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Why are there subspecies?

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Old Sunday 5th April 2009, 16:06   #1
bauer
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Why are there subspecies?

Hi there, I am quite new to birding and doing a course at the moment. I have come across the Eurasian Jay's many subspecies and understand that there are many slight variations of the Eurasian Jay, but how come? Why do they develop? Sorry, it may sound like a really stupid question, but does anyone have some clues or good explanatory websites at hand?
Thanks!
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Old Sunday 5th April 2009, 16:36   #2
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A big topic, best approached through the concept of "speciation". To get started, google "speciation" (you'll get lots of hits) & browse until you find something at your current level of knowledge/interest.
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Old Sunday 5th April 2009, 17:24   #3
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Apologies for wandering somewhat off-topic, but can somebody explain the background to the current taxonomic treatment of Homo sapiens.

I understand that H sapiens is generally considered to be monotypic. But if we can recognise 40+ subspecies of Horned Lark, then surely there are many more distinctive geographic races of Man.

Have large numbers of formally-named subspecies ever been proposed for H sapiens historically? Does the current treatment reflect concerns that subspecies recognition might have divisive or racist implications? Or is it simply an acknowledgement that, in our case, such subspecific taxonomy would be too complex/controversial to be scientifically useful?

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Old Sunday 5th April 2009, 19:31   #4
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Richard,

Very interesting question! One ive often thought about myself. On many levels the wide vareity of human "races" are quite different. Obviously visually we are all quite different. This vareity between us is heightened by the fact that we are tuned into the minute differences between us, making individual recognition possible. Im quite sure this happens in many organisms. Many social structures, even rudimentary ones, would have trouble functioning without such an ability to identify individuals.

Even so its hard to ignore the racial differences that exist in humans. Beyond the visual, differences exist on the molecular, immunological and genetic levels to some degree.

However, it should be noted that such differences take up a tiny amount of the total genetic variation thats out there.

As the only technologically intelligent species on this planet we are slightly different from every other species on the planet. We have been able to adapt to environments using technology (such as clothing and fire) with a bare minimum of physical adaptation.

Its entirely possible that, without further technological advancement, separate species of humans may have developed on the various remote regions of the planet.
But the same ability to traverse the planet has improved with time, ensuring that the flow of genetic material is constantly returning back into the central pool, no matter how far apart we get.

We are the only species with a cultural paramater (language, tradition, religion etc). And to many people that can be seen as a difference, but its important to remember that having a culture of any kind is encompassed in the realm of the human condition.

From a social point of view and from a genetic security view it makes no sense to separate humans into separate races or species. We need that genetic variety. Otherwise some pandemic or other would wipe us out.

Socially, we dont need to see eachother as different, otherwise we would wipe eachother out!!

But on the simplest level. The simplest genetically. The simplest socially. The simplest psychologically. And the simplest evolutionary....it all comes down to one little thing....sex.

The male of our species is not fussy. The cross breeding paramater, often so crucial in determining levels of speciation these days will never be satisfied in our species.

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Old Sunday 5th April 2009, 21:40   #5
StevePreddy
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Originally Posted by Richard Klim View Post
Apologies for wandering somewhat off-topic, but can somebody explain the background to the current taxonomic treatment of Homo sapiens.

<snip>

Richard
Richard

Wikipedia makes an attempt at it:

http://en.wikipedia.org/wiki/Race_(c...f_human_beings)

and there's some stuff in one of Richard Dawkins' later books - The Ancestor's Tale, I think?

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Old Sunday 5th April 2009, 21:53   #6
Rasmus Boegh
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Does the current treatment reflect concerns that subspecies recognition might have divisive or racist implications? Or is it simply an acknowledgement that, in our case, such subspecific taxonomy would be too complex/controversial to be scientifically useful?
Yes, there certainly is a significant historical aspect, as most earlier "scientists" used possible extant human subspecies primarily as an argument for why some should be considered superior over others (i.e. racism). However, disregarding that entirely, it should also be realized that most "pre-modern age" (i.e. before we were as free to move between continents as today) morphological variations within humans acted as clines, which under the "standard" subspecies concept do not justify recognition as subspecies. This, of course, still leaves isolated populations where you could argue for subspecies, but genetics suggests this is not the case. There are certain African populations where there, within the populations themself, are greater genetic variations than within remaining human populations (this, among others, leads back to all the "Ancestral Eve", "Ancestral Adam" and "out-of-Africa" theories). At least from a phylogenetic point of view, this presents a strong argument against human subspecies, as it would result in the paraphyly in the African population (of course it should be noted that there also is a discussion regarding the possibility of accepting non-monophyletic taxa). Some have then suggested that certain microsatellite variations should be used as an argument for human subspecies, but it appears most have gone against that argument.

Last edited by Rasmus Boegh : Sunday 5th April 2009 at 22:38.
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Old Sunday 5th April 2009, 22:11   #7
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so, basically we are all the same ?
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Old Sunday 5th April 2009, 22:18   #8
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By no means the same. But all the same species.

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Old Sunday 5th April 2009, 22:37   #9
fugl
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Originally Posted by Richard Klim View Post
Apologies for wandering somewhat off-topic, but can somebody explain the background to the current taxonomic treatment of Homo sapiens.

I understand that H sapiens is generally considered to be monotypic. But if we can recognise 40+ subspecies of Horned Lark, then surely there are many more distinctive geographic races of Man.

Have large numbers of formally-named subspecies ever been proposed for H sapiens historically? Does the current treatment reflect concerns that subspecies recognition might have divisive or racist implications? Or is it simply an acknowledgement that, in our case, such subspecific taxonomy would be too complex/controversial to be scientifically useful?

Richard
Prior to WWII, a number of human racial classifications were proposed & taken more or less seriously by anthropologists & others (& we all, unfortunately, know who some of the "others" were), though subsequently the subject fell into disfavor. The only (fairly) recent work that I can think of off the top of my head was by Carleton Coon, an American physical anthropologist who proposed a formal racial typology for humankind a few decades ago, arguing, if I recall correctly, that each of the modern human "races" was descended from a separate "subspecies" (I think he actually used the term) of Homo erectus. I don't think his views ever gained much acceptance in the anthropological world & nobody takes them seriously now as far as I know.

At this stage of the game, I can't imagine a valid reason for any form of formal racial classification of human beings. What on earth would be the point? Or are there "mammal watchers" out there someplace who want to tick off the various "subspecies" on their check lists?
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Old Sunday 5th April 2009, 22:43   #10
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well, if they do, I suggest they come to London, a celebration of Homo sapien diversity if such a thing exists

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Old Sunday 5th April 2009, 23:21   #11
Rasmus Boegh
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Originally Posted by bauer View Post
I have come across the Eurasian Jay's many subspecies and understand that there are many slight variations of the Eurasian Jay, but how come? Why do they develop
While I would suggest you follow the recommendation by fugl, I can add a brief and (arguably over-) simplified explanation (e.g. staying away from things like sympatric speciation): All things change. If two populations become separated from each other (e.g. by oceans or mountain-ranges), they will start evolving in different directions due to a wide range of reasons: What food is available, what type of habitat exists (forest, woodland, savanna, etc), is the habitat dry or humid, what type of predators exists, do females prefer a certain type of male, etc, etc. These and many other things are not identical at different localities, leading to the different populations evolving in different directions, and therefore eventually looking differently. In the beginning, the difference between the populations is quite small, and they are still able to breed together. They are subspecies. If they remain isolated from each other they will eventually evolve into separate species.

Last edited by Rasmus Boegh : Sunday 5th April 2009 at 23:24. Reason: typo
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Old Monday 6th April 2009, 06:58   #12
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Thanks for all the interesting replies re Homo sapiens (and sorry Bauer for partially hijacking your thread!). The Wikipedia article is very informative.

To be clear, I was not suggesting that we should define or recognise human subspecies. I was just curious about the rationale for treating our own species in a different way (although clearly we are a rather special case).

It will be interesting to see how Homo sapiens is treated in the forthcoming Handbook of the Mammals of the World.

Richard

Last edited by Richard Klim : Monday 6th April 2009 at 08:00.
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Old Monday 6th April 2009, 12:14   #13
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Originally Posted by fugl View Post

At this stage of the game, I can't imagine a valid reason for any form of formal racial classification of human beings. What on earth would be the point? Or are there "mammal watchers" out there someplace who want to tick off the various "subspecies" on their check lists?
Maybe. My friend was 'ticked off' by an immigration official when he arrived in South Africa on an Icelandic passport. The customs guard was delighted and turned to his colleague and said "at last, one from Iceland!"

Jared Diamond mentions something about six basic divisions of humanity in Guns, Germs and Steel which from memory are: whites, Asians, blacks, Pygmy, Khoisan and Australian Aboriginals.

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Old Monday 6th April 2009, 14:45   #14
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Jared Diamond mentions something about six basic divisions of humanity in Guns, Germs and Steel which from memory are: whites, Asians, blacks, Pygmy, Khoisan and Australian Aboriginals.

E
I have not read the above author, but there was a paper in Scientific American (I think -- it is about 15 years ago) which argued that if there were to be subspecies of humans, then it might be possible based on DNA to argue for about 8 subspecies among original Africans, but the rest of the world was too homogenous to separate at all. This last point agrees with what Rasmus said above: some African populations include more variation than is included when looking at europeans, american indians, australian aboriginals, and asians together.

This is not a topic I follow, but I do not think the conclusions have changed.

Cheers
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Old Saturday 11th April 2009, 11:23   #15
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Speciation

I would recomend going back to the master and reading On the Origin of Species by Darwin. I've still to read a more lucid and easy to follow explanation, but of course without the subsequent genetic confirmation.
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Old Saturday 11th April 2009, 16:53   #16
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I would recomend going back to the master and reading On the Origin of Species by Darwin. I've still to read a more lucid and easy to follow explanation, but of course without the subsequent genetic confirmation.
I couldn't agree more. The Origin is still very much worth reading for explanation of basis principles as well as for its historical interest.
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Old Sunday 12th April 2009, 17:08   #17
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If you're ever around an, "Australian" bird guide (book) - or better yet "In" Australia ---- check out the "Sitella". A beautiful bird that fills the niche of perhaps a woodpecker or nuthatch (where you live). It was once just one species. Because of the changing climate in Australia it is getting stranded in certain areas -- cut off from the rest. Things are changing with the populations (now subspecies) perhaps on the way to becoming totally different species. The books explain it best. The maps make it very clear.
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Old Monday 13th April 2009, 02:58   #18
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Here in North America we have that most adaptable of Hawks, the ubiquitous Red-tailed Hawk, Buteo jamaicensis. According to Wheeler in his Raptors of North America editions there are 13 Subspecies (he also uses the term "races") in North and Central America. 6 of these "races" seem to be limited to North America and apparently "intergrading" takes place among them where their respective ranges intersect.

Then 10,000 miles to the south in Patagonia there is the Rufous-tailed Hawk, (Buteo ventralis) which is the "spitting image" of B. j. borealis, the "eastern" North American subspecies. I believe it has been included as part of a "Superspecies" with the North American Red-tailed Hawk. It seems to be close to being put into the "near endangered" classification because of habitat problems. See Rasmus Boegh's thread #11 above.

http://www.birdlife.org/datazone/spe...p&sid=3514&m=0

This bird does not seem to be as adaptable as it's distant cousin in North America.

I wonder if it's survival potential could be improved with judicious inter breeding with B. j. borealis? Or if, indeed, it is possible.

Any thoughts on this are welcome.

Cordially,
Bob

http://www.birdlife.org/datazone/spe...p&sid=3514&m=0

Last edited by ceasar : Monday 13th April 2009 at 03:11. Reason: addenda
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Old Monday 13th April 2009, 22:48   #19
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http://www.birdlife.org/datazone/spe...p&sid=3514&m=0
...

I wonder if it's survival potential could be improved with judicious inter breeding with B. j. borealis? Or if, indeed, it is possible.
Except as an absolute last ditch effort, hybridization with closely related species is a bad idea, and one that finds very little support within the scientific community. If we're "saving" a hybrid are we really saving the species? Just look at the problems they're having with the Alagoas Curassow. In any case the situation for the Rufous-tailed Hawk isn't that bad, which is why it "only" is placed in the Near Threatened category by BirdLife International. Even if one perhaps could argue for a higher rating, it certainly doesn't come anywhere near the worst, Critically Endangered:

http://www.birdlife.org/datazone/spe...try=-2&chkCR=1
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Old Monday 13th April 2009, 23:24   #20
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Except as an absolute last ditch effort, hybridization with closely related species is a bad idea, and one that finds very little support within the scientific community. If we're "saving" a hybrid are we really saving the species? Just look at the problems they're having with the Alagoas Curassow. In any case the situation for the Rufous-tailed Hawk isn't that bad, which is why it "only" is placed in the Near Threatened category by BirdLife International. Even if one perhaps could argue for a higher rating, it certainly doesn't come anywhere near the worst, Critically Endangered:

http://www.birdlife.org/datazone/spe...try=-2&chkCR=1

Thanks for taking the time to respond. I suspect that most of the information in this particular forum is new to a lot of us who venture into it.

Just one more question, if you please? Is intergrading (or interbreeding as most of us know it) between sub species considered hybridization? Or is that limited to interbreeding between species; say, for example, between a Swainson's Hawk and a Rough-legged Hawk?
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Old Tuesday 14th April 2009, 01:29   #21
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Just one more question, if you please? Is intergrading (or interbreeding as most of us know it) between sub species considered hybridization? Or is that limited to interbreeding between species; say, for example, between a Swainson's Hawk and a Rough-legged Hawk?
A slight stray from the original subject of this thread, but I guess Bauer will manage. To answer the above; no, the term hybridzation is not limited to different species. When involving subspecies, it is, to be accurate, often referred to as intraspecific hybrids.
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Old Tuesday 14th April 2009, 16:46   #22
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I would recomend going back to the master and reading On the Origin of Species by Darwin. I've still to read a more lucid and easy to follow explanation, but of course without the subsequent genetic confirmation.
Yes - all these years of talk about Origin and it's only now that I got round to reading the original book. Struck me how much there is there to surprise and impress even a reader who considers themselves up to date!
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Old Wednesday 22nd April 2009, 11:07   #23
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Turning the question around somewhat, it is interesting to speculate why some of the members of genus Pan should be reclassifed as Homo.
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Old Friday 1st May 2009, 13:16   #24
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Richard, Pariah gave you a pretty good answer right away, but let's see if I can't boil it down to something short and simple.

H sapiens is generally considered to be monotypic because it is monotypic. Determination of "species" and "subspecies" has nothing to do with the size or number of observable differences between populations. Repeat, nothing. Species and subspecies classifications are only assigned where there is a lack of gene flow between the two populations.

In humans, there is substantial gene flow between all the various populations, so it wouldn't matter if South Africans had green teeth and feathers while Icelanders were 2 feet tall with flippers instead of ears .... if there is significant gene flow between the populations, then the question of species or subspecies doesn't even arise.

Have large numbers of formally-named subspecies ever been proposed for H sapiens historically? Yes. But the evidence didn't support them.

Does the current treatment reflect concerns that subspecies recognition might have divisive or racist implications? No. The question does not arise because there is no lack of gene flow.

Or is it simply an acknowledgement that human subspecific taxonomy would be too complex/controversial to be scientifically useful? No. Such a classification would make a nonsense of our current system of scientific classification. You'd have to revise every other classification of every other living thing. (Well, certainly the higher taxa, such as birds and mammals. At a wild guess, you'd wind up with 50,000 bird "species" with hundreds of thousands of "subspecies", and an unworkable mess instead of the current system of classification which, for all its problems, actually works quite well most of the time.)
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Old Friday 1st May 2009, 15:18   #25
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H sapiens is generally considered to be monotypic because it is monotypic. Determination of "species" and "subspecies" has nothing to do with the size or number of observable differences between populations. Repeat, nothing. Species and subspecies classifications are only assigned where there is a lack of gene flow between the two populations.
Species are indeed usually determined by a high degree of genetic isolation. But avian subspecies are typically just geographically distinct populations or races displaying different morphological characteristics (of questionable validity in many cases), often clinal or with extensive zones of intergrading - eg my earlier example of 40+ subspecies of Eremophila alpestris. I'm sure that, given the opportunity, a North American subspecies of Horned Lark would be more than happy to exchange genes with a Eurasian example. Is this really so different from Homo sapiens? (Our recent dramatically increased mobility has of course hugely accelerated this process.)

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