On the thread entitled “Species Kinds”, commenter phoodoo asks:
What’s the definition of a species?
A simple question but hard to answer. Talking of populations of interbreeding individuals immediately creates problems when looking at asexual organisms, especially the prokaryotes: bacteria and archaea. How to delineate a species temporally is also problematic. Allan Miller links to an excellent basic resource on defining a species and the Wikipedia entry does not shy away from the difficulties.
In case phoodoo thought his question was being ignored, I thought I’d open this thread to allow discussion without derailing the thread on “kinds”.
Astute readers will note that the Bristol Stool Chart attempts to dichotomise a continuum …
Do you think a diagnosis of diabetes or Aids or Cancer is arbitrary?
What about a declaration of a property as a wetland?
What about a declaration of death for that matter?
All of these things and many many others are determined by simply choosing a value in a range of values and declaring everything on one side category 1 and everything on the other category 2. Exactly the same thing as I’m proposing for species
Instead my definition being arbitrary it’s simply the common method we use to categorize every other thing we come across in our lives.
I think you should explain why it has been arbitrarily determined that species categorization should be different than every other categorization we do
peace
The policy decision will be made by a faceless bureaucrat under the (lack of) guidance from the endangered species act.
Because of an unworkable definition a unique population of organisms will loose protection and most likely become extinct.
That’s why this is a big deal
peace
It should work by you using your head and thinking for yourself about the implications of the current definition without having to be spoon-fed every little piece of information.
peace
Allan Miller,
LOL and an excellent point.
When you make an argument it’s up to you to support that argument. I know this may be a problematic concept for you, but there it is.
Nothing else reproduces.
Why are chemical elements determined differently than every other categorization that we do? Because they’re chemical elements, and they lend themselves to being categorized according to the number of protons in their nuclei (or number of electrons in an uncharged atom–same number).
Once they were determined rather more haphazardly and arbitrarily. But something like gold wasn’t really like something like brass, even if there are similarities between the two, as you can make brass by alloying zinc and copper, while gold–to the dismay of alchemists–couldn’t be synthesized. Still can’t be done by “chemical methods,” but what’s important to us now is why that is the case.
We make categories fairly arbitrarily, until we learn to do better. Species were once just organisms that seemed to be sufficiently different from other organisms to merit a different name. With bacteria and archaea, it’s still a lot like that. But over time it was learned that what we recognize as species of sexually-reproducing organisms are what normally interbreed in the wild, although since using that categorization it has been learned that some of what we thought were the same species actually aren’t because of breeding vocalizations or what-not.
It seems to me that issues of interbreeding always were more or less implicit in determination of species anyway. Darwin’s early conception of species was expressed thusly: “… I look at the term species as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other…” Later, he realized that this state of affairs apparently is typically the result of reproductive isolation, at least in sexually reproducing organisms (in his earlier conception, of course, certain hybrids could be species, while under later concepts they wouldn’t be–indeed, with current scientists recognizing that less-reproductively “fit” hybrids often are a kind of species “barrier” in the wild).
Categorization usually begins rather more arbitrarily, and ends rather more specifically. So it is with chemical elements, and with biological species in sexually reproducing organisms.
Glen Davidson
fifthmonarchyman,
The definition is no better nor worse than yours.
Finite resources must be targetted somehow. We can’t save every population of everything, much though we might like to. One of the threats to the coywolf is hybridisation with coyotes. You can’t do a huge amount about that in the wild, but it may readily lead to the loss of the ‘coywolf’, apart from repeat wolf-coyote hybridisation events. All this would, and should, inform decisions on the worthiness of large investment, when there are other populations that may benefit from efforts.
This is all rather reminiscent of Sal’s attempts to besmirch evilution by reference to medical research. Evolutionists are the enemies of (fairly) cuddly mammals.
fifthmonarchyman,
You defend your ideas of species by presenting what you claim (I’m not so sure) are arbitrary divisions of a continuum. But this isn’t appropriate for species, which are for the most part not arbitrary divisions. (Evolution, of course, assures there will be some such cases. But not so many.) I also note that you are defending your claims by saying that your claims are indefensible, an interesting tactic.
Bit of random serendipity. Came across this study on a population of mouflons entirely descended from an introduced pair. I see Dennis Venema has been refuting claims by William Lane Craig that this is evidence for historical Adam and Eve.
It seems to me that as more and more varieties of organism are sequenced, species and ring species and hybrids and varieties will fall out of the data, with quite a few fuzzy areas.
We have the same “problem” with human ethnicity. There are people who seem obviously to belong to a racial or national type, and there are hybrids.
But every living thing is a cousin of every other living thing. Some day, perhaps in the next 30 to 50 years, you will be able to find your exact degree of cousinship to every other person on earth. And every plant and critter will have its cousinship established with every other plant and critter.
I fail to see why there is anything to debate.
Not as many as you might suppose. There are no known cases of ring species. Hybrids between species are fairly rare compared to the number of species.
This is an excellent comment. It gets to the heart of the issue. It deserves much more than a drive by comment. I’m very busy this morning so I will address it as soon as I get a minute.
peace
My (broader) position is that species exist as objective discrete entities but thy don’t exist as physical things.
Instead of existing in the physical universe species exist in the world of the mind. This is the same place perfect circles and the concept of fourness exist.
I believe that the original sin of modern taxonomy is an attempt to treat the immaterial as if it were physical. I think this happened because of a philosophical stance that the immaterial is less than objective reality.
Since species don’t exist as physical things any attempt to mark their edges in the physical realm will be fraught with difficulty and bound to fail eventually.
That is the species problem in a nutshell.
The solution IMO is to abandon the strange “species as physical things” idea and embrace them as mental constructs that are never the less real.
Just like we do with every other kind of classification.
peace
ha. Your definition of species includes god. Just as I said.
fifthmonarchyman,
We? Who’s we?
us, The human race.
Every other classification we humans do involves “arbitrary” choice on our part.
For some reason when it comes to biology we expect the empirical to match the mental abstraction or we beleive that the abstraction does not exist at all.
We (humans) don’t do that with circles, or the color red, or the characteristic sharp, or the mathematical concept of (2) etc etc.
In each of those cases we must (decide) that what we see physically is equivalent to what we see in our minds eye.
Why should biological species be unique in this respect?
I think it’s because we know species are objectively real discrete things and some folks are philosophically adverse to the idea of the mental being objectively real.
peace
In whose mind is it objectively real?
Objective means it’s real everywhere, The same the ideal circle is real everywhere.
As a Christian I believe that all reality is grounded in God. Other folks might endeavor to ground it in other places.
peace
peace
A circle is not a species. There is one ideal circle. How many ideal species are there?
I get that. But if the concept of a particular species exists, that means that every single possible thing that exists of all combinations of all possible particles exists also as an ‘objectively real’ thing too? Otherwise who is thinking up these objective species? Presumably you think the circle exists at all because god created it? Did god therefore create all possible species too in ‘objective space’?
So what does it add to say that species exist as an objectively real thing if every other possible thing also does?
We certainly find pi in physical systems. I can believe in an ‘ideal circle’. I just can’t believe that the universe or god or whatever bothers to ‘imagine’ every possible species that might exist from every possible DNA sequence in every possible combination on every possible planet in every possible solar system etc etc.
There is no ‘grid’ on which discrete species sit FMM. Even if you had the resources of a deity, why bother?
Why not go all in, the physical universe exists in the same way and place as the perfect circle?
That’s fine.
My suggested definition for species works even if you refuse to entertain the idea that species are objectively real things. It just requires you to give up the idea that they are concrete physical things.
peace
Because the difference between the physical and the mental seems to be foundational to reality.
peace
It’s not that I refuse to entertain it. It’s that I don’t understand what it means. If you don’t want to explain your idea then fine.
Isn’t reality just an arbitrary category, too?
If by arbitrary you mean based on personal choice then yes.
We might disagree on who is doing the choosing but I think we would agree it always comes down to choice
peace
My idea is that it would be better not to deliminate species by reproductive compatibility. Because the current method is vague problematic and ultimately unworkable. It also could lead to things like the extinction of the red wolf.
What part of that do you need to be explained?
peace
The part where every possible species exists as an objective reality.
I think we have the intuition that species are objectively real. Whether this intuition correct is another question.
Darwin thought it was or he would not have worked so hard to explain their origin.
peace
Put words in his dead mouth if that suits your purposes.
Perhaps you could work up a concrete example of your plan for reclassifying organisms. My experience is what sounds simple in the abstract, isn’t always in the physical world.
I am sure biologists would welcome your input on how to improve the present system.
like this
http://literature.org/authors/darwin-charles/the-origin-of-species/
peace
Do you think that biologists feel that the present system needs improvement?
Once again for all practical purposes my system would not change how things are done at the species level. All that would change is the philosophical idea that species are bounded by reproductive compatibility.
quote:
Many systematists continue to use phenetic methods, particularly in addressing species-level questions. While a major goal of taxonomy remains describing the ‘tree of life’ – the evolutionary path connecting all species – in fieldwork one needs to be able to separate one taxon from another. Classifying diverse groups of closely related organisms that differ very subtly is difficult using a cladistic approach. Phenetics provides numerical tools for examining overall patterns of variation, allowing researchers to identify discrete groups that can be classified as species.
end quote:
from here
https://en.wikipedia.org/wiki/Phenetics
peace
This makes no sense to me unless you’re saying they all exist as concepts abstracted from the physical world and used to describe things in the real world. I would agree with that. “Species” is an abstract concept. It’s frequently a useful concept to use in referring to and recognizing certain clusters of similar individuals. But not all such clusters, and there’s your central problem. Since there are clusters of clusters of clusters, “species” can’t just refer to any cluster. It must refer to some particular sort of cluster. And that’s where reproductive isolation comes into it.
And I think that’s complete nonsense that you can’t possibly defend.
Nope, that isn’t it. “Four” doesn’t exist as a physical thing either, but attempts to count to four are usually successful. Same with species. Such difficulties as exist (and they are few relative to the number of species) result from evolution, particularly the gradual nature of speciation.
I would prefer to say that they are abstractions that usually fit the reality quite well. Like “four”.
As has been pointed out before, we don’t do that with every other kind of classification, with the classification of elements being a fine example, already mentioned several times.
I’m a biologist. Why not ask me? My answer is “no”.
Your system is so far so vague as to be unusable. Nobody can know whether it would change anything until you come up with real criteria and try to apply them. I suspect that your criteria, whatever they end up being, would not produce the same species we see today. There are examples of great phenotypic divergence with little genetic divergence, and vice versa. There are examples of great genetic and/or phenotypic variation within biological species, and examples of very little of either or both. The same applies to recency of ancestry and to ecological niche.
I don’t think that’s true. Sometimes degree of divergence, whether genetic or phenotypic, is used as a first pass to identify groups within traditional species that might warrant investigation regarding species status. But very few systematists would claim it to be anything else, and would still favor a species definition that wasn’t just “exceeds some particular amount of divergence”. Did I mention that I’m a systematist?
Sure. How have biologists resolved the question of whether species are objectively real? How can biologists even answer that question without going outside their role as biologists?
Most biologists would consider this a pointless philosophical question akin to angels and pinheads.
Have you read it yet?
Did species evolve or were they created FMM? Then you may have the right to talk about Darwin or not.
fifthmonarchyman,
I consider myself a member of the human race, and I don’t do anything like what you suggest. Where classification applies to physical things, it is those things that are being classified. Where one has a mental construct of ‘cups’, that is fully informed by experience of real cups. There will still be borderline cases, out there in the real world.
You wish to pretend that species are inherently dichotomisable. By ignoring the real things, and retreating into Mind.
As I’ve said before, you start from the position that most species-level organismal groups are neatly settable (due, if you did but know it, to reproductive isolation), and extend that to the unwarranted conclusion that all are. The premise does not lead to the conclusion.
fifthmonarchyman,
This again? Every conclusion you have come to is correct; the only reason anybody else should come to a different conclusion is because they have some kind of worldview commitment to avoiding Da Troof. Oi! WJM! Over here!
In order to count to 4 one must choose to consider groups of amorphous masses of molecules with no distinct boundaries to be distinct discrete individual entities separate from the molecules that surround them.
It’s all about arbitrary personal choice
please elaborate on how we can determine which element a particular atom is.
peace
1) These are not mutually exclusive categories.
2) species are concepts existing in the world of the mind so a better question would be “Do ideas evolve or are they formulated?”
peace
A long time ago. I can’t say it stuck with me to well.
fifthmonarchyman,
???
How do you determine that an object is borderline cup verses a full blown cup?
peace
How do you decide a particular molecule is part of a cup rather than part of the environment that the cup resides in?