Tautology and Natural Selection

quote:

---

Fitness & reproductive success are one & the same, they are equal, neither is measured by the other. I boobed when I said (words to the effect of) fitness is a measure of rs, poor English on my part.

---

I dont' see how you can say that. 'Reproductive success of the fittest' seems like a valid description of natural selection. If fittest is reproductive success, then the phrase is a tautology. Shouldn't fitness be 'best engineered for reproductive success'?JustinC

Hi Justin
I see that you and John went through most of the points in my post so I will pick up from where you two left off.

quote:

---

Whose arguing tautologies are fallacious? I'm not. But tautologies do not make predictions and are not scientific statements. I'm saying if "survival of the fittest" is defined by a post hoc analysis, you get "survivors survive". That isn't a scientific statement, it's an empty statement. Saying "Survivors survive" doesn't give any clue as to the direction of evolution. The statement would be true under any scenerio, i.e. if all organisms survive randomly.

---

The problem is that it is an observation i.e. that some individuals or variants produce more offsrpring than others. The traits that allow this to occur confer a fitness advantage to the individual bearing them. The science is trying to identify the individuals in a population that contribute the most to the next generation and then determine which traits are providing the advantage in that environment. One can of course make predictions that need not be so drastic as dropping a fish in a desert and seeing if it reproduces more or less than a gila monster. Here is an experiment in survivial of the fittest that I do almost every day...I often clone PCR products into a vector that then gets electroporated in bacteria competent to recieve said vector. The vector includes the gene for ampicilin resistance. Only a tiny fraction of the bacteria will take up the vector of the millions of bacteria electroporated. The selective force of their environment come when I plate them on an agar plate consisting of everything that makes bacteria grow happily plus a crap load of ampicilin...of the millions of bacteria that I plate, who has the selective advantage? what do you think I will see the next day on my plate? Will all the bacteria I plated grow equally?...the answer is that only the bacteria that took up my vector grow and form colonies on the plate because they can survive the antibiotic...survival of the fitest. There are natural examples of this as well rather than this experiment.

quote:

---

Also, in that case where you live in a complete darkness, you are just wasting resources developing organs which have no use. You have to have a reference to the environment.

---

This is again why I don't like even using the word engineering in describing nature...all biological life wastes huge amounts of energy on all sorts of things that are unecessary..but merely get the job done. Oxidative phosphorylation is extremely sloppy i.e. we only use a small fraction of the potential energy from the food we eat. Most genomes are chock full of DNA that are relic retrotransposons..while some are biologically important, many are inert..yet they get copied (again a huge waste of energy) in every cell division...if engineering principles were used to guide (since I guess you are ultimately trying to argue intelligent design here) not a single life form would pass the muster regarding optimized design principles....what you see in nature is what left more offspring behind than something else for multiple reason from selection, to catastrophic climate change, to just plain random chance...much like my amp resistant bacteria and the catastrophic climate change of mean Mammuthus plating them on nasty antibiotic containing food.

That bit was toward the end of my post -- after I said
'If you describe fitness in some survival oriented way'If you don't ... then I agree with you.

quote:

---

fitness is not a cause.

---

I was commenting on how one defines 'fitness'. Fitness is
not a cause if it is defined as BEING reproductive success
(as mark24 has explained it).IFF fitness is defined in survival terms only, then it can
be a cause of reproductive success (if one is more fit the
one leaves more offspring -- which is how I have always
interpreted natural selection btw).It is never (in either case) approriate to say that reproductive
success causes fitness ... if they are the same thing one cannot
cause the other, and I do not know of another definition of
fitness that would allow it to be caused by reproductive success.Blame Darwin, he's the one who came up with these dangerous
notions ... it's not us laymen's fault that biologists have
redefined everything since then

You were okay up to here, I think. As Mammuthus pointed out, the engineering analogy falls flat as the only way we can call an organism "fit" is by the post hoc analysis: if it survived, it was fit enough to do so. Merely an observation, and somewhat trivial to boot. In addition, the idea of "best engineered" doesn't work when you take into consideration evolutionary anachronisms like Persea (avocado), Gleditsia triacanthos (honey locust), etc. They reproduce in the wild, more or less, but do so veeerry inefficiently, since their reproductive strategies rely on seed dispersal by critters that have been extinct for 10,000 years. They are "fit" in the sense that they have persisted as a lineage even in the absence of a well-engineered reproductive strategy. They are "good enough" (barely), but not necessarily fitter than other plants in their various habitats.

quote:

---

As Mammuthus pointed out, the engineering analogy falls flat as the only way we can call an organism "fit" is by the post hoc analysis: if it survived, it was fit enough to do so.

---

The engineering assumption would only work, in other words, if we knew absolutely everything relevant about the fitness landscape, including freak contingencies. How many of us wouldn't have had our money on the dinosaurs as trophy winners? Not even the most stringent engineering analysis could have made us aware of the comet hurtling toward Earth that would change the fitness landscape so drastically.------------------
Quien busca, halla

I don't disagree at all inre fitness landscapes.You raise an interesting question, however. I wonder if it is really necessary to take mass extinction events into consideration when discussing population or species-level adaptive fitness? I don't mean source-sink dynamics (the "christmas lights" phenomena), or Vrba's turnover pulse species exchange (which is regional). These more-or-less local events would/could have differential survival based on phenotype etc. I mean the really BIG die-offs like the K/T extinction or the P/T extinction event which literally rewrite the evolutionary script for a substantial fraction of the planet. Heck, the P/T extinction nearly cancelled the entire experiment. I'm not clear that any fitness measure at all would be relevant to this level of event. Meaning I'm not sure it would be necessary to take them into consideration for a discussion of relative or absolute fitness or adaptation.Mammuthus is our resident extinction expert (although specializing in Late Pleistocene). Maybe he's got an idea or two?BTW: You're right, paying off the margin call for the damn dinosaurs was the pits...

If you are talking about fitness in any sense or
definition -- mass extinction events aren't relevant.In another topic I referred to the inapproriateness of
looking at endangered species from an evolutionary/natural selection
PoV unless some were bullet-proof ....That said one has to wonder if there are features of
extant critters that would allow them to survive in preference
to other species in different global catastrophies --
like ants and cockroaches surviving nuclear blasts or some such.Were the asteroid impact survivors survivors due to pure chance
or because they were fitter with respect to the radically
modified environment?[Added by edit:: I ... I think I might have changed my mind
halfway through that post -- wow a transitional!!! [This message has been edited by Peter, 07-28-2003]

quote:

---

Were the asteroid impact survivors survivors due to pure chance
or because they were fitter with respect to the radically
modified environment?

---

Completely rhetorical question, and rightfully so. As you have mentioned before, the ancestors of modern birds survived the extinction of the rest of their cousin species.Granted, this aspect of the dino fitness landscape would have been so difficult to predict at the time that we would have been justified in considering such a drastic change highly improbable. And as Bill Dembski will tell you, highly improbable events never happen.I realize Gould felt that mass extinctions and other contingencies were weaknesses in the Darwinian framework, but I fail to see how dramatic changes in the fitness landscape somehow invalidate the concept of natural selection.------------------
Quien busca, halla

I just inject 3 (perhaps vague) comments:1) The "survival of the fitest" phrase is widely considered to be merely an approximation - not to be taked too literally.2) It has been vaguely touched upon, but seemingly not explicitly stated - The "survival of the fitest" is a matter of statistical probability - Not all the "most fit" survive to reproduce, and some of the "less fit" do survive to reproduce.3) Concerning the asteroid impact - My impression of things is that the environment of the time was already undergoing a radical, if not as sudden of a change as an asteroid impact. A major extinction event was happening prior to the asteroid showing up. Perhaps a worthy topic would be "How significant was the asteroid impact, in the K-T extinction event?". But I'm not going to start the topic.Moose------------------
Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment.
My big page of Creation/Evolution Links

quote:

---

The problem is that it is an observation i.e. that some individuals or variants produce more offsrpring than others. The traits that allow this to occur confer a fitness advantage to the individual bearing them. The science is trying to identify the individuals in a population that contribute the most to the next generation and then determine which traits are providing the advantage in that environment.

---

Agreed.

quote:

---

One can of course make predictions that need not be so drastic as dropping a fish in a desert and seeing if it reproduces more or less than a gila monster. Here is an experiment in survivial of the fittest that I do almost every day...I often clone PCR products into a vector that then gets electroporated in bacteria competent to recieve said vector. The vector includes the gene for ampicilin resistance. Only a tiny fraction of the bacteria will take up the vector of the millions of bacteria electroporated. The selective force of their environment come when I plate them on an agar plate consisting of everything that makes bacteria grow happily plus a crap load of ampicilin...of the millions of bacteria that I plate, who has the selective advantage? what do you think I will see the next day on my plate? Will all the bacteria I plated grow equally?...the answer is that only the bacteria that took up my vector grow and form colonies on the plate because they can survive the antibiotic...survival of the fitest. There are natural examples of this as well rather than this experiment.

---

Yes, i'm not arguing that survival of the fittest doesn't happen. I've actually done that experiment in my Biology lab (although we didn't prepare the vectors ourselves). You can make the prediction before hand because you are figuring out what is best engineered for reproductive success (ceteris paribus) in the ampicilin agar environment. There are features in environments that a priori are better for reproductive success. The same thing goes for any other object with a function. If one thinks that "survival of the fittest" is tautologous and unuseful, they'll have to concede that all of engineering is the same way.

quote:

---

This is again why I don't like even using the word engineering in describing nature...all biological life wastes huge amounts of energy on all sorts of things that are unecessary..but merely get the job done. Oxidative phosphorylation is extremely sloppy i.e. we only use a small fraction of the potential energy from the food we eat. Most genomes are chock full of DNA that are relic retrotransposons..while some are biologically important, many are inert..yet they get copied (again a huge waste of energy) in every cell division...if engineering principles were used to guide (since I guess you are ultimately trying to argue intelligent design here) not a single life form would pass the muster regarding optimized design principles....

---

If I was arguing optimally engineered for energy utilization, then I would see your point. But I'm just arguing better engineered for reproductive success.And let me clear things up, I am not arguing for intelligent design.
I've been reading books on evolution since I was 12, I am an Evolutionary Biology major, and I am an evolutionist/atheist.I understand natural selection, i'm just trying to figure out a better way to articulate it.

quote:

---

what you see in nature is what left more offspring behind than something else for multiple reason from selection, to catastrophic climate change, to just plain random chance...much like my amp resistant bacteria and the catastrophic climate change of mean Mammuthus plating them on nasty antibiotic containing food.

---

Agreed.EDIT: Has anyone read Elliot Sober's "The Nature of Selection"?[This message has been edited by JustinCy, 07-28-2003]

quote:

---

You were okay up to here, I think. As Mammuthus pointed out, the engineering analogy falls flat as the only way we can call an organism "fit" is by the post hoc analysis: if it survived, it was fit enough to do so. Merely an observation, and somewhat trivial to boot.

---

I still wouldn't say "only by the post hoc analysis." In Mammuthus E.coli example, you didn't need a post hoc analysis. I'd say its analogous to testing wings in a wind tunnel. You can figure out before hand what will be a good wing for lift, but the best way and most pragmatic way is to just place it in the tunnel and see how it performs.

quote:

---

In addition, the idea of "best engineered" doesn't work when you take into consideration evolutionary anachronisms like Persea (avocado), Gleditsia triacanthos (honey locust), etc. They reproduce in the wild, more or less, but do so veeerry inefficiently, since their reproductive strategies rely on seed dispersal by critters that have been extinct for 10,000 years. They are "fit" in the sense that they have persisted as a lineage even in the absence of a well-engineered reproductive strategy. They are "good enough" (barely), but not necessarily fitter than other plants in their various habitats.

---

If a mutation arises which increases reproductive success in those organisms, then the mutants would certainly overtake them as they are today. It manifestly hasn't. Them being "good enough" is consistent. What are they good enough for? Reproductive success. So they are better than all their ancestors for reproductive success. Why does changing the curvature of wing increase it's lift? An explanation is given about pressures and forces. And then a person would ask why again? And you'd be forced to say, "because that increases lift". "Increased lift by the best engineered wing" seems like a good description. It just seems like all things with a function can be described as tautologous.Any thoughts?JustinC[This message has been edited by JustinCy, 07-28-2003]

Hi Justin. This is a neat discussion, btw. I agree in these cases. However, the critical distinction here is that with experiments such as you reference, you know every aspect of the fitness landscape - in fact, you control it - in advance so it's fairly easy to make a reasonable prediction as to potential outcomes. When examining a population in locus, however, the only way you can determined fitness is by a detailed examination of the fitness landscape in which the population resides. An a posteriori analysis. Sometimes you can get enough of the natural history of the organism to state that a given characteristic or suite of characteristics provides "better" fitness. Most of the time, however, you have to extrapolate from questions such as why this organism rather than that one occupies a given niche. IOW, what traits are possessed that makes the organism "fitter".What the E. coli experiments and others of the same type provide is unequivocal (well, to anyone but a creationist) evidence of the creative power of natural selection acting on statistical variation within a population. As to the wind tunnel, of course you can occasionally take a given design and determine whether it is "better engineered" than another. However, translating that better wing shape into population mean fitness - or even relative fitness - is misleading without, as Mr. Hambre pointed out, taking into consideration the rest of the fitness landscape.There are documented cases where certain obvious traits in natural populations have been isolated to the point where we can say "this trait increases the statistical probability of survival and/or reproduction in this organism". I'm thinking primarily of beak size in the Grants' Geospiza studies where .5 mm difference spelled a statistical difference in survival (!!) and the one with the guppies (I'll have to look up the specifics, I don't have my books here at the office) where variation in spot patterns, color, and size spelled the difference in predator-selected survival. There were fairly significant and key (read easily identifiable) selective pressures on both of these populations that would tend to swamp or overwhelm potentially countervailing or reinforcing selective pressures. However, these are relatively rare occurances and it has been extraordinarily difficult to document many other examples.Then again, evolutionary ecology is still a very young science. I have high hopes that much refinement and many more examples will be forthcoming - to the point where we may be able to get an accurate picture of what's going on. Hypothetically speaking, that would be true. However, I mentioned specific organisms which are "holding on" with significantly reduced ranges (in the wild), which are not occupying many potential habitats, and/or which rely on secondary or even tertiary dispersers for bare replacement. There's a whole flipping list of plants - especially in the neotropics - which aren't "better than all their ancestors". These guys are evolutionary relicts - fading memories of the distant past (forgive the lyricism). If I might speculate for a moment, I would say that these organisms are living examples of species exchange - caught in the act, as it were. Further, I'd speculate that - absent your hypothetical mutation that allows adaptation - these species would be doomed in the wild if left to their own devices. Or they'll end up like Wollemia nobilis - a microscopic remnant of a once widely spread species hidden away in some remote, inaccessible habitat where they cling to a precarious existence in the absence of competition from other, hardier and more adaptable organisms.These organisms aren't "fittest" by any stretch. They're sitting way down the slopes of their particular adaptive peak. Or rather, they've passed the peak and are way down the other side. Again, taking the wing out of its context, it really does make it a tautology. Most definitions are. However, just because a particular wing shape gives it better lift than some other similar shape doesn't translate into fitness for the organism possessing that wing shape. Better lift might be counterproductive in a case where flying increases the chances of predation or being blown out to see. I understand what you're trying to say. I'm merely attempting to point out that the "best engineered" concept is misleading without taking into consideration the remainder of the adaptive pressures operating on the organism/population.

Hi Justin,

quote:

---

Yes, i'm not arguing that survival of the fittest doesn't happen. I've actually done that experiment in my Biology lab (although we didn't prepare the vectors ourselves). You can make the prediction before hand because you are figuring out what is best engineered for reproductive success (ceteris paribus) in the ampicilin agar environment. There are features in environments that a priori are better for reproductive success. The same thing goes for any other object with a function. If one thinks that "survival of the fittest" is tautologous and unuseful, they'll have to concede that all of engineering is the same way.

---

Actually this is not completely true. You can stack the odds in favor of a desired outcome, however, perhaps a bacteria that deletes part of your insert has a fitness advantage or knocks everything out except the promoter and the amp resistance gene has an advantage...then you end up with an unexpected and undesireable result. This actually happens in most of these experiments i.e. there is a substantial fraction of surviving bacteria that do not have what you wanted in or selected for. This will happen under almost any circumstances i.e. fairly homogeneous populations can produce novel variants as well that fall somewhere else in the fitness landscape, better, worse, the same...I would not concede that surival of the fittest is unuseful only that as moose pointed out, due to chance events i.e. boloid collisions etc. less fit organisms can survive and reproduce. Again, it is a probability. The observations is that some alleles, variants, are more predominant than others...that is something you can go out and test. The explanation is that said variants have come to predominate by having more offspring i.e. higher fitness.....where survival of the fittest goes a bit astray is that it is a bit all or nothing...a certain trait can be at a high frequency without driving all other variants to extinction. The tough part is to figure out why certain variants predominate in natural populations. We can do ham fisted mimicry of what occurs naturally over short time scales i.e. dog breeding, plant breeding etc...but what you should keep in mind is on the way to making fifi the chihuahua there were a lot of unexpected variants that cropped up along the way...in addition, artificial selection is not an excersise in survival of the fitest as it is actually survival of an aesthetic by human interference...I really doubt that fifi would have much of a competetive advantage in hunting when forced to hunt for food in wolf territory.

quote:

---

If I was arguing optimally engineered for energy utilization, then I would see your point. But I'm just arguing better engineered for reproductive success.
And let me clear things up, I am not arguing for intelligent design.
I've been reading books on evolution since I was 12, I am an Evolutionary Biology major, and I am an evolutionist/atheist.

​

I understand natural selection, i'm just trying to figure out a better way to articulate it.

---

My problem with using the term engineering is that implies intent i.e. purpose. If you just have an increase in representation of variants that produce more offspring regardless of whether it makes them better or worse from an engineering perpective it is the opposite of engineering. Remember, you can have variants arise that say see worse than other variants but are so fecund that they come to dominate..from an engineering perspective this is crazy..but from natures point of view it makes sense.I was not trying to accuse you of being an intelligent design proponent or assign to you a religious ideology. I am just trying to argue that to include concepts such as enhanced engineering, engineering for reproduction goes in a direction that leads to more confusion than less i.e. organisms are designed and it is self evident which is the ID line...talk about useless concepts..they can't even propose a testable hypothesis. Engineering sounds like design.cheers,
M

quote:

---

I agree in these cases. However, the critical distinction here is that with experiments such as you reference, you know every aspect of the fitness landscape - in fact, you control it - in advance so it's fairly easy to make a reasonable prediction as to potential outcomes. When examining a population in locus, however, the only way you can determined fitness is by a detailed examination of the fitness landscape in which the population resides. An a posteriori analysis. Sometimes you can get enough of the natural history of the organism to state that a given characteristic or suite of characteristics provides "better" fitness. Most of the time, however, you have to extrapolate from questions such as why this organism rather than that one occupies a given niche. IOW, what traits are possessed that makes the organism "fitter".

---

I agree with all of that....I think. Do you think I don't? I'm just wondering so I can articulate what I am saying better in the future.

quote:

---

What the E. coli experiments and others of the same type provide is unequivocal (well, to anyone but a creationist) evidence of the creative power of natural selection acting on statistical variation within a population. As to the wind tunnel, of course you can occasionally take a given design and determine whether it is "better engineered" than another. However, translating that better wing shape into population mean fitness - or even relative fitness - is misleading without, as Mr. Hambre pointed out, taking into consideration the rest of the fitness landscape.

---

I'm not using the wing in terms of how it functions on an organism and the fitness it will induce. I'll explain below.

quote:

---

There are documented cases where certain obvious traits in natural populations have been isolated to the point where we can say "this trait increases the statistical probability of survival and/or reproduction in this organism". I'm thinking primarily of beak size in the Grants' Geospiza studies where .5 mm difference spelled a statistical difference in survival (!!) and the one with the guppies (I'll have to look up the specifics, I don't have my books here at the office) where variation in spot patterns, color, and size spelled the difference in predator-selected survival. There were fairly significant and key (read easily identifiable) selective pressures on both of these populations that would tend to swamp or overwhelm potentially countervailing or reinforcing selective pressures. However, these are relatively rare occurances and it has been extraordinarily difficult to document many other examples.

---

Agreed.

quote:

---

Then again, evolutionary ecology is still a very young science. I have high hopes that much refinement and many more examples will be forthcoming - to the point where we may be able to get an accurate picture of what's going on.

---

Just out of curiousity, is anyone here an evolutionary biologist or know anybody in the field? I'm majoring in Biology right now, but I want to specifically go into Evolutionary Biology, and even more specifically Paleoanthropology. I'm going to be a sophomore, so either way classes for my specific major haven't been taken yet.

quote:

---

Hypothetically speaking, that would be true. However, I mentioned specific organisms which are "holding on" with significantly reduced ranges (in the wild), which are not occupying many potential habitats, and/or which rely on secondary or even tertiary dispersers for bare replacement. There's a whole flipping list of plants - especially in the neotropics - which aren't "better than all their ancestors".

---

Maybe I wasn't specific enough. I mean better than their immediate ancestors, again barring genetic drift.

quote:

---

These guys are evolutionary relicts - fading memories of the distant past (forgive the lyricism). If I might speculate for a moment, I would say that these organisms are living examples of species exchange - caught in the act, as it were. Further, I'd speculate that - absent your hypothetical mutation that allows adaptation - these species would be doomed in the wild if left to their own devices. Or they'll end up like Wollemia nobilis - a microscopic remnant of a once widely spread species hidden away in some remote, inaccessible habitat where they cling to a precarious existence in the absence of competition from other, hardier and more adaptable organisms.

---

I'm still not sure how this is objectionable to my statements. They'd have to be better engineered for reproductive success than their immediate ancestors for them to be here at all, even if they are now in a state of decline due to environmental changes or because of variant populations.Out of curiosity, what do you mean by species exchange? Do you mean being replaced by a closely related species that they share a common ancestor with?

quote:

---

Again, taking the wing out of its context, it really does make it a tautology. Most definitions are. However, just because a particular wing shape gives it better lift than some other similar shape doesn't translate into fitness for the organism possessing that wing shape. Better lift might be counterproductive in a case where flying increases the chances of predation or being blown out to see. I understand what you're trying to say. I'm merely attempting to point out that the "best engineered" concept is misleading without taking into consideration the remainder of the adaptive pressures operating on the organism/population.

---

I wasn't referring to the wing in context of an organism, I was actually thinking about jetplanes when I wrote it. I was analogizing the wing situation with the organism situation, i.e. wing=organism, lift=reproductive success, and air=environment. Wings lift and organisms reproduce. So you'd factor in everything that effects lifting or reproduction. In the case of reproduction, wings lift may or may not affect reproduction; that wasn't my point though.[This message has been edited by JustinCy, 07-29-2003]