A perennial topic. The organisms we see cluster around specific, distinct types. We can identify an individual as belonging to that type because it has the distinctive characteristics of that type. We know what the characteristics are because we see a lot of such individuals.
To the some Creationists, those types represent essential, immutable forms, perhaps with some post-Ark latitude, and a bit of variation around the ‘norm’. It is as if those forms were cast from a mould, with small manufacturing defects. The mould is eternal, unchanging.
To the Evolutionist, those types are simply the current form of a changing lineage. Lineages can branch and diverge leading to an increase in the total numbers, offset by extinction. The branching process is somewhat extended in time, so species are not only malleable but somewhat blurry around the inception of a bifurcation. Intraspecific variation does not become interspecific variation overnight.
The Creationist demands to know how one type can ‘become’ another – how one unchanging essence can become another unchanging essence. The Evolutionist answers that their conception of ‘species’ is awry – one type becomes another, or two, gradually, changing like minimalist music. The type ‘floats on the breath of the population’, as Dr Johnson said of the unwritten Erse language. The Creationist responds that this is begging the question – defining species in evolutionary terms is an attempt to prove evolution by definition.
Nonetheless, if you are talking of evolution, your species concept needs to take account of it. An essentialist conception is no use in an evolutionary framework. There is, in my opinion, no non-arbitrary means of distinguishing species from other taxonomic ranks while interbreeding (and hence gene flow) is possible. This is the limit of the Biological Species Concept – a biospecies is the set of all the individuals which can create viable fertile offspring with at least one other member of the set. This can frequently be far too broad – maples separated for 20 million years can interbreed, and fertile hybrids between morphologically distinct types, even those assigned to different genera, are common. It is also difficult practically to assess whether the sets are ‘really’ separate yet. At the extreme, a single introgression among billions of incompatible pairings would indicate incomplete speciation, to a BSC pedant.
Creationists claim an objective means (as they do in other arenas …) but take them out in the field and I suspect their hypothetical methodology would fail them. If we base it on ‘morphology’, just how does one rank characters objectively? A wing-bar, beak colour, gregarious, particular mating dance, blue eggs, prefers shrimps … how many characters, which ones are more important, and by how much?
I would take as an example the Spotted sandpiper and Common sandpiper. These are held to be an example of parapatric speciation – they occupy different but contacting ranges, and within those ranges, for reasons unknown, gene flow in a single ancestral species between the ranges gradually diminished. Potential causes include a temporary ‘firebreak’ where no individuals penetrated, dichotomous mate preference, or ecological specialisation. Now, again for reasons not entirely obvious, they do not penetrate each others’ ranges except in narrow contact zones. At these zones, hybrids frequently occur. So on the BSC, speciation is not complete (indeed, the Common also interbreeds with sandpipers of a different genus, so on the BSC they join in too). But they are clear morphological species. Are they Platonic? Were they both on the Ark?
It seems to me that the best illustration of the messiness of the species concept is the phenomena of ring species, where adjacent species in a chain can mate but the species at the 2 ends cannot. This messiness is what we’d expect if populations and species are evolving over time.
It seems to me this also has some bearing on a topic from another tread : Barry’s bullying of people over at UD who didn’t accept his philosophical principles. Theists ( and IDists) want to cram the real world into simple abstract principles as a first step towards proving the existence of God, but this is rarely valid. In the case of ring species we see that A=B=C=D=E but A≠E …isn’t this impossible??
I’d like to see fmm provide his definition of species, as he seems to think that species is defined as “what evolution can create” as per recent comments on the Mendel’s Accountant thread.
fmm, can you provide a non-vacuous definition?
And a few questions too fmm:
Is there only one “species” of bacteria then?
If not, how do you separate one from another?
I believe that there is no properly demonstrated ring species at this point. They’ve all become at least dubious.
Glen Davidson
I thought that one was dubious but the rest are valid ( I forgot which one)
GlenDavidson,
I just read Coyne’s old post on the topic. There are no true ring species if one includes the requirement of continuous gene flow between the populations There are if one uses the relaxed definition I use above
Species is a purely human concept. If our only knowledge of dogs was from their morphology, there is no way that we would include chihuahuas and Great Danes in the same species, yet we do. Even if we define species as the ability to breed and produce viable offspring, chihuahuas and Great Danes would be different species.
Yet tigers and lions, who can breed and produce viable offspring, are classified as different species.
I haven’t given it a lot of thought. How about something like this?
species- A group of living organisms exemplifying a particular Platonic Form in the mind of God.
The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial, e.g., Homo sapiens.
no
By comparing attributes and characteristics
peace
Then the best biology should be coming out of monasteries, instead of coming from the science labs.
Why?
Do you think Platonism is the bees knees when it comes to Catholic monks?
peace
I didn’t really expect to find a definition of species, so I wasn’t disappointed. 🙂
I agree with a poster here that species is entirely a human construct and is unknow in the biology of the planet. in fact there was a discussion of this on another origin blog.
I just recently found out lions and tigers could easily breed. So not species IF reproduction is the boundary.
For a creationist or evolutionist ALL there is IS variation in a population descendent from a previous population.
Whatever the mechanism its influence brings a population change. so people have changed from NOAHS family and are called races and cats have changed from a pair off the ark and are called species. yet there is no biological mechanics difference.
Species is truly a word to be coined out of biological science. I don’t have the stripes to do it so someone else.
Creationists do, or shouldm see biology as under influence of mechanisms to have changed all biology since the fall. No crocs before the fall.
So cats are the same kind despite looks and despite ability to breed. indeed marsupial cats are just cats. Now extinct.
In fact I suspect cats include
civet cats. so the kind is very hidden.
if mechanism blurrs new populations from old ones then these lines would be almost invisible at stages. The origin of types is not explained still.
I think its unnate mechanisms acting on population in RICH envirorments. Not poor ones.
the great example is people. Peoples looks did not evolve but suddenly were triggered in a migrating population. thats the clue. We are the clue.
Mung,
Er … good.
fifthmonarchyman,
Reminiscent of Monty Python’s ‘How To Do It’ on playing the flute.
Would you not also have to compare each attribute and characteristic with the mind of God? In this case, God only knows what attributes are worth comparing.
Good. Now in order for your definition not to be vacuous you have to do something useful with it.
So compare the attributes and characteristics of the populations that evolved in Lenski’s study.
Was speciation observed?
If so why?
If not why not?
Yet you feel justified in saying that any definition of species that shows speciation was observed in Lenski’s study is vacuous.
You see, you’ve shown your hand. You know (presumably revealed knowledge) that only god can make new species and therefore evolution cannot.
And so, despite not having “given it a lot of thought” you know that any definition of species that can be demonstrated as possible for evolution to produce is automatically wrong.
Do you now see why people like you are the enemy of rationality? You know what you know and everything else is wrong. And that’s it. And you cannot be convinced otherwise and you will never change your mind.
Luckily the damage people like you can do is limited by the same lack of knowledge that defines you in the first place.
Perhaps you should look in those textbooks about evolution you occasionally pretend to have read?
This seems reminiscent of discussions on morality. There is a ‘true’ answer, to which we can never be privy.
Spotted and Common Sandpipers, then. ‘True’ fmm-species or no? Why, either way? What weight is given to each distinguishing character?
Doesn’t the very existence of a ‘species problem’ argue against Platonic essence?
It’s called thinking God’s thoughts after him.
no speciation was observed the Bacteria were still E coli. The only thing that changed was that citrate could be more efficiently metabolized.
I never made this claim I think it’s an open question
Again I never made this claim.
If you have a definition of species that is better (more objective) than mine I would love to hear it. I’m not rejecting anything out of hand. I just think defining species specifically with “evolution” in mind is sort of begging the question
peace
We can be privy both when it comes to morality and species. It’s called revelation.
no the species problem is largely the result of our abandoning the Platonic paradigm
peace
That is the sort of work that Taxonomists should be about. The goal should be to approximate true species as much as possible I would expect that we would get continue to get better as our understanding improved.
As far as weighting distinguishing characteristics off the top of my head I would say that I would give more weight to characteristics with less variation between individuals
peace
I’m beginning to see why your programming efforts are such a pathetic failure.
How do you know? What would count as speciation, can you even say?
Are you 100% sure about that? Is that the *only* change observed? Perhaps you don’t actually know as much about this as you think you do.
You have not actually given a definition of species! Unless you mean this:
If that is in fact what you claim as a definition of species, please demonstrate how we can use that when examining two organisms to determine if they are the same species or not. Demonstrate how using that you can show there was no speciation in Lenski’s experiment. You can’t, it’s impossible.
Yet that’s exactly what you are doing. Except you are saying that “species is what god originally created”. And as we don’t know what god originally created, that definition is useless.
So, if you define species as ” A group of living organisms exemplifying a particular Platonic Form in the mind of God” could you tell me how many species of bacteria there are?
One? Ten? Many?
If not, how is your definition useful or objective?
The slow progress in putting my tool on a webpage is mostly due to lack of effort on my part. The tool works just fine for my purposes. I haven’t spent much time on the web page because I busy here
If you are all interested I’d be happy to share my tool with you. Just give me an address to send it to
peace
All you have to do is demonstrate that your method is more productive the other methods. That’s all.
Yes, because “off the top of your head” is as valuable as “I’ve spent a lifetime studying”.
I think you people think that reality is just like the bible. All you need to know you can obtain by reading a few pages. You simply don’t appreciate the depth of the knowledge you are missing. You don’t know what you don’t know.
This is easily demonstrated like so:
I’ve never given it much thought, but off the top of my head this whole bible/god/jesus thing is a bit silly and makes no sense. I’ve not read the bible nor any work by any scholars of the bible, but I’m sure it’s all wrong and nonsense.
You’d object to that, yet that’s exactly what you are doing here. You are claiming that, despite not knowing anything about the subject or thinking deeply about it you can say that existing definitions of species are vacuous and there is a better way, if only you’d consider the Platonic Form in the mind of God.
Don’t you see how silly that is? You know nothing and admit it, yet still know better then everyone else! The arrogance of religion right there!
Put it on pastebin, for the 50th time. http://pastebin.com/
I’ll happily put it up on a website just so we can destroy it.
Was it more efficiently, or was it metabolised at all? As you are a expert, you won’t have to look this one up will you?
Fifth is utterly confused about what evolution is.
I second the idea of you giving some examples of what you would consider an incorrect classification and demonstrate how your system improves on those errors.
If you can’t do that, well, I guess what a “true species” is will just have to remain a secret.
fifthmonarchyman,
As I explained in the OP, this is incorrect. Evolution does not turn on our definition of ‘species’. But a definition of species that did not accommodate it would be useless in an evolutionary setting. When you are asking ‘how did one species turn into another?’, you are unavoidably moving the conversation into an evolutionary setting. Therefore, you need to recognise what ‘species’ would mean in such a setting.
As has been pointed out, you simply want ‘species’ to be ‘that which only God can generate’.
fifthmonarchyman,
Absolutely and utterly useless. How many beetle species are there, according to your personal revelation?
So if we adopt the Platonic paradigm the species problem goes away? Sheesh.
That goes back to my question. Are Common and Spotted sandpipers separate or the same ‘Platonic’ species? Explain your reasoning. Why, when we attempt to deal with fine-grain issues, do we struggle to separate on a ‘Platonic’ paradigm? Is it because God isn’t revealing enough?
fifthmonarchyman,
Really? Let’s tell them, shall we?
However, taxonomists recognise that there is no such thing as a ‘true species’. That is why there is a species problem, because essentialism does not work. Because the real world of biology, of which you seem blissfully unaware, is blurry at the edges (exactly as one would expect if the current state had evolved).
And brain surgery is just a matter of making the approprate cuts. Nope, nothing hand-wavy about your definition, no sirree!
fifthmonarchyman,
Because we name them so! Lack of citrate growth is a diagnostic test for E coli, so if that were our ‘species criterion’, it would be speciation. Of course, you’d have a hard time persuading anyone to change the nomenclature on that basis alone, but there are examples elsewhere where similar amounts of distinction have led to renaming – particularly in disease-causing organisms. Pathological strains are in some sense a different ‘species’ from others with which they may or may not be lumped taxonomically – they have changed to exploit a particular ecological niche. Hard to tell whether God had the pathological or non-pathological forms separately in mind when he created them.
This is the trouble with any changing continuum. Letter by letter, stone by stone, there is never any reason to change names on a single step. But between more widely-separated points we are no longer looking at the fine scale. If we want to reclassify, we can do so. Naming things is done for our convenience.
Aren’t we all? It seems to be whatever you want it to be at any particular time.
No, we aren’t.
But thanks for admitting that you are confused about evolution.
Since species was invented as a concept back in the old days PROBABLY it was , like everything else back then, not done well or close to a accurate fact.
As i said species should be dismissed in biology.
For all people it should be obvious that biological change has happened and so from mechanisms and so these don’t have a objective to create species but only create new population for surviving in some niche. Including mankind.
So adding up attributes to form these species divisions is irrelevant to actual biological processes.
There is no reason for textbooks to say man is not divided into species using these invented attribute rules . If tigers and lions are species then so are people in thier ‘racial” groups.
It doesn’t work because its another incompetent error in studying biology.
There are no species but only segregated populations revealed by body attributes.
No thresholds are crossed that matter to biology.
Mung,
No, it’s inherited change in lineages and in populations, and the causes thereof. It is a convenient Creationist smokescreen to pretend that ‘nobody knows what evolution is’. In reality, it’s only the Creationists themselves that don’t.
The problem with the current definitions of species is not that individual classifications are incorrect it’s that we can’t say what a species is.
For the most part field biologists still classify using Phenetics at the species level. what would change is the work of Systematics determining the relationships between species. If we related species according to their shared characteristics instead of their evolutionary decent the tree of life would look a little different
Another place we would see the difference is in the field of deextinction, Scientists have been looking at combining the DNA of Woolly Mammoths with that of Asian elephants. The Platonic approach would say that if they created a creature with all the characteristics of the woolly mammoth it would be a woolly mammoth regardless of it’s parentage
peace
No because the color of the skin is not a defining characteristic of the human species anymore than the color of fur is a defining characteristic of canine species.
peace
exactly you are answering your own question and proving my point. We intuitively know that the efficient metabolizing of citrate is not enough of a change to declare a new species
peace
I am on a business trip right now I’ll look at it when I get back home. If the sign up is not a big hassle I’ll stick it in there. I plan on doing some more work on the website in the fall
peace
That would be cool. It’s a lot more fun when we can actually test a hypothesis
peace
not even wrong.
You go there. You copy the code, you paste it into the site. There is no sign up. There are only excuses.
Do “we”? Well, what change would you classify as a new species? Give an example!
For instance? All you are saying here is “if someone did some work to prove my point, my point would be proved”.
Unfortunately for you, the only person who is going to do that work is you.
But yes, let’s group everything by shared characteristics. Everything with four legs = same species?
That’s easy! Or did you mean something different?
fifthmonarchyman,
And that’s a problem only because species are largely a classificatory convenience, and nature is a little blurry at the boundary. You do all your biology from the comfort of your den. You seem unaware that natural groups are not neatly sorted into discrete bins. It’s exactly what evolution would predict, and what essentialists have to pretend does not exist.
Systematics has been used to determine the relationships between species for years. Once we started to get good protein and then DNA sequences, simple morphological characters started to take a back seat. Sequence data is nicely digital, and somewhat more objective, because one can look at indels, copy number, silent sites, structural conservation, karyotype and so on and so on, and not be so swayed by phenotype, and then apply this right across the tree of life. Morphology suffers somewhat from the lack of many universals.
To Creationists speciation is OK. Species are not immutable. Today’s species evolved from the originally created kinds.
It would be nice if evos actually learned what their opponents say.
fifthmonarchyman,
No, you are missing mine. For an equivalent amount of genetic and biochemical change, certain organisms have been separately classified, your intuition notwithstanding. Your intuition would be to keep them the same because they have only changed ‘a bit’. But scientists have chosen to adopt separate names in similar circumstances. It is our choice. A human names them, and then a Creationist insists evolution has not happened because a human still keeps the old name! As they would. Route 66 does not become Route 66.331 at any point. That would be silly. But many 2000-mile roads do change name on the way. But it’s the same road in the same sense Route 66 is.
Furthermore, citrate is just one change. Many others have taken place in the lineages. How many citrate-magnitude changes could take place before you accepted that there was a need for a new name? Two? Five? A million? Or would you not rename the species even if not a single fragment remained of the original genome?
Suppose one has two modern forms – call them ‘Zobras’ and ‘Yoks’. The Zobra genotype is ZZZZZZZZZZ, the Yok is YYYYYYYYYY. They are genetically unrelated (unlike real organisms). If a genotype changes from ZZZZZZZZZZ to ZZZZZZZZZY, ‘intuition’ would tell us that this is the same species, a Zobra. And the same intuition would apply at every step in the series
ZZZZZZZZYY
ZZZZZZZYYY
ZZZZZZYYYY
ZZZZZZYYYY
ZZYZZZYYYY
ZYYZZZYYYY
YYYZZZYYYY
YYYYZZYYYY
YYYYYZYYYY
YYYYYYYYYY
Intuition is clearly not much use here. It so happens in my hypothetical example the ancestral genome was ZZYZZZYYYY. If we’d lived then, we might have called it a Snurf. It certainly wasn’t a half-Zobra half-Yok – they did not even exist then.
The time axis is merely reversed above and below it. ZYYZZZYYYY and ZZZZZZYYYY would be declared mere variants around the ‘Snurf mean’. And yet by a succession of such no-changes changes, we end up with two modern species. How can that be? Well, it’s pretty obvious.
Coming along at the end of the time series, you’d insist that there are two essentialist species there that could not have an evolutionary relationship. But in the example, they do. The essentialist (in my example) would have been wrong. So what makes you so sure you are not that essentialist – the wrong one?
Frankie,
That’s only what some Creationists say.
I appear to be arguing, in fifthmonarchyman, with a species-immutablist, so it would be nice if you recognised that there is more than one Creationist viewpoint.