I say no but why do evolutionists?
This is a sly way to demonstrate how unlikely evolutionism is on a probability curve.when on thinks of the millions (billions?) of segregated populations in biology(species) then it should be a high, or respectable percentage, are evolving as we speak to create new populations with new bodyplans to survive in some niche. By high I mean millions, with a allowance for mere hundreds of thousands. YET I am confident there is none evolving today. further i suspect evolutionists would say there is none evolving today. WHY? If not today what about yesterday or 300 years ago? Why couldn’t creationists say its not happening today because it never happened? Its accurate sampling of todays non evolution for predicting none in the past!
i think the only hope (hope?) is if evolutionism said , under pE influence, that all biology today is in the stasis stage and just waiting for a sudden need to change, qickly done, then stasis again. Yet why would it be that stasis has been reached so perfectly today relative to the enormous claim of the need in the past for evolutionism?
Anyways i think creationists have a good point here but willing to be corrected.
A couple of questions. How much difference would you say there was between our genotype and the genotype of our LUCA? Do you think that we have any cellular processes in common with our LUCA.
Or extinction, removing adaptations.
As opposed to the design narrative? What is the design narrative on how organisms react to a changing environment? Wait for the designer to do something?
Cause or side effect?
Dynamics which are required to produce higher levels of consciousness.
The base of the tree of life is thought to have beginnings that are less complex than any of the primal forms of the separate domains. Why should this be? Because if everything springs from the material then this speculation is logical. But what if this material outlook is false? There are other philosophies in which the base does not require simpler convergences.
Anyone who wants to know what genes can do on their own just needs to look at viruses.
Enormous differences, with a common scrambled core.
Just from a quick dig, an analysis of 147 sequences (2004, there are loads more now) they found fewer than 50 genes identifiably conserved. But there are all sorts of reasons for that, so it is likely to be a gross underestimate. By logic, DNA polymerase, and transcription/translation proteins and RNAs must be ancient, predating LUCA, along with chunks of metabolism and basic biosynthesis.
Look at any industry, motor, oil or whatever, and there will many different companies within it. There will be main companies and their sub-contractors, service companies, various manufacturing companies and such like all cooperating in a common aim. Is competition between companies the norm?
There is normally a hierarchy of positions within companies and less positions available the higher the pay grade. How much individual competition is there? I’d say quite a bit.
And the fruiting body of the fly agaric, and the pseudopodia of the amoeba, and the legs of a wasp …
Yeah, they don’t make their own DNA polymerase, or much else. Shrug. They don’t need to, they grab a cell that does it for them. Parasites are well known to have reduced genomes.
Here’s a fun fact: some transposons make a protein coat, even though they never go outside. Are these domesticated viruses, or viruses-in-the-making? What does holism tell us?
Yes. Assuming they occupy the same niche.
They still find common cause, by contrast to the separate vehicles themselves.
I am slowly working my way through your lengthy piece and so I’m getting a bit behind engaging with the ongoing arguments.
But through reading it I am getting a much better and deeper understanding of the processes involved in meiosis and mitosis. Processes which are both complex and intricately coordinated. An example I found while looking further into something that you had written is the way that the cell ensures the metaphase plate is precisely aligned centrally. I found the following articles: The equatorial position of the metaphase plate ensures symmetric cell divisions and Spatial Regulation of Kinetochore Microtubule Attachments by Destabilization The former begins:
Both make interesting reading.
This is just one example of how everything needs to happen in the right place at the right time for fidelity of cell division whether it is in mitosis or meiosis.
One thing I was wondering about and would appreciate an answer if you or anyone else knows. How do the chromosomes line up along the metaphase plate? Do they follow a particular order along the line or is it just a case of filling the nearest available gap? In humans that would be 23 positions. Also by what mechanism do they move to their position on the line?
Except when we don’t
Evolution is observed to have a direction. It is moving towards individual autonomy. The question remains as to why it took this direction. Did it just move away from the wall because it was the only way to go as in Gould. Or are we seeing a natural unfolding and condensation of consciousness to the level of the physical.
I’m not seeing that. Can you explain?
As far as I can tell, bacteria are autonomous, worms are autonomous, fungi are autonomous, grasses are autonomous.
Yes, some species such as homo sapiens depend more on cooperation within a society. I don’t see any move toward autonomy.
*Insert batshit crazy themed meme*
Quite. But I was talking of the competitive argument, that they produce soooo many more offspring than us.
In one sense, the cells of a body can be seen as a closer match to the numbers of bacteria. Counting organisms is misleading: count cells. One, or a few, cell lineages survives from a body, which is not far off what happens in bacterial populations over a similar time frame. Look at a chemostat, for example.
CharlieM,
The metaphase ‘plate’ is a notional locality rather than a physical structure. In a normal diploid state, each chromosome occupies a separate ‘territory’ in the nucleus, which may or may not have a functional role (I don’t know, rather than it isn’t known). During meiosis, homologous chromosomes ‘find’ each other, by partial sequence matching (a physical process!), while opposite poles of the cell give rise to spindle fibres which attach to the homologues. The metaphase plate is just the halfway point between the poles. I don’t think there’s any particular logic to how they line up, and which homologue goes to which pole is also random.
The spindle fibres contract, and the homologues are hauled apart. The process of ‘crossing-over’ helps ensure equal tensioning – without it, homologues may ‘stick together’ and both end up in one cell.
Both independent segregation and crossover give rise to the farthest-reaching consequences of sex. Most people think recombination is the reason sex arose, but I think it’s just an incidental consequence of cellular process.
CharlieM,
For sure, but I’d argue that we are seeing the tuned process now – tuned by evolution. To compete in the modern world, you have to be as good as everything else. To compete in a primitive world, you can get by with being primitive. You don’t need crossover to do a form of meiosis, for example, it just helps. You don’t really need anything other than the last few steps of mitosis, indeed, IMO, which you’ve already got if you’re not extinct. Evolution builds on the past, inevitably.
There is always a danger of labelling something as selfish because we don’t have all the facts. And although more is being discovered about the ins and outs of these processes, our knowledge is still very limited.
Many people thought that all non-coding DNA was junk and selfishly used up resources without contributing anything. But as our knowledge increased this was found to be false. IMO many of us are too quick to judge going on too little facts.
A misleading metaphor.
They are inherited from the mother cell. From A novel, dynein-independent mechanism focuses the endoplasmic reticulum around spindle poles in dividing Drosophila spermatocytes
That and much else besides is inherited from the mother cell. Chromatin doesn’t just consist of DNA. There is probably as much protein as DNA in chromosomes.
Copying is a process, it is a very complex activity within the cell. Genes do not spontaneously express themselves. Look at any cellular process whether it be gene expression, mitosis or meiosis and you will see thousands of nano beings pulling, pushing, transporting, assembling and disassembling all in a directed, purposeful manner.
To attribute the activity of copying to the gene in the way you do is like saying that it is your skeleton that holds you up and instigates your movements.
You’ve been around here long enough to know that’s not true. You simply believe that creationist lie because it fits your narrative, right?
And the fact that plants produce oxygen and we are constantly taking in oxygen that has been given out by plants: would you not call that a physical linkage? We all share the same atmosphere. Isn’t that a physical linkage? Or do liquids and gasses not count as they are too ephemeral and diaphanous whereas solids are reliably real?
Except when we are employed by the same company, then all is harmony 😉
It doesn’t persuade you. I know that. What about mycorrhizal connections in plants, forests interconnected by vast fungal networks? Would these be solid enough for you to count them as cohesive?
And the shared processes, what about them?
There’s no hard problem of consciousness for you. It’s all achievable through the magic of matter spontaneously springing into life. Arrange matter in a specific way and life will result. We don’t know how it happened but we promise you that’s the way it did happen. Consciousness comes about incidentally because the matter in living things is arranged in a certain way. We don’t know how it happened but we promise you that’s all there is to it.
The genetic code is not a program for building form. It is a collection of strings of nucleotides which need to be manipulated to produce complexes suitable for the organism. Manipulated by epigenetic marking, by packing and unpacking, by alternative splicing, by being brought into contact with other molecules, and by any other processes which I have overlooked or am unaware of. If you feel up to it, can you describe how eye colour (or any other trait that takes your fancy) is achieved via genetics? Run through the sequence of events from start to finish as you understand it.
Your “Celestial Gardener” gives a totally false impression of what I am saying. I am not positing some external force moulding and shaping nature. The creativity is within nature. We exist and have our lives within the life of nature in the same way that grapes exist and have their lives within the vine. A grape is meaningless without the reality of the vine, and our existence is meaningless without the reality of nature as a whole.
And how would you know this? Where do you get the knowledge to be able to definitively state that nature has not been subject to some sort of cyclic process over the purported billions of years of earth’s existence?
I am simply viewing them in context.
Good point. But my point is still valid although exaggerated.
And do you see any similarity between moons orbiting planets, planets orbiting stars and stars orbiting a galactic centre and electrons orbiting a nucleus? The whole reflected …
Charlie, if the orbit of earth around the sun was similar to an atomic orbital you’d be very unhappy. The whole is behaving completely different from the parts in this case.
Everything is in a state of transformation.
Heraclitus
Dying is within the living and living within the dying.
Transformations are more processes than single events and from what you write above you seem to be aware of this. The foetus ceases to exist as it is transformed into the new born baby, the baby ceases to exist when it is transformed into the infant and so on.
Older forms give rise to new forms at many levels. Theropods and birds have the egg laying, the bipedalism, a similar bone structure, and talons in common. But there is one important difference. Modern birds have developed traits which meant that they were less tied to the earth. The theropods that became extinct had well developed hind limbs at the expense of fore limbs which atrophied, they were relatively more massive. On the other hand birds developed specialised fore limbs, sophisticated temperature regulation and a reduced bulk and size. This freedom allowed them to prosper as the dinosaurs declined.
The most obvious analogues in multicellular life cycles are the transitional stages in the life cycles of insects and amphibians. The appearance of the frog spells the end for the tadpole. You believe that birds are transformed theropods. Well in relation to single organisms I am saying that a butterfly is a transformed caterpillar.
that still doesn’t answer the question about the origin of sex in eukaryotes in the first place.
Which species are you talking about that have eliminated males? I can only think of instances where males still are still produced only they may not feature in continuing the generations.
You seem to think that producing exact copies would be an advantage over producing variation. Which species do you think would be able to adapt better to changing conditions and progress further in evolution, those that engage in sex or those that produce clones by parthenogenesis?
I think nature is wiser than any single one of us.
No but without a regulatory network they are inert and harmless.
The thing is chromosomes and chromatids are living entities. As you sett so much store by physical attachment, when have you ever witnessed genomes apart from when they are attached to protein complexes. Genomes as considered by themselves are either an abstraction or they are dead molecules.
It does…you just have to have faith…the blind one 😉
Chromosomal crossover is a purposeful activity which ensures that a unique set of chromosomes will be passed to the next generation. You say yourself that it is a fundamental process. This process is a demonstrable example of the way that genomes are manipulated to achieve individual variation in populations.
Genomes are like multi-faceted ticker tape. They are pushed and pulled, wrapped and unwrapped, cut and rejoined, read and copied, and repaired.
The important point is knowing the actually facts, not on the philosophy of those who discovered them. And I don’t know the various philosophies on all those involved.
Analogies, analogies everywhere!
There are many parthenogenic species where males are extremely rare or not produced at all, especially in invertebrate groups. You’ll find examples in the wikipedia lemma I linked to previously.
Which species do you think would be able to colonize and spread more quickly in a habitat it is already adapted to? Those that have their genomes continuously scrambled by sexual reproduction and cannot reproduce without a partner or those that can instantly reproduce upon sexual maturation and rapidly produce faithful copies from a highly succesful genome?
Tsunami’s are harmless if you don’t live at the coast. Earthquakes are harmless if they occur on another planet. And guess what, parasites are harmless if no host is around.
Problem is: viruses are infectious. They will find a host with a “regulatory network” and multiply at the expense of said host. Sometimes that host will be you, and you will gain absolutely nothing from this involuntary encounter. Pathogens do not exist for our benefit. Why is that so hard to accept?
And sometimes they are completely eliminated by murderous chromosomes.
Drosophila limb development is a good area to study.
From this review:
When Goethe said of plants, “all is leaf”, he meant by this that all the structures stem from the same source but are transformed to serve different functions. A case in point is the human limb. Forelimbs spring from the same source as the lower limbs but they serve a higher purpose.
And we see the same process at work in insects. Antenna are transformed limbs. So it is no surprise that by interfering with development the growth of antenna we find there is a reversion back to limb development. Have they ever tried to induce antenna development where limbs normally grow? Would it be just as easy to do this? I’d be interested in any relevant references.
Andreas Suchantke talks about this. Here is an excerpt from a translation of his book:
The general archetypal form of these organs is physically expressed in a multitude of ways, the course of which can be altered by manipulating genetic networks.
Your ‘system’ is as much an abstraction as the genome. It exists only in your head, a model pieced together from diagrams in Sal Cordova posts … 😉 There’s something ‘real’ at the back of it, but then, the genome is real in the same sense.
Regardless, given an environment where genes (DNA/RNA) are copied, genes compete to be copied. But you’re never going to understand the point of the gene-centric view, no matter how often I explain it, and I’m not sympathetic to your rather waffly mysticism, so I’ll withdraw.
Worth mentioning that all such species have homologues of meiosis specific genes – their ancestors are always sexual. So something that can only form through sex shouldn’t be regarded as a blocker to its evolution.
There’s already something living there!
Asexuals can extend a range easily, because their close ecological competitor isn’t there. Their task is harder where the sexual species is present – and I’d quibble on the ‘highly successful’ part. Each snowflake sexual genome gets tested once. Taking an average genome and repeating it ad nauseam tests it more accurately, exposing it to selection in numbers, and in competition with the varied resident. It will never have a better allele at any locus than its sexual competitor.
Why? My ecology is a bit rusty, but I believe new habitats open up continuously because of disturbances and succession.
.. and colonization of a new habitat is more easy because parthenogens are not mate-limited.
If memory serves, parthenogenic species often have overlapping distributions with their sexual sister species. Hence, either competition isn’t that stiff, or is somehow avoided. Succesful parthenogens are more likely to come from sexual species with broad ecological niches and distributions, so there appears to be some safety in numbers. I suspect that the combination of generalist strategy with superior colonization capability is important in the persistence of parthenogenic lineages.
Yes, but it is inevitable that, where a parthenogenetic mutation occurs, there is a sexual species nearby.
For sure. Also, where dioecious, that 2-for-1 thing.
Hard to be sure which way the contest is going in a snapshot. But competition can’t be avoided, for ‘Malthusian’ reasons – intraspecific competition is what drives NS, after all (sort of …). And niche-competitive interspecific competition, which this is, would eventually result in competitive exclusion, a higher-taxon analogue of drift.
Given that it requires a mutation, then the bigger the sexual population, the more likely it is. But then, the bigger the population, the more variation there is, and the harder the parthenogen’s task in replacement, since it has no variation (rather, much less).
Their strategy is one taken at random from the sexual population and repeated. Certainly it will work where the sexual has no current presence – the need for mates creates a kind of ‘surface tension’ effect at its perimeter, limiting extension. But I take issue with ‘mystery of sex’ thinking in the expectation that parthenogens should defeat their parent species a sufficent amount of the time to create a puzzle as to why the latter are still around.
Parthenogens tend to have broader ranges and generalize to utilize broader niches, at least for the examples I am familiar with (haplodiploid arthropods). I guess that fits what you are claiming, and parthenogens simply avoid competition.
It doesn’t need to replace the sexual population (and I believe this doesn’t occur that often), it just needs to persist. Re. variation: you are assuming both populations start from a suboptimal situation and need to rapidly adapt. If this isn’t the case, then the larger variation in sexuals isn’t necessarily an advantage.
I haven’t argued for that. Rather, I have taken issue with the reverse claim that sexual species will purge asexual sister species because they can more rapidly adapt. This ignores the fact that sexual reproduction has significant drawbacks, i.e. mate-limitation and destruction of co-adapted allele combinations. Typically, the advantage of sex and recombination occurs when populations need to rapidly generate genotypic variation to deal with novel environmental challenges.
Or aren’t really up to it?
Yes, though there are obviously challenges to that. Muller’s ‘ratchet’ (coined, I believe, by our own Joe F), locus interference, the ‘red queen’ effect of a sexual biosphere, and my own favourite, gene conversion, which increases the expression of deleterious recessives.
That’s not quite the argument. A large population has local adaptation – eg the temperature-correlated clines in body size observed across numerous groups, where heritable. This gives a clone a harder task.
But the other issue relates to variation along the genome. If there is any fitness difference at any polymorphic locus, the asexual can have the ‘best’ variant, but it won’t have the best at every locus. It’s true of any given sexual individual too, but they are only tested once. Sexual populations are sorting at locus level; asexuals at full-genome. It doesn’t need an environmental change for a population to adapt; it just needs a beneficial mutation, and decoupling from other loci sure helps. I’m doubtful that there is any population which is not in the process of purging detriment and concentrating benefit (kinda the same thing) at any given moment. Asexuals start off on the back foot, and fall behind.
No, I don’t think that’s the whole story. It’s the whole sexual clade, and the deterioration of their own genomes, that gives the reason for the comparative rarity of parthenogens.
The latter is only a problem if they arose by some other means. If recombination/segregation cause co-adapted combinations to arise, there’s only a problem if they break more than they form. Which they don’t!
Such as competition from a novel parthenogen? 🤔
They still hang on, so I presume they went where the sexual species cannot follow 😉
This is something I can claim some expertise on, by virtue of having had an extremely knowledgeable roommate who studied exactly that. As I understand it, the main piece of evidence to support the claim that asexual lineages are evolutionary dead ends is the “twigginess” of asexual lineages on phylogenetic trees. This has been accepted as evidence that asexual lineages are short-lived, because of the reasons you mentioned above. My former colleague Tanja (Schwander) demonstrated that the observed phylogenetic distribution can be explained by factors that are independent of (mal)adaptive effects of reproductive mode. Hence, as far as I am aware, none of the challenges you mention have been observed to affect evolutionary persistence of asexual lineages. The paper is here. It touches on several topics we have been discussing.
It is a problem. Suppose that your model holds up: there are multiple subpopulations connected by gene flow (essentially the island model), each with locally adapted populations. Then the sexual populations are constantly required to cope with influx of maladaptive alleles. In such cases, recombination is a curse, as it prevents the sexual population from adapting to the local environment.
Why would that give them a fright? A new parthenogenic lineage is ecologically indistinguishable from its sexual compatriots, and if you are right it will only fall behind. 🙂
Well, clearly observed species exist! But it’s hard to determine if they are stable or on the way out.
None? Well, the neutral ones haven’t been ‘observed’ either (to sound like a Creationist!). It’s certainly interesting that neutral models can generate the pattern, but I wouldn’t consider that grounds for dismissal of the rest. It’s notable for instance that rotifers have notionally ‘haploid’ genomes, which could support the contention that gene conversion was an issue more typically. Once a genome has passed a threshold of divergence, it can’t be used for recombinational repair, so gene conversion stops and dominance effects stop masking beneficial recessives, making them a touch more evolutionarily flexible.
Another thought: the ‘geographical’ model would appear to support my contentions on competition – why are they in these poor habitats in the first place? ‘Cos they can’t compete! So, not all that neutral then!
A third thought: the ‘history’ section of the paper is stuffed with the ‘twofold cost’ stuff that I (an internet crank, I know) find completely misplaced as a ‘mystery of sex’ issue! It’s a ‘mystery of dioecy’, at best.
And yet it provides the locus-level ‘tuning’ that enables such local adaptation in the first place – and allows access to benefit segregating in the wider population, flowing in on the same tide. Nonrecombining genomes might be able to hold onto a beneficial combination, but there might be a better one just round the corner! Plus, that local adaptation they’ve conserved only helps them locally – stopping recombination doesn’t generate a broad scale benefit, at least on that model.
Competition ‘selects for’ alleles that deal better with that competition. The sexual can network these alleles at locus level, raising the fitness of the population. The asexual can’t access these alleles, if it doesn’t already have them, so its subpopulation fitness can’t keep pace.
So it is. As far as I know elevated extinction rates of asexual lineages have not been demonstrated. I also note that several long-term asexual lineages are known.
I wasn’t aware of that. interesting, thanks.
Haha, what happened to the “Malthusian reasons” and the severe intraspecific competition? The sexuals dedided to gang up on those pesky asexuals and drove them away? No, if there are no sexuals in those habitats, they either can’t reach them or they cannot survive there. In either case, the asexuals compete just fine.
I think you miss the significance: nonrecombining genomes can hold on to combinations of alleles. That is: they preserve association of beneficial alleles and beneficial epistatic interactions. Recombination destroys these.
ETA: Misread your comment, sorry. Yes, there may be better one, but if it arises it cannot be reliably transmitted in a sexual population that experiences constant influx of maladaptive alleles.
I was actually arguing the opposite: having recombination doesn’t generate a broad scale benefit on that model.
Yes, the Red Queen scenario. I won’t deny that sex brings certain benefits. I merely point out drawbacks exist as well. The balance between pros and cons will depend on details of ecology, population structure and such. I don’t see any reason to suppose that sexuals will always have the upper hand.
I’ve read some of it.
From what I can make out you believe that evolution is just the result of haploid genomes making copies of themselves. But the way I see it meiosis produces unique haploids not true copies. I’m sure we can both agree that present day humans with our 46 chromosomes have vastly different sets of genomes compared to our ancestors stretching back into the remote past.
What, just floating freely in some ocean or whatever?
As soon as it was discovered how close genetically we were to our nearest primate relatives it became obvious that our differences could not be accounted for by genes alone. It isn’t the genes that produce the differences it is the way in which they are manipulated.
So you agree with what I wrote above, that it’s not the genes but the way in which they are manipulated?
But there is never any point in which there exists bare genomes without the context of their accompanying protein coats within a cell and organism. The closest we see to this are viruses, but they remain inert without the context of cells.
Bare genomes are an abstraction, never observed in reality.
Reality is littered with opposites, good and evil, selfishness and altuism, growth and decay, expansion and contraction, chaos and order.
Life is a progression which steers a course between these opposites, but if they didn’t exist there would be no course to steer. There are many levels to consider and to progress at one level may take death and destruction at a lower level. Our hands could not form without massive death and destruction of individual cells. In fact we could not have any form of life as individuals without this constant cellular death and destruction.
Many of these viruses are brought about by us humans failing to consider the wider context of our actions. Metaphorically speaking nature doesn’t care about individuals, she marches on regardless of the death and suffering of individuals. And I don’t see any problem with using the “selfish” metaphor for these viruses, but they still need the cellular processes in order to replicate.
But none of that prevents us from marvelling at the complexities of the replication processes.
You have no problem self-identifying with a single celled zygote, but you are baffled by the idea that you were the gametes that fused to produce it? What causes this hard boundary I wonder?
You need to distinguish between the phenotype and the genotype. In this case, “the way in which they are manipulated” is a phenotype. What we are interested in is what part of the variation in “the way in which they are manipulated” gets inherited, because only that part contributes to resemblance between relatives (and ultimately between conspecifics)*. Genetics tells us that heritable variation is predominantly transmitted with the DNA.
ETA: *assuming a common environment