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Author Topic:   Do we need a better concept than species?
SteveN
Inactive Member


Message 1 of 73 (227290)
07-29-2005 10:08 AM


Hi everyone!
This is my first post to EvC, although I've been a lurker for quite a long time. Maybe I'll start with a few words about myself to let you know "where I'm coming from": I am a research scientist (biologist) by profession (virology, immunology) and deal with the evolution of viruses (HIV) in response to immune pressure on a daily basis. My interest in evolution in general is purely for fun, however, so my knowledge of the field overall is no better than that of anyone else who devours the popular works of Dawkins, Gould etc and spends far too much time here or at Talk.Origins. I am also an atheist (of the Dawkins persuasion) who, while respecting the right of anyone to believe what they want (as long as this does no harm) does not necessarily respect the beliefs themselves.
My first question here is more of a biological nature, and probably belongs in "Biological Evolution". I would like to know what the others think about the following:
I suppose most of us would agree that the concept of a species is really a convenient label used by our 'discontinous' human brains to pigoenhole something which does not actually exist in reality. Even the basic concept of an 'isolated gene pool' doesn't specify whether the isolation is due to a real genetic incompatibility or to environmental/behavioural/temporal differences which prevent a mixing of the genes. This is all well and good, because most of us know that there is a continuous gradation from one species to another and that there is no sharp cutoff dividing one species from another. The problem, as I see it, arises when we make claims for observing speciation events, because this requires a precise definition of what a species is, a difficult and fuzzy thing to do with two very closely related populations. Observations of 'macroevolution' are therefore an easy target for creationists because even the scientists cannot seem to precisely agree about what constitutes a species. I just wonder whether we might be better off dropping the concept of a species, although I can't for the life of me think of anything better. Damn this discontinuous mind!
I assume this problem has been addressed ad infinitum by those who work in the field of evolutionary biology, and I would like to know what the current thinking is.
Thanks in advance.
SteveN
This message has been edited by Admin, 07-29-2005 06:48 PM

Replies to this message:
 Message 7 by Wounded King, posted 07-29-2005 12:42 PM SteveN has replied
 Message 15 by mick, posted 07-29-2005 7:45 PM SteveN has replied
 Message 16 by Brad McFall, posted 07-29-2005 8:01 PM SteveN has not replied

  
Admin
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Message 2 of 73 (227315)
07-29-2005 11:22 AM


Thread moved here from the Proposed New Topics forum.

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Jazzns
Member (Idle past 3912 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 3 of 73 (227321)
07-29-2005 11:39 AM
Reply to: Message 2 by Admin
07-29-2005 11:22 AM


Eliminate All Species!!
I think we just need to drop the term species. I am sure the various professionals on the board will correct me if I am wrong but the ToE does not need a concept of species. Species are just a product of our need to categorize things when it reality they are just a continuous gradient. Lets just forget all this nonsense about trying to show macroevolution. There is no such thing as macroevolution, we are all just living things that produce offspring down the line.

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Replies to this message:
 Message 4 by randman, posted 07-29-2005 12:06 PM Jazzns has replied
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 Message 6 by SteveN, posted 07-29-2005 12:21 PM Jazzns has replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 4 of 73 (227342)
07-29-2005 12:06 PM
Reply to: Message 3 by Jazzns
07-29-2005 11:39 AM


Re: Eliminate All Species!!
So we should drop the verifiable concept and classification of an observable reality, though elastic, in favor of adopting and further strengthening belief in a non-observable hypothetical you guys beleive is reality?
And you call this good science?

This message is a reply to:
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Chiroptera
Inactive Member


Message 5 of 73 (227350)
07-29-2005 12:14 PM
Reply to: Message 3 by Jazzns
07-29-2005 11:39 AM


Re: Eliminate All Species!!
I wouldn't go that far. It is true that categories are usually artificial, but categories are nonetheless useful in organizing data. One simply has to keep in mind the limitations of one's categorization.

This message is a reply to:
 Message 3 by Jazzns, posted 07-29-2005 11:39 AM Jazzns has replied

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SteveN
Inactive Member


Message 6 of 73 (227355)
07-29-2005 12:21 PM
Reply to: Message 3 by Jazzns
07-29-2005 11:39 AM


Re: Eliminate All Species!!
Jazzns writes:
I think we just need to drop the term species. I am sure the various professionals on the board will correct me if I am wrong but the ToE does not need a concept of species.
Well, I agree that the ToE does not need a concept of species per se (despite the title of the Darwin's mighty original work), but it is a pretty useful thing to have for everyday, run-of-the-mill stuff. It's when you're looking at the boundaries between closely related populations that things get a bit iffy, and it seems to me that trying to defend a 'macroevolution' or 'speciation' event leaves us open to the same sort of criticism we often level at the creationists who are trying to define a 'kind' (though not at the same level of confusion, of course!).
Cheers!
SteveN

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 Message 3 by Jazzns, posted 07-29-2005 11:39 AM Jazzns has replied

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 7 of 73 (227369)
07-29-2005 12:42 PM
Reply to: Message 1 by SteveN
07-29-2005 10:08 AM


I don't have any problem with people using species provided they make the neccessary effort to put it into the proper context. Problems only arise when people fail to make it clear how they are using the term. Failure to diferentiate between solely morphologically defined species such as we see in the fossil record and the extant species we study today on whom we have much more in terms of genetic data, and potentially interfertility, only leads to confusion.
Similary failing to differentiate between the different forms of reproductive isolation, such as geographic isolation or pre- and post- mating isolation, can cause a lot of disagreement on what constitutes a real incidence of speciation.
I think most scientists within a field can usually agree on what a species is, it is between the different fields that differences arise as the differing definitions are obviously biased towards the interests of the particular fields. Provided the particular context is made apparent there should be no need for confusion.
TTFN,
WK

This message is a reply to:
 Message 1 by SteveN, posted 07-29-2005 10:08 AM SteveN has replied

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SteveN
Inactive Member


Message 8 of 73 (227454)
07-29-2005 3:27 PM
Reply to: Message 7 by Wounded King
07-29-2005 12:42 PM


Wounded King writes:
Similary failing to differentiate between the different forms of reproductive isolation, such as geographic isolation or pre- and post- mating isolation, can cause a lot of disagreement on what constitutes a real incidence of speciation.
Yes, that was my point, particularly the bit about.....
I think most scientists within a field can usually agree on what a species is, it is between the different fields that differences arise as the differing definitions are obviously biased towards the interests of the particular fields. Provided the particular context is made apparent there should be no need for confusion.
.....because if there's a consensus within a field as to what comprises a speciation event, that is fine for those working in the field. But it's not very satisfying when you're trying to claim an observed case of macroevolution to people who know nothing of science, particularly if different fields have conflicting definitions ("Gosh, even you scientists can't agree, so why should we believe any of you").
While we're on the subject, are there cases of 'observed speciation' (i.e. in populations living at the present) which would satisfy the criteria of most evolutionary biologists?
Cheers!
SteveN

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 Message 9 by Chiroptera, posted 07-29-2005 3:43 PM SteveN has replied

  
Chiroptera
Inactive Member


Message 9 of 73 (227465)
07-29-2005 3:43 PM
Reply to: Message 8 by SteveN
07-29-2005 3:27 PM


quote:
While we're on the subject, are there cases of 'observed speciation' (i.e. in populations living at the present) which would satisfy the criteria of most evolutionary biologists?
Yes.
Also.

This message is a reply to:
 Message 8 by SteveN, posted 07-29-2005 3:27 PM SteveN has replied

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SteveN
Inactive Member


Message 10 of 73 (227511)
07-29-2005 4:41 PM
Reply to: Message 9 by Chiroptera
07-29-2005 3:43 PM


Thanks Chiroptera
I had actually read these two articles a year ago or so, and don't in any way dispute the fact the speciation events have been observed. However, from the first article we have statements such as....
What evidence is necessary to show that a change produced in a population of organisms constitutes a speciation event? The answer to this question will depend on which species definition applies to the organisms involved.
I'm quite happy to trust the experts in their field when they say a speciation event has occurred, but others might be less inclined to do so, hence my initial post. Actually, some of the examples in the links you gave in which two separate populations are totally unable to successfully mate probably would satisfy even the most stringent of criteria, I must agree.
I guess that, as a scientist, I sometimes find it a bit disconcerting that the definition of a species may hinge on stochastic events. For example, the famous ring-species (gulls, salamanders etc) must be viewed, I suppose, as one species because although the two populations at the 'join' do not breed with each other, there is no barrier to genetic information 'going the long way around'. However, if the intermediate populations were to go extinct these genetic bridges would be burnt and one would have two genetically isolated populations, i.e. species. It seems somehow perverse that a 'speciation event' could result from nothing more than the death of animals from other populations! To give another, much discussed example, if all dogs apart from Irish wolf hounds and chihauhas were to disappear, a Martian zoologist would probably define the remaining dogs as two separate species (I'm assuming that Irish wolf hounds and chihauhas can't breed, but I might be wrong - the mind boggles!).
Like I said in my OP, I can't think of any better system than the one we already have, a system which is perfectly adequate for most of the time. I remain, however, a little uncomfortable with the current definition(s) of a speciation event. I wouldn't like to be accused of 'moving the goalposts', a common tactic of the YEC's I particularly dislike.
Bye for now!
SteveN

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Jazzns
Member (Idle past 3912 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 11 of 73 (227514)
07-29-2005 4:45 PM
Reply to: Message 4 by randman
07-29-2005 12:06 PM


Re: Eliminate All Species!!
How very condescending of you.
Where it makes sense to use the classification system it should be used. In discussion with ignorant creationists, terms like macro-evolution and species should be avoided because nature does not work in descrete classifications. All it serves is to promote confusion in the already misinformed and allow avenues for argument without basis in reality.
This message has been edited by Jazzns, 07-29-2005 02:45 PM

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Jazzns
Member (Idle past 3912 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 12 of 73 (227516)
07-29-2005 4:47 PM
Reply to: Message 5 by Chiroptera
07-29-2005 12:14 PM


Re: Eliminate All Species!!
I should have clarified. I am sure there is a good reason to use species classification in aspects of study but with regards to the definition of evolution or in discussion with creationists it does seem to only hinder rather than help.

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Jazzns
Member (Idle past 3912 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 13 of 73 (227519)
07-29-2005 4:50 PM
Reply to: Message 6 by SteveN
07-29-2005 12:21 PM


Re: Eliminate All Species!!
Yes I agree. I mostly said it with regard to how we handle describing evolution. My first introduction to evolution what the whole distinction between micro and macro. These can be really misleading concepts especially with regards to the EvC debate. Lots of useless nitpicking over things that do not represent reality can happen with regards to imporper definitions of these terms which is totally influenced by the definition and concept of species.

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futzman
Inactive Member


Message 14 of 73 (227572)
07-29-2005 7:19 PM
Reply to: Message 13 by Jazzns
07-29-2005 4:50 PM


Re: Eliminate All Species!!
Well, I'm not a biologist or taxonomist so you can take what I say with a grain of salt. But I've been thinking about this for a while now in terms of object libraries (I'm a software engineer by profession). Modern object libraries are most commonly organized using namespaces based on two criteria:
1) inheritance (class A inherits attributes and behavior of class B)
2) interfaces
Note that class B may inherit and possibly override aspects of A (the class from which it is derived) but may also just use the aspects of A as designed by A. Interfaces roughly correspond to building blocks that are there for all classes to use and may be also be overriden. Although a terminal derived class could be thought of as a "species", it's not since it may usually be derived from at some later date as deemed necessary. That's why class hierarchies use a dotted notation for denoting a class (at any arbitrary level). Interfaces are not really relevant to the definition of a "species" in class libraries. They are just noted in the class definition itself (ala B implements interface X). It seems reasonable to my simple mind that phylogenetic trees could be treated in a similar manner to object-oriented class libraries with some minor modifications.

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mick
Member (Idle past 4987 days)
Posts: 913
Joined: 02-17-2005


Message 15 of 73 (227582)
07-29-2005 7:45 PM
Reply to: Message 1 by SteveN
07-29-2005 10:08 AM


SteveN writes:
the concept of a species is really a convenient label used by our 'discontinous' human brains to pigoenhole something which does not actually exist in reality.
Hi SteveN,
Excellent question, and I hope this starts off an interesting discussion.
Species are not simply imposed on "continuous" nature by our "discontinuous" human brains. If species are imposed on nature by humans, they are also imposed by every species of metazoa living on the planet. For example, pigeons don't try to mate with jackdaws. Bees don't try to mate with wasps. Furthermore, many organisms are highly specific in the species that they use as food (I'm thinking anteaters and humming birds here).
I am willing to grant that these species categories are not "real" in a biological sense, but if they are imposed on nature they are imposed on nature by any species that mates sexually - not just humans.
Mick

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