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”.
That is only because you have an unworkable definition for species.
If you used something like my definition it would be no problem for a parent to be a different species than it’s child
peace
It’s not arbitrary but it is based on choice just as every other categorization we do as humans. I’m not fooling myself when I decide a particular object is a circle based on it’s similarity to a shape that exists in my mind.
The trick is to make our choice conform to the objective form of the thing
peace
no, My position that can better account for that fact than yours
I have no idea where this came from.
It’s me who is offering something new. I had no idea what esentialism was until a few years ago. I grew up with the same deficient concept of species that you have.
It’s me who is offering the new alternative I’m getting what seems like a reactionary defense from the folks on your side
peace
The evidence is all around you a female is not the same essence as a male. No one would ever say that they were the same
Despite the fact that every man has a mother.
You are unnecessarily restricting yourself. Essences are just the immaterial concepts that are manifested in a particular physical entity.
A cook does not have exactly the same essence as a candle stick maker
I simply disagree, individuals are individuals whether they are separated temporally or spacially.
Everywhere we look we see discrete individuals that we group and categorize. There are no fuzzy edges there are only individuals we can choose to group in different ways.
peace
You would if you knew the future and could see the rock dweller was the first of his kind and founder of a new species.
peace
So a convent of nuns is a different species than a gang of eunuchs?
peace
Do you imagine that you’re doing that with your definition, which I neglected to mention gives arbitrary weights to different characteristics?
Who told you that? And what does “for practical purposes” do for you there? According the the biological species concept, the lack of interbreeding has to be due to a genetic mechanism. According to the phylogenetic species concept, the populations have to have been geographically isolated long enough that each has at least one diagnosable difference from the other. I don’t think of any species concept that allows mere geographic separation to define species.
How? Oh, you don’t know, of course, any more than you can read the Bible intelligibly.
Not very quick, are you?
Wow, you really are an uneducated buffoon. I knew that claptrap about as soon as I learned actual science. It’s not new, which even you should be able to figure out.
Old stupid ideas that have long been discarded for being useless, and you’re thinking they’re bright shiny pennies.
You haven’t had an original idea in your life, have you?
Glen Davidson
No I’m trying to come up with an operational definition for species, one that better approximates what we actually do when we group organisms
Every choice is arbitrary to some extent. If it was not it would not be a choice.
peace
Do you need a nap?
peace
What do you mean by “we”? Certainly you aren’t referring to scientists, the people who actually do the grouping.
That’s nothing but wordplay. By “arbitrary” I mean there is no reason to prefer your choices over any other random assembly of criteria.
That is untrue I can defend my choices if asked.
Perhaps you would not be persuaded by my reasons but I am or I would not have made the choice.
sorry but that is incorrect. The scientists who do the grouping do it just like that.
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
OK, I’ll revise my understanding. Which came from being a birder, and noting that ornithologists were “splitters” and “lumpers”. The former tended to regard populations that didn’t breed as separate species, the latter regarded populations that were identical but simply geographically separated as one species. Over the years, some species were combined (crested and black-capped chickadees) while others were split (great-tailed and boat-tailed grackles) solely on the basis of geographical separation, and observing interbreeding (or not) where ranges overlapped.
The problem I have with “at least one diagnosable difference” is that even the most dedicated ornithologist couldn’t distinguish (diagnose) any difference, but the birds could do so consistently. Perhaps today geneticists can distinguish DNA variations that simply indicate different individuals, from DNA variations that are “diagnosable differences” between species. I wasn’t aware that the state of the art had reached that level of subtlety.
I disagree that ornithologists couldn’t notice differences. Song, for example, can play a major role. But so can morphological differences that are hard to see in the field. And DNA, of course. Of course great-tailed and boat-tailed grackles do overlap in distribution. I’m not familiar with “crested chickadees”, and they don’t seem to show up on the web either. Before my time?
In general, what you’re describing here is roughly a battle between fans of the biological species concept (lumpers) and phylogenetic species concept (splitters), though in the 19th Century there seems to have been an “I can describe the least little difference as a species” concept.
Genetic differences that distinguish phylogenetic species have to be fixed. Otherwise they wouldn’t be diagnosable.
Go for it.
Your approach isn’t phenetic, by the way. I’d describe it more as randomly eclectic, or perhaps as the Waring blender species concept.
You need to be more specific. Which of my choices do you disagree with and why?
perhaps, Except it’s not random and it’s elements are complementary.
Just as in orthodox taxonomy it has phenetic elements but it is supplemented with other measurable data to minimize the mistakes that might creep in if you rely on phenetics alone.
I find that triperspectival approaches do a better job of self correction than basing decisions on just one perspective.
peace
You have two of the three perspectives right there, all of them if you look at both mitochondrial and nuclear DNA.
It seems to me that we are not that far apart practically
All that separates us is your desire to hold on to the unworkable notion that reproductive compatibility is the determining factor in what makes a species
peace
That’s insulting. All that separates us is everything. Where applicable, reproductive isolation is a species definition. Everything I’ve mentioned is a criterion by which we can try to recognize reproductive isolation. You don’t really have a definition, so your criteria will not help you recognize anything. “Essence” is meaningless.
You need an actual species definition and a defense of that definition. Your decision to take the weighted average of four categories needs to be defended. Your decision on what weights to apply needs to be defended. Your decision to consider those categories, not other ones, needs to be defended. Your decision to set a particular threshold of weighted average as determining species status needs to be defended. And you need to stop playing word games.
Why do you think that reproductive compatibility is so important to the concept of species?
What is the compelling reason for you want to choose a squishy criteria like this to be the be all and end all?
peace
Why is mine not a definition? once we settle that we can work on your other questions one by one if need be
By the way I thank you for pointing out that I carelessly said relative “compared to organisms in other species” in my footnote when I should have simply said “relative to other organisms”.
Peace
What is your position on Platonic forms when not associated with biology? IOW Is the concept of a perfect circle meaningless in your opinion?
peace
Why do you think it’s squishy? It’s a good basis for definition because it what makes species separate. Species are separate gene pools, and reproductive isolation is what makes them that way over evolutionary time.
“Other organisms” doesn’t help. Isn’t every organism different from every other organism? So how can you decide that individual organisms aren’t species? The fact that degrees of divergence, however you measure it, are continuous makes your definition useless.
No, it’s a fine concept, an abstract concept that exists only as a concept. Calling concepts Platonic forms seems a useless reification to me. And nothing at all to do with biology. Again, species don’t have essences. They have populations of individuals that resemble each other in some ways and differ in others. No need to use a special term like “essence” to describe those resemblances.
peace
fifthmonarchyman,
It’s not just a matter of ‘definition’, it is a matter of biological reality. I don’t think you can even seriously conceive the situation you propose. You are just saying stuff ‘cos you like the sound of it.
fifthmonarchyman,
So you have a conception of an ideal elk in your mind? And you think you can observe a succession of generations and pinpoint the exact moment when a parent is of elk-essence and its offspring something else?
Where will it find a mate?
fifthmonarchyman,
So your methodology requires future vision. Very helpful, professor.
It seems that one can change the ‘essence’ of an organism by simply rescuing it from a rock.
There seems a poor grasp of the relevance of mating to the continuity of a lineage. It is not simply that reproductive compatibility is something we can observe and use as a diagnostic test, but, in obligately outcrossing lineages, it’s the only way the lineage survives. It is also the means by which characters are shared more widely, the primary cause of a significant number of individuals possessed of the same basic … ‘essence’, which we then recognise as conforming to a type, at least on the scale of our lifetimes.
If a new individual is of a new ‘essence’, its grandchildren are quarter-bred.
But they are not separate if reproductive compatibility is the criteria. horses and donkeys can mate so can wolves and coyotes so can Neanderthals and homo sapiens. In the plant world it’s even worse
On the other hand lots of organisms that aren’t reproductively compatible are clearly in the same species. For example post menopausal females are not a separate species.
some organisms are more different than others. That is why we look at relative difference
I think Ive already said the philosophical concept of genus and species can work all the way down to the individual if you want it to. It depends on how finely you want to chop it.
Again this is a feature and not a bug. It works with every other form of categorization we do.
for example
We can separate a set of objects into circles and non circles.
Then we can take the set of circles we have just compiled and increase the level of measurement and separate it into two sets the more circular and the less circular
We can do this repeatedly until we are left with one individual shape best exemplifies the ideal circle.
It works with any form we choose to look at
peace
yes, The same way one picks out a circle from a pile of objects of various shape
Reproductive compatibility is not an issue whatsoever in my approach. It’s just not about sex at all.
Organisms from different species often interbreed.
There is nothing hindering the founding member of a new species from breeding with members of other species.
peace
It only requires future vision to be 100 percent sure that your choice is the correct one. Since God has future vision his choice is the correct one.
We humans can approximate his choice by predicting the future. Prediction is one of the primary goals of science
peace
What exactly is it that makes reproductive compatibility a matter of “biological reality” in distinguishing species? Why did those pesky inter-species breeders not get the memo?
and what is it about biological categorization that makes it inherently different than any other categorization we do as humans?
peace
Why is it all about sex for you?
If an individual is a member of a new species it’s grandchildren are also members if they exemplify the form of that species.
This is true regardless of who they or their parents can have sex with.
peace
Go on then. Using your methodology predict something we currently don’t know.
Do you think taxonomy is a predictive enterprise?
peace
The inspiration for most of my ideas comes from the chapter on the principle of plenitude in Michael Denton’s Natures destiny.
Are any of you familiar with that chapter?
peace
It can certainly be used to predict things in conjunction with other data, yes!
For example:
http://www.int-res.com/abstracts/meps/v545/p239-249/
Presumably your methodology would have produced a different result?
why is that? Ive already said it’s practically the same as the one that John Harshman uses just with out the fuzzy sexual baggage
peace
Then why bother with your idea at all then? What does it add?
OMagain:
It brings God and his “future vision” into the picture.
It’s like fifth is obsessed, or something.
Paleontologists will argue passionately about whether a particular fossil is, say, Australopithecus or Homo. But any evolutionist knows there must have existed individuals who were exactly intermediate. It’s essentialist folly to insist on the necessity of shoehorning your fossil into one genus or the other. There never was an Australopithecus mother who gave birth to a Homo child, for every child ever born belonged to the same species as its mother. The whole system of labelling species with discontinuous names is geared to a time slice, the present, in which ancestors have been conveniently expunged from our awareness (and “ring species” tactfully ignored). If by some miracle every ancestor were preserved as a fossil, discontinuous naming would be impossible. Creationists are misguidedly fond of citing “gaps” as embarrassing for evolutionists, but gaps are a fortuitous boon for taxonomists who, with good reason, want to give species discrete names. Quarrelling about whether a fossil is “really” Australopithecus or Homo is like quarrelling over whether George should be called “tall”. He’s five foot ten, doesn’t that tell you what you need to know?
Richard Dawkins here.
1)It eliminates the species problem
2) it makes taxonomy intuitively just like any other categorization that we do.
That reminds me, My method is predictive in that if you know 2 of the perspectives you can predict the third
peace
if that is true then the organism prior to that point is Australopithecus the one after it is homo
species problem solved.
Nothing difficult here unless you want to cling to the philosophical notion of a grand continuum of life.
Why do you find that belief so appealing that you would cling to it even when it is so prone to difficulty?
That depends on whether you choose to call five foot ten tall or not
I wouldn’t but Tom Cruse might 😉
peace
peace
It’s demonstrable. That you refuse to see it is your loss.
What? Please demonstrate it then ?
here is what you are up against.
Humans see the world as consisting of discrete things. Tells us how we are demonstrably mistaken
peace
fifthmonarchyman,
From your link:
The “problem” is not a problem. 🙂
Reproductive isolation need not be complete. As long as there’s enough that the gene pools don’t merge, we consider them separate species. If that’s what you meant by “squishy”, then sure, evolution makes for a certain percentage of ambiguous cases. But even plants have separate species determinable by the biological species concept.
Here you make the common mistake of confusing individuals with populations. Please don’t.
Again with the “we”. Trying to gain vicarious legitimacy? You have no defensible reason to locate a line between clusters of individuals, calling some the same species and others different species. I do.
Word play again. You are confounding two different meanings of species and genus. The biological meaning only is relevant here. Organisms aren’t circles.
Dawkins:
fifth:
Come on, fifth. Even you should be able to see the problem with that reasoning.
1. Consider a lineage leading from species A to species B.
2. Now consider the same lineage leading from species A through species C to species B.
3. Apply your fallacious reasoning to both cases.
4. Observe the contradictions.
“Species problem solved”, my ass.
Start here: http://darwin-online.org.uk/Variorum/1859/1859-1-dns.html
And we can take it from there.
What are you saying fmm? That things did not evolve over time, that there is not a continuum of life embodied in many consiliant lives of evidence?
Were species explicitly created with no predecessors then? When? 4000 years ago?
What should we replace the idea that there is a grant continuum of life with?