If we found various breeds of dog in the fossil record, would we call them species?

nvidiot

Botanical Jedi
nvidiot
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Hi all, I asked this question in the "why evolution is stupid" thread but of course didn't get an answer from the woos, but the question has stuck in my head ever since... So as in the thread title, and with a few initial
provisions such as we didn't have domesticated dogs and say we knew nothing other than fossilized remains, would we regard a pug and a great dane as being separate species using modern morphology? Say we found several individuals all within the same strata a few million years old.

And if we did or didn't, what would that say about the definition of species that is generally used in the science community?

Pls forgive my addled posting or if I've put this in the wrong forum, I'm more than a little crook with what my partner calls man flu. :p
 
nvidiot said:
Hi all, I asked this question in the "why evolution is stupid" thread but of course didn't get an answer from the woos, but the question has stuck in my head ever since... So as in the thread title, and with a few initial
provisions such as we didn't have domesticated dogs and say we knew nothing other than fossilized remains, would we regard a pug and a great dane as being separate species using modern morphology? Say we found several individuals all within the same strata a few million years old.

And if we did or didn't, what would that say about the definition of species that is generally used in the science community?

Pls forgive my addled posting or if I've put this in the wrong forum, I'm more than a little crook with what my partner calls man flu. :p
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People with much more knowledge in the field will reply after my post, I'm sure. The first thing which comes to mind is that a few million years ago there would have been no targeted breeding of any species to the extent you see today; any analysis of the fossil record would take into account the possibility that at some point in time man began to intervene and artificially selected for various traits.

If we were to find pug and great dane fossil remnants at a time that man had not yet begun the domestication of other animals, I would assume that most would come to the conclusion that the two types could not breed and, therefore, were separate species.
 
nvidiot said:
And if we did or didn't, what would that say about the definition of species that is generally used in the science community?
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It wouldn't say anything that we don't already know. "Species" is a word that really doesn't have a precise definition, in the same way that "life" doesn't. It's a useful concept for general classifications, but there are plenty of examples of things that just don't quite fit in. Try reading about ring species, for example. As I say, species are a useful concept, but you should never make the mistake of thinking that they actually represent absolute boundaries.
 
Great question Nvidiot.

Here is a good example of exactly what you are asking and how we are dealing with it

http://en.wikipedia.org/wiki/Trilobite#Terminology

There are something like 5000 types of trilobites discovered in the fossil record. If we were doing this with dogs it would be the same process. Enough common elements and someone would realise they are from the same group. Just different members of the family
 
Yes. At least some would be described as separate species if we had reasonable numbers of each, so it was apparent adult forms varied greatly. You go on the data you have. If all you have are fossil bones and they look as different as a Pyrenean and a Chihuahua, it would take a brave palaeontologist to say they were the same species.
 
Generally I'm a splitter actually, but in my field science is a large degree by common usage and acceptance not necessarily accurate description or rencent morphological/genetic research. And many in this field are somewhat.... elder... than your typical scientist. I am of course referring to botany, specifically orchids. :P

Indeed the question somewhat arises from my experience with orchid species growing, and the facinating relationships between many otherwise distinct appearing genera. I feel these plants are some of the most convincing and powerful evidence for evolution as we understand it due to their interactions with other members of their genera/species and the extensive hybridisation record we (very luckily and with a great amount of foresight) have today. The relationships with pollinators are also an excellent educational point on converging evolutionary traits in otherwise unrelated and separated species and co-evolution as each side tries to "outwit" the other. The whole micorrhizal relationships just adds even more icing on the evolutionary cake.

I am of course aware that species is a nebulous concept, but thought this might be a demonstrative example seeing as some of the woos on here seem to regard there being something called a "kind" which sometimes has similar traits to the commonly used meaning for "species" but sometimes is a very different definition.

And indeed, given the information we would have from finding fossilised remains of two creatures so different yet we know are so well related merely separated from strong selective pressures you would be hard pressed to declare them both canis familiaris. We do this now however... is this because we are conditioned by experience of the breeding of distinct dog varieties (for lack of a better term) to know that they have come from one or two original wild species selections? Or are they still called the same species name but given a varietal name?

Sorry if this all seems a little silly as a questioning line but I'm a little hazy at the moment. Just had my bike stolen from the front of my house today and my head is pounding from some evil lurgi. Hope these posts have made sense.
 
I'm no expert on fossil identification, but if all that was found was Pekineses and Great Danes, then I'm pretty sure they'd be classed as different species. However, if there were examples of the entire range of breeds, the truth might be plainer, especially if sufficient detail was available on the bones.

Part of the problem would be having only the skeleton. The similarities are a lot more obvious when you look at the soft tissues. And histologically, you can't even tell the size or breed, it all just looks like "dog".

Rolfe.
 
Species can absolutely be defined precisely, as two animals that can breed and provide viable offspring. For instance, a mule is technically not a species going on that definition because mules are infertile.

I'm not an expert of canine osteology, but if you had a skeleton of a great dane and say a labrador, I would imagine that the greatest difference would be the size, and that basic skeletal characteristics would be the same, so they would be classified as the same species. Paleohominid remains are classified as different species most of the time because there are notable differences in the skeletal morphology, since we obviously can't determine breeding capabalities in this case.
 
It's more than just size. A brachycephalic breed like a Pekinese is a whole different shape from something like a Great Dane. It's possible someone really expert could spot it, but I wouldn't bet on it.

Rolfe.
 
I'd say that if only Pekingese and Great Dane fossils were found in a fossil record, they'd not only be classed as different species, they would in fact have to have been different species. An interbreeding population in the wild could not maintain such a size dimorphism. The notion that they "could have bred" with one another is irrelevant, if in fact they did not do so. And we would know, if we observed only Pekingese- and Great Dane-sized skeletons, that they did not do so.

The issue becomes more complex if we observed the full range of dog morphology that exists in the real world today. But even in that case, I think it would be quite reasonable to conclude that separately breeding populations -- separate species -- must have existed in order to maintain the diversity over any significant time span.

Respectfully,
Myriad
 
jillianbean said:
Species can absolutely be defined precisely, as two animals that can breed and provide viable offspring. For instance, a mule is technically not a species going on that definition because mules are infertile.
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The problem is, that's only one of the many definitions of what a species is.
 
Myriad said:
I'd say that if only Pekingese and Great Dane fossils were found in a fossil record, they'd not only be classed as different species, they would in fact have to have been different species.
Myriad
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I don't see that as a possibility, since "dog breeds are groups of animals that possess a set of inherited characteristics that distinguishes them from other animals within the same species."

DogWP
 
Difficult to answer: the line between breed and species is fuzzy. In fact there's not a single all-encompassing definition of species, because the issue is very complex.

I think that dogs of various breeds are so different that, yes, without access to their DNA or other clear evidence, finding fossils of them might lead scientists to deduce that they are of different species.
 
Emet said:
I don't see that as a possibility, since "dog breeds are groups of animals that possess a set of inherited characteristics that distinguishes them from other animals within the same species."

DogWP
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And how long would those distinct groups exist if humans stopped caring for and selectively breeding dogs? Not very long. Dog breeds exist because of human activity.

So, if we found such Pekingese - vs. - Great Dane differences in fossils from a time when humans did not care for and selectively breed dogs, "they're not separate species they're different breeds of dog" would make no sense at all as a hypothesis. Whereas "they're separate species" would account for the observations.

Too many silly counterfactuals here. "What if today's dog breeds impossibly existed in prehuman eras and left fossils? Why then, biologists would mistake them for separate species and be completely wrong!" Well yes. And if cats were cubic we'd be able to build walls out of them. So what?

Respectfully,
Myriad
 
jillianbean said:
Species can absolutely be defined precisely, as two animals that can breed and provide viable offspring. For instance, a mule is technically not a species going on that definition because mules are infertile.
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Most practitioners of biological systematics (aka cladistics) will tell you that that is not a valid defniition. There are many cases of animals classified not only as separate species in the wild but as separate genera which can interbreed, but in fact do not for various reasons. Excellent examples are the liger (species) and the cama (genera). The point is that once a subgroup of a species stops interbreeding with the parent group, for whatever reason, regardless of the fact that they might still interbreed under artificial conditions, they are then free to follow their own destinies genetically. Of course, such a definition can lead to follies like the re-integration of the groups when some ephemeral barrier is overcome, which then could erase what was a separate species, and so forth. That could be part of the story about why H sapiens has in infusion of H Neandertalensis genes, but only in part of our genome (that part that migrated to Asia and Europe). That would seem to make those with H N genes a separate species from those without, yet we know that we can easily and successfully interbreed with them. Of course the story could just as well be written in other ways, too.

The point is that precise human definitions to not drive nature; rather nature drives our apprehensions of what is really happening. That is not a weakness in our definitions, but rather a locus of logical complexity that needs to be understood better, and perhaps just lived with.

I'm not an expert of canine osteology, but if you had a skeleton of a great dane and say a labrador, I would imagine that the greatest difference would be the size, and that basic skeletal characteristics would be the same, so they would be classified as the same species. Paleohominid remains are classified as different species most of the time because there are notable differences in the skeletal morphology, since we obviously can't determine breeding capabalities in this case.
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Just so. Paleo-cladistics is robbed of the most useful tools available for determining what the real cladistics story is beyond, perhaps, 100,000 years into the past (with few exceptions), not to speak of loosing any reliable trace of what their basic criteria does to help the classifications.

That doesn't mean we should throw those tools away in cases where their use is possible just because they can't be used in all cases, nor should we have a problem that such use then requires us to notice that some declarations have lower probabilities of being right than others do. We just have to muddle through with what we have, hoping for better tools in the future.
 
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Myriad's point is very valid. You'd have to assume the breeds were being maintained by selective breeding. If dogs all ran feral, we'd be back to generic "dog" within a few generations. On the other hand, some breeds have difficulty breeding at all without human assistance (see Boston Terrier), and mating is a bit problematic between individuals with a very marked size discrepancy.

Rolfe.
 
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