the 1998 paper reports on experiments with predationAn unidentified microflagellate specie (4-12 [mico]m) and Chlorella Prenodosa (2-5 [micro]m) were grown at 25 C in mixed-species chemostats with constant light and sterile, inorganic medium flow. The flagellate readily consumed the algae and grew rapidly (doubling time ca. 6 h). Size distributions of both species are shown in the Figure (area = biovolume). After an initial oscillation (curves 1,2), the system apparently stabilized with both species coexisting. The algal population now consisted of clusters of 4 to tens of cells that were immune to predation by the flagellate (curve 3). The mean cluster size then steadily decreased (curve 4) and stabilized at 4-8 cells (curve 5). These, and other, observations support the hypothesis: (1) a multicellular algal form was selected as a response to predation pressures, (2) a minimum cluster size was selected due to nutrient competition (large clusters have a smaller surface area per unite biomass) and (3) genetic, morphological, and structural diversity of the system increased as a response to predation. Flagellate predation influences both the genetics and the dynamics of microalgal population."
The article showed how when a common uni-celllular alga "Chlorella vulgaris" was exposed to a predator "Ochromonas vellesiaca", a phagotrophic flagellate, within 100 generations or so, a multicellular (colonial) specie arose . The results were discussed in a 2000 TalkOrigins Post of the Month by Adam Noel Harris and in TalkOrigin's Index to Creationist Claims CB904 In other words, the innovsative step from single to multi-cellular may well have taken place under selective pressures of predation. The work by Boraas shows that even accidents such as allowing predators iside chemostats can lead through hard work to fascinating new scientific findings and insights. The authors mention that other than in rare instances, the Chlorella culture had always exhibitied its normal unicellular morphology over a timeframe of 2 decades. When the predator was introduced, predictably the prey density declined and the predator density increased. When the predators started to run out of food, they started to decline and the reduction in predation led to a recovery of the Chlorella population (this is a classical pre-predator interaction). During the recovery phase, it was noticed that in addition to unicellular forms, there now existed colonial forms with the numbers of cells ranging from four to hundreds. Eventually the system entered a steady state with the Chlorella population consisting of colonies of 8 cells. These colonies were not only stable but also self-replicating The authors conclude that the muli-cellular form is a rare mutation which was selected by predation and thus 'amplified'. The authors also discuss the issue of induction, namely that the flagellates released a substance that caused colony formation. Given that it took almost 20 generations before colonies became apparant, the authors reject this alternative. Additionally, multicellular colonies were maintained even in low density cultures and finally, when the colonies are allowed to reproduce by themselves, they reproduce as colonies not single cells. The authors finally show how these experiments support a thesis by Stanley that multicellular life arose late into the pre-Cambrian under selective pressure of predation. Was the Cambrian explosion in other words, an arms race between prey and predator? That under selective pressure, mulicellular colonies arose, shows how the simple processes of variation and selection can surely explain innovation and increase in complexity. Stanley, S.M. (1973) An ecological theory for the sudden origin of multicellular life in the Late Precambrian PNAS 70, 1486-1489.Summary Predation was a powerful selective force promoting increased morphological complexity in a unicellular prey held in constant environmental conditions. The green alga, Chlorella vulgaris, is a well-studied eukaryote, which has retained its normal unicellular form in cultures in our laboratories for thousands of generations. For the experiments reported here, steady-state unicellular C. vulgaris continuous cultures were inoculated with the predator Ochromonas vallescia, a phagotrophic flagellated protist (`flagellate'). Within less than 100 generations of the prey, a multicellular Chlorella growth form became dominant in the culture (subsequently repeated in other cultures). The prey Chlorella first formed globose clusters of tens to hundreds of cells. After about 10-20 generations in the presence of the phagotroph, eight-celled colonies predominated. These colonies retained the eight-celled form indefinitely in continuous culture and when plated onto agar. These self-replicating, stable colonies were virtually immune to predation by the flagellate, but small enough that each Chlorella cell was exposed directly to the nutrient medium.
According to modern ecological theory, high diversity at any trophic level of a community is possible only under the influence of cropping. Until herbivores evolved, single-celled algae of the Precambrian were resource-limited, and a small number of species saturated aquatic environments. In the near-absence of vacant niches, life diversified slowly. Because the changes required to produce the first algae-eating heterotrophs were therefore delayed, the entire system was self-limiting. When the ``heterotroph barrier'' was finally crossed in the late Precambrian, herbivorous and carnivorous protists arose almost simultaneously, for no major biological differences separate the two groups. These events automatically triggered the formation of a series of self-propagating feedback systems of diversification between adjacent trophic levels. Comparable systems arose among multicellular groups, which radiated rapidly from the newly diversifying protist taxa. The sudden proliferation of complex food webs formed by taxa invading previously vacant adaptive zones produced an explosive diversification of life over a period of a few tens of millions of years. The rapid appearance of skeletons in various groups, though of special geological importance, was no more dramatic than other aspects of the radiation. The overall rate of diversification was comparable to rates for less-extensive adaptive radiations of the Phanerozoic.
256 Comments
Henry J · 13 February 2006
Re "Was the Cambrian explosion in other words, an arms race between prey and predator?"
Fascinating!
qetzal · 13 February 2006
Great post and great topic!
Question - anyone know any good research on why multicellular organisms are almost all eukaryotic?
PvM · 13 February 2006
PvM · 13 February 2006
Using these relatively simple organisms, we can 're-create' plausible pathways for the evolution of multi-cellularity, the evolution of sex and the evolution of diversification. Not bad
Bruce Thompson GQ · 13 February 2006
This would appear to be analogous to recent events at
Uncommonly Decent. The Blog has become multi-cellular but in addition displays cellular specializations. The appointment of a Blog Czar with online banning and censorship powers indicates an additional level of complexity and cellular specialization. While PT is also characterized by multiple contributors and can be considered multi-cellular the cellular specialization found at UD is lacking and suggests that predation (selection) is much stronger on that population and recent events such as the Kitzmiller decision support that conclusion. The resultant population stability observed in newly evolved multi-cellular Chlorella algae suggests that ID and belief based notions about biological complexity will continue to survive. Since it is hypothesized that minimum cluster size is dependent upon nutrient access, the best method to combat large clusters is better science education reducing available nutrients.
Delta Pi Gamma (Scientia et Fermentum)
BlastfromthePast · 14 February 2006
It seems quite obvious that there was simply an environmental response on the part of Chlorella when in the presence of a predator. It's much harder to "eat" a multicellular globule. It's quite obvious that the "machinery" for responding is "built-in". This isn't evolution in the least.
This highlights the difference between ID and neo-Darwinism: experiments like this are completely misunderstood.
Sir_Toejam · 14 February 2006
PvM · 14 February 2006
Pvm · 14 February 2006
Sir Toejam, that's funny, had not noticed the Freudian slip here. Why is it so hard for ID activists to accept evolutionary theory? I thought that ID embraced evolutionary theory? After all, that's why it presents no real scientific explanations of its own relevant to its thesis.
PvM · 14 February 2006
Sir_Toejam · 14 February 2006
as to why it is apparently so hard to get IDers to recognize the science involved in evolutionary theory, and the tremendous evidence in support, I came to the conclusion long ago that most are suffering from a common psychological disorder.
go take a look at a freshman psych text that goes into standard freudian defense mechanisms sometime.
the physchological pressure these folks feel between their constructed belief systems and the reality of the world as it presents itself to them motivates them subsconsciously to produce ever more extreme and bizarre forms of defense mechanisms.
typically, these seem to take the form of projections, as blast has just so wonderfully demonstrated for us just now, and frequently has in the past.
Denial is also a very common defense mechanism among many ID supporters.
I swear, someone could easily write a series of papers extolling the remaining virtue in freudian psychology simply by using creationists as a research group.
PvM · 14 February 2006
PvM · 14 February 2006
Wikipedia has some interesting stuff on cognitive dissonance see also here
Our minds work in mysterious ways and such little time to learn about all this cool stuff.
Sir_Toejam · 14 February 2006
BlastfromthePast · 14 February 2006
AD · 14 February 2006
Jason · 14 February 2006
Test it yourself! That's too much. I'm sorry.
And btw, of course, I think ID is a waste of time and can explain nothing, but please...
Sir_Toejam · 14 February 2006
BlastfromthePast · 14 February 2006
BlastfromthePast · 14 February 2006
Sir_Toejam · 14 February 2006
putting quotes around a word does not totally change its meaning, except maybe in your own mind there, blasty.
it implies the word generally fits the category of usage, with exceptions.
however, in the way you use it, you might as well have used the word "metallic".
you selective use of quotes around words only serves to indicate the spots where you are selectively applying your very own constructed perceptions.
hence that's why i made a point of it.
you exhibit this behavior commonly. perhaps without even realizing it. You ARE suffering from a form of dissonance.
As to whether that's curable or not, you'd have to visit a mental health professional.
no shame in that; mental illness is just like any other physical ailment.
I wish you luck.
AD · 14 February 2006
BlastfromthePast · 14 February 2006
Dear AD:
Bile does not substitue for erudition. So try a different tact, please.
(1)"You disparagingly called something a guess, with the implication being that it was obviously unfounded." Just because you don't like it doesn't make it anything different than a "guess". So what if it's an educated guess. Isn't science supposed to move us beyond guesses? And it's only an "educated" guess if you believe that RM+NS actually does miraculous things. I don't happen to believe that. And you don't have "proof" of that: you have "educated guesses". That's not sufficient. Sorry. What rule says that induction has to act quickly? In fact, to turn the tables on him, there's every good reason to expect "induction" not to take place quickly if, in fact, the 'colony' form persists for two years as he states. If it's so hard for the organism to go back to the unicellular form, then it might have a very high, complex, threshold for "switching" over to the multicullular form.
(2)"A mutation, by definition, is contained within one strand of DNA. This is why your question is nonsensical." Am I to understand that just because some scientist says "evolution did it", that I am to assume that a mutation occurred, and that that mutation brought about the observed change? Where is the mutation? What was the sequence change? What does it look like? Or am I simply to take it on "faith" that somewhere, somehow, a cytosine molecule changed to a glycosine, and voila--multicellularity. I'm simply not that gullible. Again, sorry.
(3) "Secondly, when I said "IF that were true" I was alluding to your previous statement, with the implication being that it was not, in fact, true." I apologize. I did misread what you wrote. Part of the reason for that is that the reasoning that Borass uses is a little bit far-fetched; viz., just because a response didn't happen quickly, it's not induction?
(4) "They weren't using the generalized meaning. If you try to apply a generalized meaning to their argument in response, you're just plain wrong." Now let me see. They say that in order for the "colonies" to persist, the predator has to be present. And when the predator is taken away then the colonies go away. Is there not enough room in the word "induction" to cover such a situation? The only reason that they don't use "induction" is because it took 20 generations to bring about an initial change. To them that's "proof" that "induction" didn't take place. Again, where's the rule that says that "induction" has to take place quickly?
(5)"Also, I notice you still have not offered to perform any experiments or back up your conclusions, when the burden of proof is upon you."
Tell me: what have they "proved"? Have they proved it was an "mutation"? No: it's an "educated" guess. Have they proved that some process of "induction" is involved? No, they simply infer that "induction" ought to occur more quickly. It's not me that needs to "prove" something; it's them. They're simply postulating a mechanism--i.e., hand-waving. Sorry, I'm not that gullible.
Here is this great irony: the neo-Darwinists claim that science will come to a halt if IDers take over (they're creationists, after all), and what we end up seeing is neo-Darwinists coming to a standstill in the laboratory because RM+NS says the problem's solved. Well, it isn't solved. There are a lot more questions to be pursued.
And I stand by my initial assessment: this phenomena is, plain and simple, an induced reaction by the chlorella in response to an environmental stimulus. Prove me wrong!
As I said above: isn't science supposed to move us beyond guesses?
BlastfromthePast · 14 February 2006
PvM · 14 February 2006
Ah, the sound of denial... A first step towards recovery from cognitive dissonance
PvM · 14 February 2006
PvM · 14 February 2006
PvM · 14 February 2006
And it either way the response is induced then why are we arguing? You seem to be suggesting that your induction idea is similar to the selection argument?
BlastfromthePast · 14 February 2006
PvM: You're always even-headed and open-minded. Good for you.
You wrote, in relation to the possibility of "induction": "Nope, they gave four reasons. Have you not been following the discussion?"
Well, here's the problem:
Thirdly, when the colonies are cultured in the absence of any source of an inducing substance, the colonies 'breed true'. The colonial Chlorella morph remains colonial both on agar and in monospecific liquid culture, including chemostats where steady states have beenmaintained for several months. . . . (later on)This shows that active photosynthesis by the algae and continued interaction with the predator are essential to maintain the colonial algae in continuous culture.
This doesn't seem to rule out the possibility of the predator flagellate being the "inducer": meaning that it interacts with chlorella, either directly or indirectly, bringing about a pre-packaged response in the Chlorella.
Is there some technical detail I'm missing here?
'Rev Dr' Lenny Flank · 14 February 2006
Jason · 14 February 2006
Jason · 14 February 2006
Sir_Toejam · 14 February 2006
PvM · 14 February 2006
PvM · 14 February 2006
AD · 15 February 2006
PvM, you are more patient than I.
I think, however, Blast's comments have made the case against him far better than anything else I could continue to say in this thread, so I'm done here. Either way, I firmly believe an unbiased reader would very quickly be able to determine which side was playing fair and presenting rational arguments, and which side was not.
Enjoy.
Rilke's Granddaughter · 15 February 2006
ben · 15 February 2006
William E Emba · 15 February 2006
BWE · 15 February 2006
pondscum · 15 February 2006
As an addendum to the discussion of NS in Chlorella, algal biologists, particularly those that cultivate unialgal and axenic lines, have been aware that changes do occur. A quick survey of the UTEX culture collection identifies several strains that have lost the ability to reproduce sexually or to form stages typical of the original isolate. Of course, asexual reproduction continues to work like a charm. While the loss of sexuality is an annoying issue for researchers interested in studying sexual reproduction in these cultivated lines, it offers strong support to the notion that mutation and selection have been at work. One might ask why these putative mutations haven't been identified. Well, largely because its costs big $$$ to do a genome. The Chlamydomonas reinhardtii genome is just now being annotated---this would have to be our starting point, but we still know so little about any algal genome. So many mutations, so little time and money.
Jason · 15 February 2006
Jason · 15 February 2006
Colony above should read "culture."
Sir_Toejam · 15 February 2006
Henry J · 15 February 2006
IOW, those mean scientists just ruined the sex lives of those poor critters... ;)
Henry
Anton Mates · 15 February 2006
Henry J · 15 February 2006
Anton,
Actually, my "those mean scientists just ruined the sex lives of those poor critters"
was referring to pondscum #80171 "A quick survey of the UTEX culture collection identifies several strains that have lost the ability to reproduce sexually or to form stages typical of the original isolate"
rather than the Chlorella.
Henry
Anton Mates · 16 February 2006
PvM · 16 February 2006
Anton Mates · 16 February 2006
BlastfromthePast · 16 February 2006
There's this statement from the paper: "Thirdly, . . . The colonial Chlorella morph remains colonial both on agar and in monospecific liquid culture, including chemostats where steady states have beenmaintained for several months . . . ."
And then there's this statement:
"This shows that active photosynthesis by the algae and continued interaction with the predator are essential to maintain the colonial algae in continuous culture."
If you put the two statements together it seems to imply that the predator was present as well when the Chlorella "bred true" on the culture and agar.
If that were the case, then this doesn't seem to rule out the possibility of the predator flagellate being the "inducer": meaning that it interacts with chlorella, either directly or indirectly, bringing about a pre-packaged response in the Chlorella.
Another nagging question is whether or not the presence of the unicellular form of Chlorella is a trigger for going back to the unicellular form. If the predator is present in the culture/agar mediums, then even if the 'inducer' is absent, the signal to return to unicellular form--that is, the unicellular form of Chlorella--would never be present since it would be devoured by the predator. That's why I think it's important to know whether the predator was present during the two years of 'breeding true.'
Further, it is clear that we're not dealing with some kind of 'pherome' issuing from the predator that 'induces' the colonial form of Chlorella. But perhaps the "inducer" is something that is exuded/produced/spilt out from the dead prey. Or perhaps it's something that the predator produces--excrement--that has some residual substance from the devoured Chlorella. (If the latter case holds, is this then why it takes 20 genertations before it switches over to the colonial form?) If that's the case, then in the presence of the predator (1) the unicellular form will be triggered to go to the colonial form, and (2) in the continued presence of both unicellular Chlorella and predator, the colonial form will persist.
So, to me, it's absolutely critical to know whether or not the predator was present when the colonial Chlorella was 'breeding true'. And I think it would be great to run the experiment again, and this time, once colonization takes place to remove the predator and "flood" the colonial form with the unicellular form to see whether, indeed, the unicellular form does act as a trigger back to the unicellular form.
sonofblast · 16 February 2006
blast
Social amoeba, a model organism for the colonial theory of metazoan evolution, are normally a free living animal that lives in forest soil. When food runs short they send out a chemical "call to arms" where millions converge and form a "slug". Some of them then modify their cellular structure into hard cell walls to form a stalk that pushes up above the soil and others at the tip of the stalk become spores and are (hopefully) transported to a better food supply to continue the species.
The amoeba that form the stalk die. The process of forming a rigid cell wall is irreversible. The rest of slug, once the spore creation is finished, return to being free living cells for whatever fate awaits them (presumably starvation since that's what triggered the slug formation in the first place).
I doubt like the algae evolved under the researcher's nose. An environmental trigger caused the transition to colonial behavior sure as I'm sitting here writing this.
sob
Anton Mates · 16 February 2006
Anton Mates · 16 February 2006
MP · 16 February 2006
Just some thoughts from a lurker...
If blast feels that an educated guess is no more valuable than a baseless guess, then I suggest he immediately cease using, and avoid future use of, any products that require extensive engineering, especially stuff that's innovative. No planes, autos, computers, etc for you, M. Blast, because they were all designed using educated guesses, but we in the biz call it engineering judgment. Especially stay away from aircraft. I recall an aero-engineer once saying, " After a hundred years of flying, we still don't know exactly what makes a plane fly." Just remember that the next time you jump on a plane, and pray to your designer that educated guesses really are more valuable than uneducated ones.
On a related note, blast said,"And I stand by my initial assessment: this phenomena is, plain and simple, an induced reaction by the chlorella in response to an environmental stimulus. Prove me wrong!"
Based on the above statement, my assessment is that thousands of invisible pixies carry planes to make them fly. Prove me wrong!
BlastfromthePast · 16 February 2006
Anton:
I'm going to intersperse my comments among your last post. I think it'll be tidier that way.
"Thus they showed that the multicellular morph breeds true in a variety of culture setups even when the flagellate predator is absent.
I'm not sure you read all my comments on the last post. One of the things I suggested is that it is the 'presence' of the unicellular form that triggers the decline in the colonial form. I know you address this down below--and I'll respond to that portion below--but I just want to make sure you're aware of the point I was suggesting.
It's true that their second statement is slightly overgeneral---they mean you need the predator to maintain the colonial algae in continuous culture setups where there's also a permanent source of unicellular Chlorella, either from a previous stage or (as is likely if this is the same chemostat where your multicellular morph originally popped up) as a small remnant population.
A question here: (not sarcastic) How do you know that's what they mean? I don't necessarily disagree; in other words, is there something I've missed? Now assuming what you say is actually the case, then the suggestion remains that the predator is needed to eliminate the presence of the unicellular form amongst the colonial form or else the colonial form will disappear. How do you respond?
That's clear from their description of the two-stage chemostat in which the multicellular morph was seen to wash out.
It's not clear to me (again, not sarcastic) because they seem to imply that the only reason the colonial form disappears is because of the absence of UV for photosynthesis. They don't appear to mention any other reason.
That morph disappears not because it reverts to a unicellular form but because such a culture already contains unicellular morphs which can now outcompete it.
I'm not sure what you mean here. Is this just you're impression (again, not sarcastic), or is there something that makes this clear? (BTW I'm working on the excerpts that have been posted here; I don't have access to the article. Maybe you do. If so, is there a URL I can use?) Are you talking about the two-stage chemostat? If you are, again, isn't the reason they die the absence of UV?
I think knowing the conditions under which the colonial form reverted is vital to the interpretation.
Russell · 16 February 2006
Henry J · 16 February 2006
Re "One of the things I suggested is that it is the 'presence' of the unicellular form that triggers the decline in the colonial form."
A thought here: if the mix of unicell and multicell versions is now in an environment in which the unicell is more successful, then perhaps the multicell form declines simply because it is being outcompeted for the available resources? (I.e., not because of any conversion from one form to another one.)
Henry
BlastfromthePast · 16 February 2006
Henry wrote: "A thought here: if the mix of unicell and multicell versions is now in an environment in which the unicell is more successful, then perhaps the multicell form declines simply because it is being outcompeted for the available resources? (I.e., not because of any conversion from one form to another one.)"
Can't discount it. If there's some interaction between predator and prey which 'triggers' the colonial form, and if the presence of a considerable amount of unicellular Chlorella 'triggers' the multicell to become unicell, then you have a situation where the unicell Chlorella will begin to take over once the predator is removed and as a result the multicell will decline--if the 'trigger' system really applies. So your left with trying to decipher if the decline is NS--i.e., the unicells have an advantage--or, if a signal has been sent. How do you distinguish?
I wonder if you could culture the unicell form, place in the dark until even the unicell died, and then take that solution and add it to a multicell culture and see how the multicell forms react. If, indeed, there's a signal chemical/pherome of some sort, then it might just get the colonial form to decline in the absence of competition for nutrients with the unicells. But, of course, nothing might happen; the colonial form could just continue along; and then you don't know what to conclude.
Anton Mates · 16 February 2006
Anton Mates · 16 February 2006
BTW, I was unable to find anything in the Journal of Phycology on keying out the colonial Chlorella morph, nor did I find anything like that in papers citing the Boraas papers. So if you get a reply, Pim, I'd love to hear it. Otherwise I guess I'll write talk.origins and suggest that claim be taken out.
Jason · 16 February 2006
Jason · 16 February 2006
Sir_Toejam · 16 February 2006
bloody pant-loading nonsense.
that's exactly why we take a poke at these types of arguments.
they simply don't EVER hold up when push comes to shove.
go find ANY reputable study that supports the idea of pant-loading.
we've been all through this with blast; remember front-loaded snake toxins, blast?
give it up, really.
Anton Mates · 16 February 2006
Anton Mates · 16 February 2006
Anton Mates · 16 February 2006
Jason · 17 February 2006
Jason · 17 February 2006
Something just dawned on me.
They said they reproduced the experiment many times and got 8-celled colonies about 70% of the time.
Does that mean that each one of those cultures with 8-celled colonies represents a new species? So that there are many many different species of 8-celled colonies? Or did mutation and selection converge on the same species time and time again? That seems highly unlikely (notice I didn't use the ID line of it's so unlikely as to be impossible since that's BS.)
PvM · 17 February 2006
Anton Mates seems to have answered most if not all objections by Blast and Jason. If I have missed any please repeat them. Yes, the multicellular form remains multicellular even away from the predator. The confusion may have been when discussing the dual stage chemostat experiment where the two forms do compete.
Interesting tidbit is that the original paper was based on an experiment where the second stage which contained the predator backflushed into the primary system, which almost by chance led to an interesting experiment. Even if the two are still considered the same species, the step from single to multicellular should be seen as a major innovation.
Anton Mates · 18 February 2006
BlastfromthePast · 18 February 2006
PvM · 18 February 2006
PvM · 18 February 2006
Anton Mates · 18 February 2006
BlastfromthePast · 18 February 2006
PvM · 18 February 2006
Sir_Toejam · 18 February 2006
steve s · 18 February 2006
'Rev Dr' Lenny Flank · 18 February 2006
Anton Mates · 18 February 2006
BlastfromthePast · 19 February 2006
Sir_Toejam · 19 February 2006
'Rev Dr' Lenny Flank · 19 February 2006
'Rev Dr' Lenny Flank · 19 February 2006
BlastfromthePast · 21 February 2006
Sir_Toejam · 21 February 2006
'Rev Dr' Lenny Flank · 21 February 2006
BlastfromthePast · 21 February 2006
'Rev Dr' Lenny Flank · 21 February 2006
Sir_Toejam · 21 February 2006
'Rev Dr' Lenny Flank · 21 February 2006
BlastfromthePast · 22 February 2006
Sir_Toejam · 23 February 2006
Sir_Toejam · 23 February 2006
blast, your starting to affect my mental states.
please replace it's with its.
ack.
Sir_Toejam · 23 February 2006
hmm, how many errors can i make in a single paragrah...
replace your with you're...
Anton Mates · 23 February 2006
BlastfromthePast · 23 February 2006
Sir_Toejam · 23 February 2006
Sir_Toejam · 23 February 2006
remember that word, blast...
projection.
when you accuse US of being biased, when most of us who criticize your front loading crap have ALREADY studied the relevant literature for years, that's called projection.
any wonder why you piss so many of us off?
90% of your "arguments" essentially stem from projection on your part.
it gets tiresome to keep correcting you all the time.
not that you care, but i guess Anton does.
Sir_Toejam · 23 February 2006
Sir_Toejam · 23 February 2006
interesting=>interested.
Sir_Toejam · 23 February 2006
Anton Mates · 24 February 2006
BlastfromthePast · 24 February 2006
Anton Mates · 24 February 2006
BlastfromthePast · 24 February 2006
Anton Mates · 25 February 2006
BlastfromthePast · 27 February 2006
Anton Mates · 28 February 2006
Anton Mates · 28 February 2006
Anton Mates · 1 March 2006
BlastfromthePast · 2 March 2006
Steviepinhead · 3 March 2006
Memo to Blast:
Hey, kid, Ghost of Paley--stooping to steal a page from the Book of Larry--is mimicking you. Ya better fill the internet lines with the fear and trembling of your retro presence until Ol' Ghosty ceases and desistses.
Up with Psuedo-Blasts, we will not put! That would be like letting Lenny's Pizza Guy get away with a slow pasta delivery to Lenny, based on the whine that Lenny loaned him a leaky kayak, resulting in sore shoulders and a general bad attitude on the part of Pizza Guy... We don't let anyone get away with whining or deceiving, not the evo-devo good guys, and not even the regulars and, yes, the protection of our "anti-deception policy" most certainly likewise embraces our favorite trolls: youse wise guys better not crowd in here trying to poach on our trolls, no siree ma'am!!
BlastfromthePast · 3 March 2006
Anton Mates · 3 March 2006
Anton Mates · 3 March 2006
Anton Mates · 3 March 2006
BlastfromthePast · 4 March 2006
'Rev Dr' Lenny Flank · 4 March 2006
Hey Blast, why does Dr Fry (and all the other working scientists you've engaged here) think you're full of crap?
k.e. · 4 March 2006
Well Blasty long time no see.
what have you been doing ---arguing with your Quantum Physics teachers ?
So how is the quest for the "Holy Grail" going?
I see you have re-entered the enchanted castle and YOU STILL HAVEN'T asked the question.
Ho Hum.... well at least you made the mistake of saying something true for a change
They shouldn't call it 'evolutionary theory', they should call it a 'theory that evolves.'
Tuff sh*t old son..... thems the breaks.
You know you could fix this whole thing right now if you wanted.
Look up Parsifal's Question.
Faidon · 4 March 2006
BlastfromthePast · 5 March 2006
Anton, throughout this discussion, you have steadfastly maintained that what we see in this experiment is no more than some kind of series of mutations taking place in the 'unicell' Chlorella population. You have taken the position that these mutations were not there before the predator was introduced. You believe that the 4-cell, 8-cell, 24-cell, 100+-cell 'colonies' of Chlorella are no more than different mutations. You also believe, as the authors do, that NS has caused the 'fittest' form, the 8-cell 'colony' to become dominant.
I have steadfastly maintained from the first time I read of this article that this is a case of chemical induction---knowing nothing of other predator-prey experiments in which chemical induction was shown to be the case.
Rather than letting this go on forever, I now plan on presenting irrefutable evidence---based strictly on the data that Boraas provides---that the colonial form of Chlorella is chemically induced.
I. The first place to start is with the statement, p.160, where it is said: "After about 10-20 generations in the presence of the phagotroph, an eight-celled Chlorella 'colony' became the dominant phototroph in all replicates of this experiment."
Phrased another way---a way which should have guided Boraas, et. al.'s thinking---EVERY TIME the experiment was conducted, an 8-celled colony ensued. This bespeaks chemical induction: you introduce the phagotroph, and 8-celled colonies are produced, EACH and EVERY TIME.
This is in contrast to "multicells"---which Boraas doesn't do a good job of describing, but from what is written and 'shown', namely Fig. 1 a.,--that is, colonies greater than 24 cells. "Mulitcells" are found only 70% of the time. So, for 30% of the time, "multicells" have nothing do with the mechanisms at play in this series of experiments.
Again, 8-celled colonies are found 100% of the time.
II. Next, let's examine what Boraas means by 10-20 generations. It would be wonderful if he would tell us what the doubling time is for the Chlorella. But he doesn't. But looking at Figure 2a., and by simple calculations based on the percentage increase in the unicell population after it was grazed down by the Ochromonus, the doubling time (time per generation), is a little more than a day. So let's round down to a day.
Now, let's address another part of the above statement: "in the presence of the phagotroph." This implies (and in the discussion this is also apparently what Boraas thought) that the phagotroph excretes some chemical that 'immediately' affects the unicell population of Chlorella. But from other similar experiments, it's been demonstrated that the 'inducing' chemical is something that is the product of prey digestion in the predator.
It is fair to assume that for chemical induction to occur, time must be allowed for: (1) the predator to digest the prey. (We don't know. Let's assume it takes a day), and (2) a build-up in concentration of the inducer. For both condition (1) and (2) to both occur, we need probably 2-3 days. I think this a conservative, fair assumption.
Now, let's look at Fig. 2a. We see a peak in the 'unicell' at 10 days from introduction of the phagotroph. But just letting your eye move down that time line of 10 days: we also see peaks in the 20, 22, and 25 micrometer range. Boraas states on p. 155-7 that "the prey Chlorella now included colonial growth forms as well as unicells (10 days, Fig. 2a). The number of cells per colony ranged from four to hundreds (Fig. 1c), and bracketing and masking the flagellate size distribution. (Fig. 2a)"
Using the lower value for generation time, this all occurs at a maximum of 10 generations after the introduction of the phagotroph. But, as I've explained above, this number should fairly be reduced to 7 generations (or less). Now, according to your assumptions, a mutation has occurred in ONE of the 'unicell' forms which gives rise to the 4-cell, another mutation that gives rise to the 8-cell, another to the 100+-cell, etc. In the description box at the bottom of Fig 2a/b, it is stated that "(t)he majority of Chlorellacells were in colonies with more than 24 cells per colony for the first month of culture." Notice that 100+-cell 'colonies' are ALREADY seen at the 10 day mark. And according to geometric growth, that's 2^7 times growth starting with one dividing 'mutant' cell; in other words, 7 generations worth of growth.
But that is for ONE mutation, resulting in ONE colony. We know that the initial 'unicell' Chlorella density is 2 x10^6 cells/ml. It then shrinks to 0.1% of that original density. However, at the 10-day mark, it's at a value that appears to be almost equal to that initial value: 2 x 10^6 cells/ml. The culture tube volume is said to be 'volume constant at 500ml." The most likely situation is that it contains 500 ml. of liquid. But to take a conservative approach here, let's assume it's only 250 ml. of liquid in the culture tube. That means there were---at the 10-day mark---5 x 10^8 'unicells' present in the culture tube. Fig 1a. shows the 8-cell size at half that value at the 10-day mark, and the 24-cell value at slightly less. Let's call the 24-cell value, conservatively, one-fourth of the "unicell" value: that is, 1.25 x 10^8 cells. If we look, now, at Fig 2b, we notice that at the 12 day mark that the 24-cell value is about twice the 100+-cell mark. Assuming a proportionate response between Day 10 and Day 12, that means that the 100+-cell value at the 10-day mark would have been 1/8th of the 'unicell': that is, approximately, 6 x 10^7 cells in the culture. But it takes SEVEN generations to produce ONE 100+-cell from 'one' mutated cell. So, to back into how many "mutated cells" we need at Day 3 (when the predator's effect is first felt), we take the 6 x 10^8 and (again, to be conservative) divide by 200 (even though the biomass of a 100+ cell is perhaps not equal to 100 times the 'unicell' biomass volume since the 'colonial' cells seem smaller in size compared to the 'free unicells." (FC in Fig. 1a) Otherwise, we would divide here by 100 [100 'unicells'per 100-cell 'colony'], and not 200), giving a value of 3 x 10^6 cells.
You have assumed the 'mutations' have been 'induced', hence, to explain these numbers, we need 3 x 10^6 'unicells' "mutating" in such a way that ALL these 3 x 10^6 'mutations' have the same phenotypic effect; viz., 100+-cell 'colonies'. This is simply IMPOSSIBLE---no matter how many 'hundreds' of ways a genome can mutate.
If you want to maintain that the mutation was already there ahead of time (as Pim does), this 'conservative' number is only 1/250 th (inverse of the culture tube size assumed here) of the original density of the 'unicell'. Certainly it would have been seen. Fig 1a was taken 240 days after inoculation, and we see a 24-cell 'colony', at a time when the 8-cell was, according to Boraas, dominant, while we were also told that for the first 30 days the 100+-cell 'colonies' dominated.
'Mutation' of the 'unicells' cannot explain the data that is reported.
III. A simple further proof that 'mutation' cannot explain what we see reported is the VERY PRESENCE of a 24-cell 'colony', let's notice that that is NOT a 'power' of 2. The progression is 2, 4, 8, 16, 32, 64, 128. If we look at Fig 2b, notice that at the 12-day mark there are NO 16-cell 'colonies'. If a 'mutant' is going to produce a 32-cell colony, or a 64, or a 128-cell colony, it MUST pass through the 16-cell stage. There's no other way possible. Look again at the 24, and 20-cell 'colonies'---NEITHER of these are multiples of 2. How can it be maintained that something other than an 8-cell 'colony' is 'growing' when there is no evidence, whatsoever (!!), of the 16-cell stage?
Is this some kind of extravagant claim? Well, let's take a look at Figure 1. Look at 1a. Doesn't that look like a 24-cell colony? And doesn't it look like a cluster of three 8-cell 'colonies'? Look at 1c. Doesn't that look like a collection of 8-cell 'colonies'? And since basic biology says a cell can't divide in half a multiple number of times and reach a 24-cell stage, the only LOGICAL explanation is that the 24-cell 'colonies' are made up of 3 clusters of the 8-cell 'colonies.' The 20-cell 'colonies' are a combination of two 8-cell 'colonies' and a 4-cell 'colony'.
This can all be simply explained as a change to the mother cell wall coming about via chemical induction.
IV. Lastly, let's take another look at Fig 2b. Notice that around Day 45-50, the 8-cell 'colonies' have the 'dominating' the "biomass volume". But also notice that there are "biomass volume" peaks at the 20-cell and 24-cell 'colonies'. And remember Fig 1a. There we see a 24-cell 'colony' after 240 days after inoculation, a 'colony' that clearly looks like three clustered 8-cell 'colonies.'
To sum up:
1.) In EVERY replicate of this experiment, the 8-cell 'colony' is observed and becomes permanent.
2.) The presence of 100+-cell 'colonies' cannot be explained via the 'mutation' of the Chlorella 'unicells' either through 'induction' by the presence of a predator, or through these 'mutations' being present in the culture before the experiment began.
3.) Photographic evidence strongly suggests that clusters larger than the 8-cell 'colonies' are the product of a clustering of 8-cell 'colonies'. The persistent presence of 24-cell 'colonies', which defies the geometric progression of cell division, buttresses this observation.
This not only rules out RM+NS, it paves the way to proving a chemical induction scenario for what is observed.
That scenario goes like this:
If the presence of the predator-prey by-product is the 'trigger' for a change in thickness/stickiness of the 'mother cell wall' of the Chlorella, that 'trigger' would likely have come about in Day 3. This 'signal' affects all 'unicells' that will go on to become 'mother cells'. The ones that do not become 'mother cells' are 'grazed down' and stay in a steady-state with the Ochromonus. The 'mother cells' that respond begin to divide. Normally, the 'mother cells' contain 2-16 cells. With chemical induction having taken place, some of the mother cells continue to divide and grow, reaching the 16-cell count wherein it 'bursts' in half. But now, since chemical induction has occurred, the membrane 'sticks' to the cells, forming 8-cell 'colonies'. It's possible that some 'mother cells' burst at the 8-cell stage, thus forming 4-cell 'colonies.' The remaining colony cell numbers, in particular the 24-cell 'colony', come about by 8-cell 'colonies' 'sticking' together. In the transient period, 'stickiness' prevails, and large-celled 'colonies' (over 100 cells) occur. [N.B. this 'transient' period could be---and I would go so far as to say, probably is---attributable to this experiment being performed in a 'culture tube', rather in a natural planktonic environment.] In the end, the 8-cell 'colony' predominates in EVERY experiment run.
One important final word: the clear indicator between the 'unicell' morph and the 'colonial' morph is the presence of 'empty' 'mother cells.' It is noted that in the 'unicell' culture, empty mother cells could be seen, whereas when the 'colonial' form is present, NO empty mother cells are detected. This is easily explained---almost predicted---from my proposed mechanism in the above paragraph.
That is why it is of paramount importance to know what happened in the chemostat when the phagotroph was removed and the 'unicellular' form and the 'colonial' form were present together. In the absence of the predator-prey chemical inducer, AND, in the presence of a normal, almost background, signal that the 'unicellular' forms produce, one would expect that the 'mother cell walls' would be affected, they would return to their normal condition, AND...... 'empty' 'mother cell walls' would begin to be seen.
Isn't it interesting that when it comes to this absolutely important information we're simply told, "In experiments where the unicells and colonies were placed in competition in the absence of the phagotroph in the LIGHT, the multicellular form was slowly displaced by unicells (data not shown)."
As to Boraas' principle reason for claiming that 'induction' has not occurred, I think he has made two mistakes. First, he assumes that the 'induction' begins 'immediately' with the introduction of the phagotroph. Other experiments demonstrate otherwise. It is very likely that the 'signal' for the 8-cells comes when the 'unicells' have been 'grazed down' to its steady-state density. This is 5-days after the phagotroph is introduced. Second, he assumes that the 'induction' is to the 'unicells' directly; but, more probably, it is to the 'mother cell wall.' The effect of that 'induction' is not seen until the first affect 'mother cells' burst. This is at a cell size of 16; that is, 2^4; in other words, after 4 generations. How long does it take for four generations of Chlorella to form? About 4-5 days. Under the proposed chemical induction scenario, one would expect the "8-cell colonies" to appear 9-10 day after the phagotroph is introduced---which is EXACTLY what is seen. Similarly, to 'return' to normal behavior where the phagotroph is absent would be, at a MINIMUM, around 4-5 days. Is that what Boraas means by "slowly displaced"? Too bad there's "NO DATA SHOWN".
In conclusion, there is no question that what we're seeing in the Chlorella is some kind of chemical induction, likely to the 'mother cell wall.' RM+NS cannot explain the data that is presented here. Photographic evidence supports this conclusion.
This paper passed peer-review. PTers/Darwinists make a big deal of peer-review. What this paper demonstrates is that the Darwinist world-view blinds scientists---both the authors and the reviewers---from taking a critical view of data.
As far as I'm concerned, the discussion of this paper, and the chemical induction vs. RM+NS interpretation of this paper, are concluded. The conclusions I've made above are clear-cut and irrefutable.
Case Closed.
PvM · 5 March 2006
Sir_Toejam · 5 March 2006
Faidon · 5 March 2006
You know, call me naiive, but until now I had this hope Blast might actually be serious and have some genuine views to uphold, however wrong- not just some clueless geek trying to gain impressions. Oh well.
BlastfromthePast · 5 March 2006
BlastfromthePast · 5 March 2006
PvM · 5 March 2006
BlastfromthePast · 5 March 2006
BlastfromthePast · 5 March 2006
PvM · 5 March 2006
PvM · 5 March 2006
So let's accept BlastFromthePast's argument that the reponse was induced chemically. What does this mean for Darwinian theory?
While initially epigenetically controlled, the stability of the 8 cell variant shows that selection and variation eventually led to a significant novelty namely multicellularity.
Evolution works in mysterious ways :-)
How does ID explain this?
Realize that the step from single to multicellularity (coloniality) was the first step. Next step is cells taking on specialized roles. Science is slowly unraveling these mysteries.
ID seems to remain well, a bit vacuous.
BlastfromthePast · 6 March 2006
PvM · 6 March 2006
Sir_Toejam · 6 March 2006
Sir_Toejam · 6 March 2006
PvM · 6 March 2006
BlastfromthePast · 6 March 2006
Russell · 6 March 2006
I don't have the patience to read all the way through what looks like yet another tedious grasping at straws by Mr. Blast. So forgive me if this has already been asked and answered.
But if Blast favors this "induction" hypothesis, and looks to my cursory examination to be determined to shoehorn the evidence into that explanation, what tests does he propose that could potentially disprove it? (You know, that "falsifiability" thing.)
BWE · 6 March 2006
or, for that matter, "prove" that it is the best hypothesis?
Ha ha.
Popper's Ghost · 6 March 2006
Popper's Ghost · 6 March 2006
P.S. This is obviously (to any honest person) not a definition of "colony", but rather a description of the colonies that were observed. "colony" is presumed to have its usual meaning.
Anton Mates · 6 March 2006
PvM · 6 March 2006
Nice analysis Anton. Indeed, the two statements do not conflict *if* read correctly.
W. Kevin Vicklund · 7 March 2006
Sir_Toejam · 7 March 2006
Popper's Ghost · 7 March 2006
BlastfromthePast · 7 March 2006
k.e. · 7 March 2006
Gee Blast wedged again what's your average now... twice a month ?
By induction you seem to have some impermeable and false beliefs that if not changed will lead to an even more tenuous grasp on reality..... if that were possible.
At least you are not projecting your completely useless religious beliefs as science facts, you know the one about "for 150 years now creationist's have been denying evolution...blah blah blah" have you given those up ?
Good for you if you have....uh oh ...wait a minute.... induction? hahahahahahaha.
Yes the easily debunked Dembski/JAD "if we can only come up with a way of describing evolution without motioning anything about it and/or if we have to.... use a negative or counter argument, that is ......wait for it.....(lights, trumpets, clarions)....TADA.... deduction and thus irrefutable
goder the Karl Lagerfield/Christen Dior of nature exists NOW MORE FASHIONABLE, ready to wear Creationism.PLUS THE DESIGNER HAS A PhD. heck he has two of them. One in basic plant's and animals and the other in his SPECIAL SUBJECT HomoSapiens.
Roll up roll up get your designer books here. Our motto is "We may have designs on your money but hey YOU WILL FEEL BETTER !
No this is not your dusty old Sunday school version of the pre Star Wars version of an unshaven Alan Greenspan in drag doing god but the new Hip cool (and white male sensitive new age redneck) version of god .....oh did I mention he was intelligent ?
Well maybe but only if you count a basic good education as a mark of intelligence heck some of those guys have one or two Ph.D's
Let us know how you are going to fix Quantum Mechanics the same way you have irrefutably smirk fixed biology.
Good luck there are even more loonies, crack pots and pseudo scientists on that circuit but there are a few who have really, really, really sorted it all out have you heard of Dr Quantum ? he has a PhD. and met Werner Heisenberg really and he has 11 books. WoW Blast when are you going to give us your pearls in a book ?
k.e. · 7 March 2006
motioningmentioning ....stupid spell checkerBlastfromthePast · 7 March 2006
PvM · 7 March 2006
PvM · 7 March 2006
pvm · 7 March 2006
BlastfromthePast · 7 March 2006
All of you keep harping on this 70% of multicells thing.
A clear reading of the text demonstrates, unequivocably, that the authors refer, at times, to 'colonies' and to 'multicells', as well as to 'multicell colonies' (Fig 1c). If they didn't want to distinguish between 'multicells' and 'colonies', then why introduce BOTH terms? Why didn't they just talk about 'colonies', or just talk about 'multicells'? The only conceivable reason is that they are making some kind of distinction.
Thus, when they say that 'multicells' appeared in 70% of the replicates, and then say that an 8-cell colony became the dominant phototroph in ALL replicates, why is it you infer that the 8-celled colonies only appeared in 70% of the replicates? How does this follow?
Fig. 1a shows an Ochromonus, and what appears to be a 24-cell Chlorella form which they label a "Chlorella colony". That also would be a phototroph--still there after 240 days after inocculation with the Ochromonus. It isn't called a 'multicell'. Again, in all replicates the 8-celled became the dominant phototroph. After 240 days, there are 1-cell, 4-cell, 8-cell and 24-cell phototrophs present. And the 8-cell is dominant. The language is clear. So the onus is on you to prove that when the authors were talking about 'multicells', they really meant 'colonies'.
Prescinding from the above argument, all of you are argue that the fact (which is clearly in dispute if it is to mean 8-celled colonies as well) that the Chlorella only became 'multicell' in 70% of the replicates is 'proof-positive' that this isn't 'chemical induction.'
Well, if it is 'proof-positive' that what we see in the experiment isn't chemical induction, then why don't the authors state this as the very FIRST reason to discount what they call the 'alternative hypothesis' of chemical induction?
In fact, they don't even cite it as a reason AT ALL to discount the chemical induction idea.
You're all indulging in a strawman argument since you cannot refute the logic I use in positively refuting the idea that the experimental data presented in the paper represents RM+NS. Why don't you admit defeat?
k.e. · 7 March 2006
Blasty I hate to say this about another human but you are Pathologically beyond reason.
EVERY SINGLE argument you have started has been demolished
WHY IS THAT ?
You need to do some real soul searching, start with your own beliefs and question their effect on your motivation and ask WHY it is you keep getting every view of the world you construct in your mind ....inside out and backwards.
Popper's Ghost · 7 March 2006
BlastfromthePast · 7 March 2006
Sir_Toejam · 7 March 2006
Steviepinhead · 7 March 2006
It pays to recall underlying motivations.
What's really got Blast's knickers in a bunch is the ramifications of this interesting experiment: an ecological rationale for single-celled eukaryotes to adopt multicellularity (Natural Selection); and normally single-celled eukaryotes with sufficient variability to accomodate to this environmental stress by, literally, sticking together (Random Mutation).
In short, a feasible and detailed scenario for a key step in the "goo to you" evolutionary sequence. One that shivers the deepest foundations of Blast's world-view; one that, from Blast's perspective, threatens his very soul.
He simply cannot abide this result (any more than Paley's Ectoplasmic Essence could abide the sea-to-land transition of tetrapods, another key step in the same evolutionary sequence, and one which is also coming into ever-sharper focus, and becoming ever more difficult to deny...).
Shocked to his core by this gut-punch, Blast has only two choices, one of which--reformulate his entire approach to reality--Blast views as equivalent to the the termination of his personality. He is left with no choice, therefore, but to critique, carp, and quibble until the immediate crisis is past.
Anything, in other words, but face up to the immediate implications of the evidence.
BlastfromthePast · 7 March 2006
Sir_Toejam · 7 March 2006
like we keep saying, idiot, if you're so sure you have something to contribute, why don't you?
rather than suffer the slings and arrows of outrageous fortune, why not actually participate in the real world?
go do some friggin' research, or shut yer yap, doofus.
oh, that's right, you'd prefer to take a class in quantum mechanics instead.
you're one pathetic waste of space, much like all the rest of the IDiots out there who similarly choose to spend all their time whining rather than doing research.
Since you think yourself Zarathustra, why don't you go and prove us all wrong, eh?
BlastfromthePast · 7 March 2006
Sir_Toejam · 7 March 2006
PvM · 7 March 2006
Bruce Thompson GQ · 7 March 2006
Is anyone ready to email the authors with their questions? Or would that take the fun out of the discussion?
Delta Pi Gamma (Scientia et Fermentum)
'Rev Dr' Lenny Flank · 7 March 2006
Hey Blast, why have Dr Fry and every other scientist you have ever talked with here, all unanimously stated that you're full of crap?
Why do you suppose that is, Blast?
Faidon · 7 March 2006
'Rev Dr' Lenny Flank · 7 March 2006
BlastfromthePast · 7 March 2006
Sir_Toejam · 7 March 2006
Sir_Toejam · 8 March 2006
PvM · 8 March 2006
Sir_Toejam · 8 March 2006
BlastfromthePast · 8 March 2006
PvM · 8 March 2006
Sir_Toejam · 8 March 2006
you just can't resist, can you blast?
I thought you were done with us "lowly darwinists" who weren't worthy of the proclamations of Zarathustra?
since you said you had no problems exploring your all too brief graduate career, why don't you want to talk about it now?
PvM · 8 March 2006
And why focus on 24? What about 20 for instance or any other number not a multiple of 2?
Irrefutable evidence ? Or just a bit of grandstanding. Let me give you a hint, there are some good models for prey-predator interactions in a chemostat. Perhaps you should give it a try and see of the numbers do not add up?
I have seen several simulations and actual data which mimick the data observed here quite nicely.
So lets consider some of these ideas you mention that the initial concentration dropped to 0.1% or 0.001 the original value.
You also mentioned 0.004 for the original concentration of the multicellular. This means that the relative concentration went from 0.004 to 4
Somehow these irrefutable numbers do not seem to add up to support your thesis.
Sir_Toejam · 8 March 2006
Faidon · 8 March 2006
BlastfromthePast · 9 March 2006
BlastfromthePast · 9 March 2006
PvM · 9 March 2006
A more charitable reading of the paper suggests that in 70% of the experiments multicells arose, in all of those (70%) cases this included an 8 cell variant which became dominant in all cases.
PvM · 9 March 2006
Anton Mates · 9 March 2006
BlastfromthePast · 9 March 2006
BlastfromthePast · 9 March 2006
Anton Mates · 9 March 2006
BlastfromthePast · 9 March 2006
This Boxhorn fellow is very interesting, Pim.
I've been looking around. Seems like he's very popular at Talk.Origins.com. Does this impeach his objectivity any?
Leaving that aside, I did learn some things.
One thing I learned is that the 'growth rate' on continuous culture is equal to the dilution rate. And the dilution rate is =inflow rate/bottle vol. I learned normal chemostat bottles do, indeed, have a 500ml experimental fluid capacity.
So I looked back at the paper. It seems that they report the inflow rate as 0.035 ml/hr. Well, that's just wrong. This number gives you an unbelievably small growth rate. The number should be 0.035 liter/hr, meaning 35 ml/hr. When you do the calculation, you come up with a growth rate of 1.68 days. We'll call it 1.7 days. This is roughly what I calculated using numbers off of Fig 2a. and 2b. But I thought that too high, based on what the authors had written. But, lo and behold, according to Boxhorn's own calculation, the growth rate (doubling time) is 1.7 days.
If you look at the article, you'll see that the chlorella is grazed down, peaks again, and is re-grazed back down---all in 12 days. As I (conservatively) argued before, we cannot expect any chemical signal to be sent for at least 3 days after inoculation of the predator. According to the paper, after 10 days (p.156-7) "the prey Chlorella now included colonial forms as well as 'unicells' (10 days, Fig 2a). The number of cells per colony ranged from four to hundreds (Fig. 1c)........During a second cycle of flagellate growth and Chlorella decline (16 days, Fig. 2a), the Chlorella colonies persisted while the Chlorella 'unicells' declined to <1% of the total cells in the culture."
So, the first sign of 'colonies' is reported as being Day 10. By Day 16 the 'unicells' were down to <1%. Now 10 days (sighting of 'colonies') - 3 days (when signal kicks in) = 7 days. 7 days/1.7 days/generation = 4.2 generations.
[N.B., I suspect that it takes a combination of a very low 'unicell' "signal", and a very high predator "signal" (which is likely a digestive by-product). Which means that the "signal" for the 'colonies' to form probably didn't happen until Day 5. Then the number of days is: 10 - 5 = 5 days, with a resulting generations number of almost exactly 3. And, of course, to go from 1 cell to 8 cells requires..........drumroll, please...... 3 generations. How interesting, eh?]
Now, here, once again, is the authors' FIRST reason for 'discounting' the chemical induction idea:
"Colonies did not become apparent for about 20 Chlorella generations after inoculation of the flagellates."
Do you see something wrong here?
Was this an honest error?
BlastfromthePast · 9 March 2006
Anton Mates · 10 March 2006
Anton Mates · 10 March 2006
W. Kevin Vicklund · 10 March 2006
Actually, Anton, it appears that from Boxhorn's paper on Talk.Origins, the generation time of a steady-state chemostat is simply the inverse of the growth rate (he was referring to E. coli in the example, but it is apparent that it would apply here as well). So the equation per Boxhorn, correcting for the alleged error, is .035 l/hr / .5 l = .07 per hour. The generation time is therefore 1/.07=14.3 hours. That puts it at just over half a day, which agrees with what I've seen for the max rate. And 20 generations at 14.3 hours/generation = 286 hours, or 11.9 days. Exactly what we expect...
It looks like blast multiplied by 24 to change hours to days (.07*24=1.68).
Even if the flow-rate is as reported, it is not necessarily unfeasible. All it means is that under steady-state conditions, it takes about 600 days for a generation. Throw a predator in there, and the growth rate can jump to max (by all accounts around that magical .07 per hour number) if the concentration of prey falls low enough. While the predator is present, the generation time will actually be higher than inverse of inflow due to predation. The only real fly in the oinment is the predator-less mixed chemostat - we don't really know how fast the replacement occured (though I guess it's possible they stepped up the flow a bit to speed up the process there). But the point is, the growth rate formula Boxhorn gave is only valid for a steady-state predator-less chemostat.
Where the hell did blast get "slowly dissolving" from, anyway? It's not in the article. Anyway, I'm not sure what he thinks the missing data will show wrt empty mother cell membranes. The evolutionary theory would have little to no empty membranes at the start of the predator-less mixed chemostat. The concentration of empty membranes would then steadily rise as the colonies got washed out and the culture was dominated by unicells. Does he think that the induction scenario would predict something different?
Btw, blast, not only did the authors encounter the variant throughout the 20 years, they did so at a rate (2 or 3 times a year) that would be predicted if they took weekly samples.
As far as colony v. multicell, the paper is nonsensical when taken as a whole if they have distinct meanings. Especially when compared to the abstract of the original paper. Sorry, but you are grasping at straws.
Anton Mates · 10 March 2006
W. Kevin Vicklund · 10 March 2006
Sorry, Anton, I didn't mean to sound as if I was disputing the ln(2), I was just stating what Boxhorn implied, and then offering up the results based upon his method, since that is what blast should have calculated. It also gives a longer doubling rate and is therefore more charitable to his argument - yet still whips it like a rented mule.
ln(2)/k makes a lot of sense, because most will not be at time 0 of the reproduction cycle.
k.e. · 10 March 2006
They could always take the "free" legal services of the "Thomas Moore law Center" (giggle) I'm sure those guys will do a *splendid* job.
But they have to take Larry's advice DON'T SAY the G-word....ah that leaves them nothing else to say except we don't know how evolution happened and we don't *like* it....muffle mumble, ace spaliens, tarot cards, astrology, er you know who, wink wink, nudge nudge
In which case if I was on the opposing team I would take the Dr. Miller approach and point out that the stickers don't go far enough and complete the loop by saying evolution is THE ONLY theory that explains ....er how life evolved.
Dem Bones Dem bones Dem Dry Bones
Jaw bone connected to the ear bone Oh hear de word o' de lord.
Dem bones, dem bones gonna vibrate
Oh hear the word o' de Lord
k.e. · 10 March 2006
opps wrong thread ...sorry
Anton Mates · 10 March 2006
Anton Mates · 10 March 2006
Anton Mates · 10 March 2006
Oh, and while I'm looking upthread, I notice that after---what's it been, four months now?---Blast still hasn't managed to answer the question posed to him overhere: If organisms can't evolve from one "kind" to another, as he claims, then does that mean Helacyton gartleri is the same kind as Homo sapiens or not?
His last response on that matter within this thread was that it's "a stupid question." Fair enough--no reason to expect Blast's "kinds" concept to actually help us understand the observable world. That would be, as Dembski says, a "pathetic level of detail."
Anton Mates · 10 March 2006
Lest I sound like I'm on vendetta because the guy killed my dog, though, let me mention again that Blast did point out the probable error in the paper's reported dilution rate. Props to him for that.
Steviepinhead · 10 March 2006
Yeah. We should definitely give credit when credit is due:
Just because he takes completely idiotic positions, does not mean that Blast is a complete idiot.
Necessarily.
Though Lenny has several very creditable arguments that go the other way.
BlastfromthePast · 10 March 2006
Anton, if you live in southern California, come by and I'll show you my degree.
There's another mistake in the paper--somewhat trivial, but there nonetheless.
He says that the ratio of mother cell membranes counted to the number of unicells is 1:4. He then says this means that 75% of the time there are two daughter cells, and 25% of the time there are four daughter cells. Write an equation for that, and there's no solution except the trivial solution of zero. He should have said that '75% of the time the mother cell divides into four daughter cells, and that 25% of the time it divides into 8 daughter cells. The ratio then works out.
Anton, you have to understand that for me the Theory of Evolution is SO wrong that I have absolutely no motivation to learn it properly. Plus, when I say something, I'm giving the gist of an idea. I don't plan on publishing what I write here, so the only thing that matters is the basic idea. And, yes, maybe I make it a bit difficult for you; but I guess I'm assuming you can get to the gist. Maybe that's unfair on my part. But as I'm sure you know, we do have other things to do in life, and we can't always take the time to get all the details right.
As to the 1.68, I misunderstood that as days/generation, rather than what it really is, generations/day, which Vicklund correctly points out is a little more than 14 hours per generation. The reason that they say 10-20 generations is that when there are multiple forms present in the culture variable growth rates can occur, with one form reproducing faster than another. So the authors were just hedging--which makes the range understandable.
One last go-round: if we take the 10 days--we're told that even 100+-cells were present then--and subtract the 5 days (which is when my intuition tells me the signal should be felt), that leaves 5 days. This translates into 8 generations. 2^8th power is 256. So the 'initial' density of the 'variant' would be something like 1/500th (due to differential densities) or 1/1000th (also taking into account an additional day of reproduction) of the 0.1% 'grazed down' density of the 'unicells'. I still think the numbers work out suggesting that "if" the 'variant' were there originally, that it would have somewhere, at sometime, been detected.
But, I think we've beaten this thing to death. And we all probably need a rest.
I hope somebody pursues this experiment.
Oh, BTW, when I wrote "slowly dissolving", I was quoting by memory. I think they actually say the 'colonies' "slowly decline", or something like that.
Anton Mates · 11 March 2006
PvM · 11 March 2006
W. Kevin Vicklund · 11 March 2006
Russell · 11 March 2006
Anton Mates · 11 March 2006
BlastfromthePast · 12 March 2006
PvM · 12 March 2006
PvM · 12 March 2006
PvM · 12 March 2006
Anton Mates · 12 March 2006
BlastfromthePast · 14 March 2006
Steviepinhead · 14 March 2006
PvM · 15 March 2006
PvM · 15 March 2006
W. Kevin Vicklund · 15 March 2006
Anton Mates · 15 March 2006
Anton Mates · 15 March 2006
Oh, but before I do anything else--Kevin & Blast, you were right (as was Boxhorn, unsurprisingly) and I was wrong. No ln(2) in the formula for (predatorless) steady-state generation time. If the total population was literally increasing exponentially, you'd need that factor, but it's unnecessary here. So Kevin's estimate of 14 hours should be on the money. (But, as previously noted, that generation time will be shorter for any approximate steady-state in the presence of a predator, as was the case with Chlorella after the flagellate's introduction.)
David Wilson · 15 March 2006
W. Kevin Vicklund · 15 March 2006
Well, it's a good thing I previewed. It changes my post a bit.
I have modified blast's definitions slightly for accuracy and convention.
A = amount of Chlorella cells
w = amount of cells being washed out
g = amount of cells being grazed
k = doubling rate
w' = rate of cells being washed out
g' = rate of cells being grazed
F = flow rate
What we should find is that terms on the left should either be all linear or all exponential. So we should see
Aekt-wew't-geg't=F
or something like that if it were exponential. This is a simplification of the real equation, which I have yet to derive, so it is not necessarily correct. The actual underlying equations are a set of four linked differential equations, one for the flow and one for each of the populations, that must be solved simultaneously. Not the easiest task in the world, no?
Anyway, unless people really want to see four complicated differential equations solved simultaneously, I think we can call the point moot. The take-home is that for steady-state only the generation time is inversely proportional to the growth rate (whether or not ln(2) is included, it is still inversely proportional), and the growth rate is equal to the flow rate (in non-predator chemostats) or greater than the flow rate (in predator chemostats). During the initial stages of the experiment (once the predator is introduced), the growth rate will exceed the flow rate, which means the generation time of the unicells will be less than the steady-state value of 14 hours during the first 20 days. The data I have seen from googling suggests the maximum possible doubling time for Chlorella is somewhere around 8 to 9 hours.
Anton Mates · 15 March 2006
BlastfromthePast · 16 March 2006
PvM · 16 March 2006
BlastfromthePast · 16 March 2006
PvM · 16 March 2006
BlastfromthePast · 16 March 2006
BlastfromthePast · 16 March 2006
BlastfromthePast · 16 March 2006
BlastfromthePast · 16 March 2006
PvM · 16 March 2006
David Wilson · 16 March 2006
BlastfromthePast · 16 March 2006
W. Kevin Vicklund · 16 March 2006
BlastfromthePast · 17 March 2006
Anton Mates · 17 March 2006
OK, so what quantities are we finding formulas for?
Since the objective here is (so far as I know) to determine generation times, it makes sense to look at B(t), the number of Chlorella cells (or colonies, whichever morph interests you) produced by time t. Consider also D(t), the number of cells which have been lost to death or washout between times 0 and t. So B(0) is your initial population size, D(0) = 0, and your population size at any time is B(t) - D(t). The generation time TG(t) is the time it takes for the population, starting at time t, to produce a number of cells equal to its own size (at time t):
B(t+TG)-B(t)= B(t)-D(t).
As indicated, TG(t) could vary with time (though fortunately it doesn't for the cases considered.)
What quantities can be taken as constant? The dilution rate k, measured (say) as a fraction of total chemostat volume per unit time, and the maximum Chlorella growth rate K. Of course k ≤ K or else the Chlorella washes out completely.
What else is good to include; probably P(t), the number of Chlorella cells specifically lost to predation. P'(t) is at least roughly constant in a steady-state situation, but in general varies all over the place. Of course it's never negative.
In a predatorless steady state, cells are lost only by medium dilution, so the rate of loss is the product of the dilution rate and the current population size: D'(t)=k*(B(t)-D(t)). By assumption of steady state,
D'(t)=B'(t)
so that the population's rate of change (B'(t)-D'(t)) is zero and the pop. size remains at B(0) for all time. Thus
B'(t)=k*B(0)
B(t) = k*B(0)*[t+1]
Then TG, the generation time, is simply 1/k, as shown by the following:
B(t+TG)-B(t)=k*B(0)*[(t+TG+1) - (t+1)]=B(0)
k*TG=1.
In a predator-present well-grazed steady state, cells are lost by medium dilution at the previous fractional rate, but also to predation:
D'(t)=k*(B(t)-D(t))-P'. (Assume P' is constant since it's a steady state.) Again, the population is always B(0), and B'(t)=D'(t). So
B(t)=k*B(0)[t+1]+P'*t. Then
TG = 1/[k + P'/B(0)].
Note that, as Kevin said, TG is smaller now. In fact, it's probably equal to 1/K; the severely-reduced Chlorella population no longer has overcrowding and nutrient competition slowing down its growth, and will therefore grow at its maximum rate K. (This requires "fine tuning" of the predation rate so that P' = (K-k)*B(0), but that should occur automatically by assumption of steady state. If the predation rate is slower or faster, the populations will adjust to correct it.)
In an exponentially-growing transient state, as occurs at the start of the culture or after each population crash, the predation rate (if there's predators at all) is small enough to be neglible compared to the loss from medium dilution, and the Chlorella will grow at its maximum rate K. Therefore
B'(t)=K*[B(t)-D(t)] and
D'(t)=k*[B(t)-D(t)];
the total population size is B(0)*exp([K-k]*t), so
B(t)=B(0)*[K*exp([K-k]*t)-k]/[K-k]. Then TG is ln(2-[k/K])/[K-k].
In a state of exponential population crash, the generation time is virtually infinite, simply because the total number of Chlorella that will ever be produced converges to a finite number. Or, more realistically, the population will stop crashing and start doing something else before a generation's elapsed.
So, to summarize and plug in the (corrected) dilution rate and Chlorella's max growth rate as estimated by Kevin: Generation times will be about 14 hours for unicells in steady state without predators, about 9 hours for unicells in steady state with predators, about 8 hours for unicells whose population is recovering exponentially, and effectively infinite for unicells experiencing population crashes.
Of course none of these are valid over the long term when you've got predator-prey oscillations and whatnot, as just before the colonial morphs appear; to calculate that you'd need much more info than we have (such as the Ochromonas predation success rate as a function of the densities of the various organisms) in order to solve the interdependent differential equations describing the various populations over time.
W. Kevin Vicklund · 17 March 2006
For the sake of completeness, we should also note the growth rate of colonies and predators in steady-state is the flow rate, or a generation time of 14 hours for each in steady-state. This is assuming the unicell population is also at steady-state and not fluctuating, of course.
David Wilson · 18 March 2006
'Rev Dr' Lenny Flank · 18 March 2006
PvM · 18 March 2006
I'd like to hear Blast explain why Darwin was wrong about varieties and incipient species? And why should we rely on Denton whose book seems in many aspects to be quite flawed.
BlastfromthePast · 20 March 2006
BlastfromthePast · 20 March 2006
BlastfromthePast · 20 March 2006
Finally, the derivations of Anton and David Wilson both look fairly good.
I've looked at some papers on mixed species chemostats that deal with the mathematics, and they're quite complicated. I think your equations, though simplified, are helpful. (Maybe I should say that BECAUSE they are simplified, they're helpful--a compliment.)
PvM · 20 March 2006
PvM · 20 March 2006
And note how Blast seems to ignore the other reasons given why the authors reject the induction hypothesis. Somehow Blast took one, called it the 'principal reason' and avoids dealing with the overall reasons presented.
Irrefutable indeed...
Sir_Toejam · 21 March 2006
Pim-
you do of course, realize that your simply feeding his delusions by the simple act of responding to them, yes?
The one thing I'll give Blast over Larry is that he rarely spreads himself to other threads once focused on a particular non-issue.
logic levels are about the same, tho.
k.e. · 21 March 2006
Careful Blast you are only a few day away.
APRIL FOOL, n. The March fool with another month added to his folly.**
Why is it whenever the noose tightens you project ?
Evolutionist this...... evolutionist that.
Your absolute classic was
DarwinistsCreationists have been denyingcreationismevolution for 150 years.Why align yourself with such an intellectually vapid and sine nobilis bunch of cultural miscreants ?
A fringe group of knowledge pygmy's ?
Uneducated cultural slobs who think religion IS culture. ?
Frightened that their hold on reality as described to them around 5 years old was just an elaborate fantasy.
Wasting their lives and those of others justifying the unjustifiable.
Your should start your own eduKational intuition Blast , you have no need of knowledge.
BlastfromthePast · 21 March 2006
The fact that two 'taxa' of Chlorella have been shown to actually be Scenedesmus, which is known to form a 8-cell colonial form through chemical induction, doesn't seem to slow you down one bit, does it? Just pretend I never pointed it out.
Good-bye, Panda's Thumb.
W. Kevin Vicklund · 21 March 2006
W. Kevin Vicklund · 21 March 2006
Anton Mates · 26 March 2006
Jason · 19 April 2006
Jebus! I can't believe this crap went on for a month or more!
Will someone please explain to me how, if the Chlorella were becoming a new species, did it become the same species over and over again?
IOW, when the single-celled species was put under the same pressures, it rapidly evolved into a brand new species, and did it repeatedly 70% of the time.
Is this an accurate description of what happened, in your opinion?
W. Kevin Vicklund · 19 April 2006
First, I don't know if the differences are enough to truly classify it as a separate species. It's one of those fuzzy areas in biology when it comes to these types of critters.
Secondly, we haven't determined whether this is a series of identical (or similar) mutation events that has arisen in most of the experiments, or if this is a persistent subpopulation that is below detection levels. The data as given supports both hypotheses. If the first, it would indicate that the mutation leading to colony formation is quite easy to obtain, which to me points to either a single point mutation or the wild-state being unstable but highly selected (ie multiple sites where a mutation can lead to colony formation). I think I'd favor the unstable explanation, as it better explains the multitude of colony sizes at first.
Anton Mates · 20 April 2006