding animals and plants,
no new species was ever created as a result of domestication and
artificial breeding.

I want to ask: large dogs like St.Bernads, and smallest dogs like
Chihuahua... can they mate naturally between themselves, can they ?

I think they can't, based on their enormous size difference.

Does this not make them different species -- large dogs vs small
dogs ?
Ability to mate is most important aspect of a telling species apart,
no ?

Thanks
Y.L.


In my opinion wolves and dogs are virtually separate species for a variety
of reasons. Although it can be argued that they are interfertile the
reproductive separation of wolves and dogs is increasingly apparent because
of evolved behavioral characteristics as well as morphological differences.
In wolf-like dogs the two species can be readily distinguished by skull and
dental morphology. Wolves have a proportionately broader skull and much
larger teeth although the dental count is the same.

It appears, from genetic studies, that in the past 15,000 years there have
been four separation, or domestication, events with gray wolves.
There are no data suggesting that dogs were derived from southern Asian or
Indian wolf species. The most common interaction between coyotes, dogs and
wolves has been lethal for the former two although at least one variety of
wolf (the red wolf) appears to have been derived from a distant wolf/coyote
cross. The behavioral differences are as profound as the anatomical ones
and dogs retain some ability to recognize and respond to wolf body language
signals. The social organization of the two species is quite different.
There is a contingent of dog breeders and trainers in North America who
believe that the social organization of dogs is the same as wolves but this
is belied by socialization differences between the two species. In general
genetic wolves are extraordinarily difficult to socialize to humans and the
timing of behavioral and anatomic development and maturation is very different. The variation between different wolf species is less pronounced
than the variation between wolves and dogs.

Because speciation is a fuzzy logic topic when we try to compartmentalize
all kinds of animals and plants there are many more anatomic and behavioral
separations that define valid species than anatomical or genetic reproductive in compatibility.
Cj

Also, the experiments done in Russia on the socialisation of foxes
showed convergent similarities with dogs, indicating that it might be
possible to repeatedly domesticate wolves and other canids with very
similar results. For example, dingoes were clearly domesticated from the
Asian pariah dog, not wolves, and yet they can interbreed with
wolf-derived domestic dogs without trouble. Hence reticulate breeding
means that the "domestic dog" is in fact a polyphyletic group, and that
the wolf-dog group is a kind of superspecies with coyotes at the
periphery.

Darren Naish of Tetrapod Zoology had an interesting post on this:

<http://darrennaish.blogspot.com/2006/10/controversial-origins-of-domest
ic-dog.html>

in which he argued that wolves were not the ancestral species, but I
doubt that this is the whole story. Wolves and dogs do occasionally
interbreed, but behavioural (mating and social behaviour) makes this
rare, but still there is introgression both ways. I think that, given
the recency of the domestic dog, and perhaps even the pariah dog, that
the various Canis species are a classic case of in statu nascendi -
species in the process of being born. And we see this evidence for
evolution every day...

Naish mentions Carles Vilà et al.'s study of wolf & domestic dog genetics <http://www.mnh.si.edu/GeneticsLab/StaffPage/MaldonadoJ/PublicationsCV/Science_Dog_Paper.pdf>, but I don't feel he gives it enough weight. Indeed, at some points through that post, he seems to ignore the genetic evidence all together, especially where he seems to view the so-called "self-domestication" theory as an a ha! against domestic dogs being descended from wolves. He also mentions dog gene being found in coyote populations yet doesn't seem to mention anywhere how easily *all* Canis species can interbreed when brought into contact by humans (especially compared to how rarely the big cats interbreed).

Naish also admittedly glosses over Dimitri Belyaev's domestic fox programme, which produced many of the morphological changes which we see between dogs and wolves, even though the breeding programme only specifically selected for friendliness to humans, not physical form.

In any case, I agree with him that "[i]t's a lot to think about".

.

Relevant Pages

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