Do we need a better concept than species?

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.SteveNThis message has been edited by Admin, 07-29-2005 06:48 PM

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

Yes, that was my point, particularly the bit about..... .....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

Thanks ChiropteraI 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.... 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

Yes, I agree that in most cases the populations that we call species are indeed genetically isolated from any other, be it through true genetic incompatibility or behavioral barriers (mate choice etc), so the separate species exist in reality. However, I did read something the other day in Steve Jones's excellent 'Almost like a whale' (a rewrite of Darwin's 'Origin of species') in which he mentioned the case of populations of cichlids in Lake Victoria separated for thousands of generations by the female's choices of mates with different coloured markings. These would, I assume, constitute separate species by most definitions. However, more recently run-off following the introduction of agriculture has turned the once clear water rather murkey, and now the separation of the species has broken down. So it would seem that a speciation event is not necessarily final.The other thing I am uncomfortable with "species categories....imposed by any species that mates sexually.." is that most organisms on this planet are asexual (bacteria etc). Of course, most people have no need to distinguish bacterial populations on a day-to-day basis.Oops! I have to go! Bye for now.Cheers,SteveN

Hi NosyNedI don't know how many hundreds of your posts I've read in the last year or two, so it's interesting to be communicating directly at last. Anyway, you said... Yes. This is the bit about the definition of species that I feel unconfortable about. As a research scientist I'm always trying to find holes in my own arguments, because I know that if I don't, somebody else surely will and will probably make me look foolish, possibly in public. I would therefore have a hard time trying to argue that 'situation X' is a true example of speciation or macroevolution, because at these fuzzy borders it can become a matter of definition or even opinion. If a particular speciation event results in a total inability of members from two populations mating successfully, then I would be happy defending that. However, if the event is one in which members of the two populations simply prefer not to interbreed or cannot do so because of geographical or temporal separation, I would be loathe to have to defend that as a true speciation event, because a future reunification of the gene pools cannot be ruled out. As usual, these problems seem to arise from our compulsion to pigeonhole components of a continuous system (how tall is tall?).As we know, the evidence for common descent is overwhelming enough for evolution to be considered a fact and no creationist hand waving can change this. I just think that by pointing out examples of observed speciation that are not convincing to the layperson (or even to the scientists), we're providing ammunition to those looking for any possible holes in the ToE - hence my OP. Yes, I downloaded and read the original paper a few weeks ago (Science or Nature, IIRC), probably after having been given the heads-up by one or your posts. Quite fascinating. Once again, biology refuses to conform to our nice orderly classification systems.Cheers,SteveN

How very impatient of them!Seriously though, I realise that the average YEC is totally immune to any form of evidence that doesn't fit into their 'if-it-wasn't-so-dangerous-it-would-be-funny' view of reality. I was thinking more of the effect such perceived 'victories' by creationists could have on those with the ability to think rationally but without the background to appreciate that the species concept tends to break down under certain situations.In my particular field of research (AIDS), we refer to HIV as a 'quasispecies' (coined by Eigen, IIRC) because even within each infected individual there is a 'swarm' of genetic variants each evolved from (probably) a single infecting virus particle. Of course, being humans with a need to categorise everything that exists in the universe, HIV is subdivided into different clades according to their sequence homologies, but even here, nature throws a spanner in the works. For example, one long-time accepted clade was subsequently shown to be a recombinant form of two others: HIV can mix-and-match and has no respect for our carefully defined pigeonholes. I guess the whole of life on earth can be viewed as a quasispecies with great chunks now conveniently (for the taxonimist) extinct.Bye for now!SteveN

Well, you obviously misunderstand the word 'fact' when applied to science as much as you, as a creationist, probably misunderstand the word 'theory'. Here is a reasonable definition of 'fact' The evidence for common descent (and therefore evolution) more than fulfills this definition and is accepted by anyone with the ability to think rationally and objectively. The precise mechanisms of evolution (the theory) are still open to debate, but natural selection, genetic drift etc are pretty good candidates indeed. You really, really have absolutely no idea how science operates, do you?Damn! I actually promised myself before delurking that I wouldn't waste my time arguing with people with your sort of mind set. Nevertheless, here I am in my first ever thread responding to the usual drivel. Oh well. Edited to correct grammer This message has been edited by SteveN, Sat, 30-07-2005 10:02 PM

Hi Charles I know, I shouldn't have succumbed to the temptation to respond. I'll try to ignore him in future.By the way, I noticed the reference to the 'Steves' in the link you provided. I'm happy to say that, thanks to the foresight of my parents and my chosen profession, I'm lucky enough to be one of the 'Steves'. Been there, done it, got the T-shirt! (literally). Even better than the T-shirt is the paper published by the NCSE analysing the 'Morphology of Steve'. Yes! I'm co-author of a paper with Stephen Hawking and two nobel prize winners.Cheers,Steve
P.S. That's not Dan Dare you have as your Avatar, is it? If so, are you a fellow middle-aged Brit?

Hi Ringo316 I know, and I'm sorely tempted. I actually typed in a lengthy reply to randman's message 27 but then didn't post it because I didn't want to get embroiled in such nonsense. I shall try to restrict myself exclusively to constructive retorts only. The trouble with replying to the drivel is that it quickly drags everything off-topic (sorry Admin!)Cheers,SteveN

Here it is.Not exactly Nature or Science, but great for inspiring envy in your peers, nonetheless.I only vaguely remember Dan Dare from my childhood (born 1957) so I guess a more appropriate avatar for me would be Judge Dredd (I have about 15 years worth of 2000 AD in my cellar, much to the dismay of my wife.Oops! Even more off-topic. Sorry again Admin - not doing too well with my first appearance here.Cheers,SteveN

Yes, you're right. I guess a big part of a forum such as EvC or TO is to provide a source of information for non-participating interested parties. Having read the thread you linked to, consisting of reasonable and substantiated arguments from one side and (ahem) uneducated drivel from another, it occurs to me that certain anti-science contributors actually provide a valuable service: they help build a lively environment in which to refute their claims while simultaneously exposing the intellectual bankruptcy of their position. Well done chaps! Keep it up!OK. I'm off to bed. Goodnight!SteveN

Hi robinrohan Well, I guess that in the cold light of day, it might sound a bit snobbish, but it was meant rather as a tongue-in-cheek comment. Next time I'll put in the appropriate winky smiley I think that if it wasn't for the fact that virtually all of the ancestral forms are now extinct it would not be possible to make precise divisions (at the level of present day species) at all. The system, at that level, can therefore be considired somewhat arbitrary. Like I said in my OP, I can't think of a better system though.Cheers,SteveN
(who, I assure you, is in no way a snob!)

Hello ModulousI think, when you say... ....you're stating something (and very clearly, I must say) which is common knowledge to people in the field but which is, if anything, counter-intuitive to the vast majority of people. This is why I worry that 'at the borders', where the convenient and obvious classifications break down, we may be a bit premature to be making claims of 'speciation' where no irresversible separation of the gene pools has yet occurred. No idea how to do it better though.Cheers,SteveN

Aha. I confess that I hadn't realised that. Although that would be a far more realistic point of view to take (in my opinion) it would probably be even harder to defend to an evosceptic.Cheers,SteveN