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Starman
SFN Regular
Sweden
1613 Posts |
 Posted - 10/06/2006 : 00:52:19
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Darren Naish : Tetrapod Zoology - Controversial origins of the domestic dog quote:
Many papers published on the subject of domestic dog origins state flatly that ‘the derivation of domestic dogs from the wolf is well established on behavioural and morphological grounds', without actually saying in detail what these behavioural and morphological grounds are.
It's certainly true that domestic dogs and wolves are morphologically and genetically similar, but they're actually also notably different, and while they share behavioural traits, they also differ profoundly in some important respects.
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While (to my knowledge) no-one doubts the idea that domestic dogs and wolves are close relatives, firm evidence showing that domestic dogs are nested within the species Canis lupus is lacking.
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HalfMooner
Dingaling
Philippines
15831 Posts |
 Posted - 10/06/2006 : 02:00:00 [Permalink]
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quote:
Originally posted by Starman
Darren Naish : Tetrapod Zoology - Controversial origins of the domestic dog quote:
Many papers published on the subject of domestic dog origins state flatly that ‘the derivation of domestic dogs from the wolf is well established on behavioural and morphological grounds', without actually saying in detail what these behavioural and morphological grounds are.
It's certainly true that domestic dogs and wolves are morphologically and genetically similar, but they're actually also notably different, and while they share behavioural traits, they also differ profoundly in some important respects.
...
While (to my knowledge) no-one doubts the idea that domestic dogs and wolves are close relatives, firm evidence showing that domestic dogs are nested within the species Canis lupus is lacking.
I've actually read about this matter a bit. Please bear with me, however, as my memory of what I read is less than perfect, and I did not keep good references, since my research was merely for the purpose of a novel I was researching. Though it's become very clear now that dogs descend from Eurasian gray wolves, it's not known for certain what subspecies of wolf they came from. One isolated quote I had saved says: quote:
“The domestic dog is an extremely close relative of the gray wolf, differing from it by at most 0.2% of mtDNA sequence....
In comparison, the gray wolf differs from its closest wild relative, the coyote, by about 4% of mitochondrial DNA sequence.”
Robert K. Wayne, Ph.D.
More importantly, though dogs were beings shown as essentially genetically identical to wolves just a few years ago (in mitochondrial DNA), genetic comparison is now a much more effective science, even though little enough is known about what the particular genetic variations mean in terms of their effects. Recently, at least one dog, a female Boxer, had its nuclear DNA sequenced. But little is known about that genetics, and I don't know if the gray wolf has been sequenced, or its nuclear DNA sequence compared to the dog.
Just a handful of genes separate Homo sapiens from chimps, yet these make for some huge differences. I think it's likely the same thing is going on with dogs vs. wolves. Dogs (Canis familiaris) and wolves (Canis lupus) can and do interbreed. But many of the canid species can interbreed, as with gray wolves and coyotes. Species don't just define animal groups that can't interbreed, but mainly define groups that usually don't, due to habits, etc. Differences in coming into heat and associated mating patterns and their timing largely prevent widespread mating between dogs, wolves, and coyotes.
Species within a related genus are subject to a somewhat subjective judgement. But I'd consider the wolf and coyote to be separate species, as well as the dog and wolf. In behavior and morphology, many dog breeds are far more different from the wolf than the wolf is from its cousin the coyote.
I'll try to get back to this discussion again soon, and with some links. It's right up my alley in terms of interest, if not real expertise.
[Edit: Spelling]
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
| Edited by - HalfMooner on 10/21/2006 22:05:24 |
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Vegeta
Skeptic Friend
United Kingdom
238 Posts |
Posted - 10/28/2006 : 03:37:24 [Permalink]
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"Dogs (Canis familiaris) and wolves (Canis lupus) can and do interbreed."
Aren't dogs canis lupus familiaris and wolves canis lupus lupus?
If the question is simply 'are dogs wolves', then no, but if its a debate about whether domestic dogs are the same species or a sub-species of wolves then each case is arguable. The way I interpret it is that if two groups are genetically very similar but seperated by morphology and behaviour and, although possible, would not likely interbreed then they can be considered a sub species. The real question is when does something cross the line from being a different subspecies to being a different species? I'd say that while different breeds of dogs can be wildly different, they cant qualify as sub-species because if you placed them all in a large group the breeds would not single eachother out for mating. in a few generations you would have all mongrels. Pretty much like humans would be if not for social and geographical boundaries. However wolves and dogs would stay apart, which makes them distinct enough to be seperate sub-species.
wikipedia:
Sub-species:
1. Members of the group are reliably distinguishable from members of other groups. The distinction can be made in any of a wide number of ways, such as: differently shaped leaves, a different number of primary wing feathers, a particular ritual breeding behaviour, relative size of certain bones, different DNA sequences, and so on. There is no set minimum 'amount of difference': the only criterion is that the difference be reliably discernable. In practice, however, very small differences tend to be ignored.
2. The flow of genetic material between the group and other groups is small and can be expected to remain so because even if the two groups were to be placed together they would not interbreed to any great extent.
Because they are so similar genetically, being nearly indistinguishable, I don't see there being a case for them being seperate species. Especially since cross breeding yields a high success rate, with fertile offspring.
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What are you looking at? Haven't you ever seen a pink shirt before?
"I was asked if I would do a similar sketch but focusing on the shortcomings of Islam rather than Christianity. I said, 'No, no I wouldn't. I may be an atheist but I'm not stupid.'" - Steward Lee |
| Edited by - Vegeta on 10/28/2006 03:40:08 |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 10/28/2006 : 08:24:59 [Permalink]
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Dogs and wolves don't interbreed in the wild.
That puts them, at the least, at the border of a speciation event. Come back and check on them both in another 10k-20k years and the differences may be distinct enough to prevent interbreeding at all.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 10/28/2006 : 12:01:57 [Permalink]
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At this stage in biological science, there are no well-defined scientific rules to speciation. That's the main problem here.
Instead, biological science has a whole grab-bag of factors to consider, including genetic ability to interbreed, opportunity to interbreed, compatibility of mating behaviors, physical overlap (or lack of it) in the ranges of the critters, observation of hybrids, and real-life observed interbreeding.
No formal system of giving weight to these and other factors is scientifically agreed upon. Thus, the endless speciation debates in biology highlight one of the weaknesses of the field, by displaying this lack of agreed definition of terms. But to be fair, the definition of speciation is not a trivial problem.
You say dogs and wolves are the same species, I say they are separate. But neither of us can prove our point, simply because the term, "species" is so poorly defined.
Your argument, Vegeta, that the ability for dogs and wolves to interbreed makes them the same species is somewhat weakened by your (correct) argument here that some breeding is possible between members of different genera, as between Asian and African elephants. (If breeding is possible between genera, then interbreeding by itself can hardly be used to redefine two species in the same genus as one species.)
But that doesn't prove you are wrong in the present instance. It only shows that we don't have the definitions we need to argue about this with any chance of coming to an accepted conclusion.
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
| Edited by - HalfMooner on 10/28/2006 12:04:02 |
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Vegeta
Skeptic Friend
United Kingdom
238 Posts |
Posted - 10/28/2006 : 12:08:08 [Permalink]
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| I agree with what you're saying but I have to make clear that my point about interbreeding was not just that it is possible, but that it has happened frequently, and results in fertile offspring. Also I don't consider that the sole basis of defining a species. |
What are you looking at? Haven't you ever seen a pink shirt before?
"I was asked if I would do a similar sketch but focusing on the shortcomings of Islam rather than Christianity. I said, 'No, no I wouldn't. I may be an atheist but I'm not stupid.'" - Steward Lee |
| Edited by - Vegeta on 10/28/2006 12:09:08 |
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