How many generations does speciation take?

But Saint Bernards and Chihuahuas cannot. (And I'm not entirely sure that a wolf and a pug could successfully reproduce.) One, basically. A single mutation can result in reproductively incompatibility.Ernst Mayr references (in What Evolution Is) a single gene speciation that effects hormonal ratios in butterflies, causing premating reproductive isolation. I haven't been able to find the original research on this one, though - perhaps someone else has some info? Another example of premating isolation as the result of a single mutation was witnessed by researchers in a population of snails - snails with the mutation had the opposite shell chirality of the snails without, and their genitals couldn't line up for mating. (I don't think it has been reported yet if the alleles have been fixed into separate extant breeding populations, so I don't know if true speciation has occurred.)An example of postmating speciation that comes to mind is the Robertsonian chromosomal fusions in wild mice (I believe a substantial body of work has been done characterizing these reproductively isolated populations in the Alps). The fusions cause chromosomal sorting problems if a mouse with a particular fusion mates with a mouse without the same fusion - most of the resulting offspring exhibit aneuploidy and don't survive, or have developmental defects. Thus this could serve as an example of single-mutation postmating reproductive isolation.Now, these mutations/reproductive incompatibilites arise in a single generation, but it may take several generations for fixation into separate populations.If a dominant, reproductively isolating mutation arose and segregated 50/50 in a single large birth group (like a brood of fish with several hundred individuals; or maybe those butterflies Ernst mentioned), then speciation could essentially occur in a single generation.

This is a good answer, yet I still hear you saying "we know that evolution occurs, but we can't actually predict when it will occur, how it will occur, why it doesn't occur when, where, or how we expect it to, etc."You can see how some might find that explanation eerily similar to creation arguments about why god designed things this way or that way, don't you?Even with our limited knowledge of climatology we have enough data to make predictions that bear out. I think it is reasonable to expect us to come up with reasonable parameters about how long it SHOULD take to achieve speciation. I'm getting sick of that map phrase (no offense - but I swear I've read it about fifty times in the last week or so), and ultimately it smacks of a bit of a cop out. Sometimes a simple "we just don't know" is the most honest and accurate answer. Platitudes are rarely satisfying - how many religious platitudes do evos find solace in?I read "the map is not the territory" and I hear "that's just the will of god" echoing in my head.Folly to attempt simple speciation models? Probably. Yet in pursuing this folly I hope to at least get a better understanding of things. Yet in this type of foolishness, I find myself in good company: the scientists and thinkers who look for impossible answers to impossible questions.

Cannot? Or do not? If you inseminated a Saint Bernard bitch with Chihuahua semen no viable offspring would be produced?

The same thing in terms of biological species. You've simply asked if the reproductive isolation is postmating or premating. Either way it is still reproductive isolation. The biological species concept you have been using includes premating isolation (as in the first two of the three examples I gave in my previous post).If the only way two populations can/will reproduce is by human transfer of semen, then those two populations are not the same species by the BSC definition.

Loudmouth's view is not anything like creationism, not even if we all sat with Queztal's dog looking for salamanders on islands in the middle of LAKE erie. Mine is.Since you moved on before I could even paste and click here's the raw- ill be editing in real time so dont expect this to be the final view.Lets look at it in terms #sequence genes copies before speciation duplication =gene duplication separations. And then see how many generations that was. Yes I did get it LM. In fact that was somewhat thepoint I was mak’n in thegrey alien thread when I synthesized some physics into my idea on how this thing works.
The definitions to use are Biological sequence analysis defs p 160
7.1 The tree of life
The similarity of molecular mechanisms of the organisms that have been studied strongly suggests that all organisms on Earth had a common ancestry. Thus any set of species is related, and this relationship is called a phylogeny. Usually the relationship can be represented by a phylogenetic tree. The task of phylogenetics is to infer this tree from observations upon the existing organisms.
Traditionally, morphological characters (both from living and fossilized organisms) have been used for inferring phylogenies. Zuckerandl and Pauling’s pioneering paper [1962] showed that molecular sequences provide sets of characters that can carry a large amount of information. If we have a set of sequences from different species, therefore, we may be able to use them to infer a likely phylogeny of the species in question. This assumes that the sequences have descended from some common ancestral gene in a common ancestral species.
The widespread occurrence of gene duplication means that the foregoing assumption needs to be checked carefully. The phlylogenetic tree of a group of sequences does not necessarily reflect the phyogenetic tree of the host species, because gene duplication is another mechanism, in addition to speciation, by which two sequences can be separated and diverge from a common ancestor. Genes which diverged because of speciation are called orthologues. Genes which diverged by gene duplication are called paralogues. If we are interested in inferring thephylogentic tree of the species carrying the genes, we mustuse orthologous sequences. But, of course, we might be interested in the phylogeny of duplication events, in which case we might construct a phlylogeny of paralogues, even the paralogues within a single species. The distinctionbetween paralogues and orhtologues is illustrated by Fig7.1Thus while it would predict a number of generations I think that better would be to do the maths with Wright’s diagram I will search out and extend this to my discussion of physics. Instead of getting that far into the actual work. It will be MUCH easier to use IN HOMOLOGY Loudmouths’ relation of analogue and digital to partition the variance in sequence Convergence per monoplyetic suspect. There are people here who wish to argue that in the end it is all digital. Let us please leave that till we come to terms about QM in the whole things, if you wish to address what I am saying specifically following up Loudmouth’s post.Looking at figure 7.1 lets assume the ortholgous tree was constructed by any systematic means, creationist or evolutionary and the paralgous one by any means of separating molecular differences. What I noticed was likely a mistake in science (you are free to argue the digital divide of what I am saying but I am not getting there yet) was that as QM took over the better philosophers of science the possibility of a simple Gibbs classical equilibrium binding the material particulate genetic reality seemed to be passed generation by generation of learning students by. Thus I am showing how to use an homologous series under Gladyshev’s law can bind the branching similarity in the trees as diagramed from information on two differenent levels (genes,species) and PREDICT the # of generations.We approach this from Russel’s viewpoint.Bertrand Russell The Analysis of Matter p 252

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Take first the relation between the space of physics and the space of perception. Within the private space of one percipient, there is a distinction between perceived space-relations and inferred ones. There is a space into which all the percepts of one person fit, but this a constructed space, the construction being achieved during the first months of life. But there are also perceived space-relations, most obviously most obviously among visual percepts. These space-relations are not identical with those which physics assumes among the corresponding physical objects, but they have a certain kind of correspondence with those relations. If we represent the position, for physics, of visible objects by polar co-ordinates, taking the percipient as origin, the two angular co-ordinates correspond to perceived relations among visual percepts, while the radius vector (except possibly for very small distances) is inferred by means of causal laws. Let us confine ourselves to the angular co-ordinates. My point is that the relations which physics assumes in assigning angular co-ordinates are not identical with those which we perceive in the visual field, but merely correspond with them in a manner which preserves their logical (mathematical) properties.

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The calculation proceed by using LONDON forces believed to be involved in adsorbtion and to vary with distance by the seventh power but a simple Bayesian probabilism is not suffient but to get some replication and reproduction. The whole randomized program must also work out in the vocabulary of Hilbert how Russel’s percipient center is but a point of a space curve as the plane of angularity is sphericalized. If the Baysian probabilities still work for the volume rather than the plane in uniting the form of the para and otho bushes an analogue view of speciation is retained no matter what the digitial information is carried by any other sophisticated decomposition of the sequence data.ADDTION VOCABULARY NEEDED from Geometry and the Imagination by D. HIlbert and S.Cohn-Vossen Chelsia Publishing Company New York.1952 page178-182 "Most of the discussion of the last section can be adapted to apply to curves in space (sometimes called twisted curves). To start with,...we shall try to find a plane lying as close to the curve as possible in the neightborhood of the point under consideration. To this end, we draw the plane...In this process the plane approaches a limiting position. The limiting plane satisfies our requirement; it is called an osculating plane of the cureve at the point under consideration..We shall next extend the concept of curvature to space cureves...called the polar axis of the curve at the point underconsideration."
The angular Russel "physics" gives the plane in various orientations. I asserted it will format a sphere with the same probability space. This is not a space of any digitality! There will be a group theory of the answer as well, mathematically. The "curve" is the point where 1-D symmetry (CODED) effects are confused in space. OK its better I stop explaining in my "future" lingo to try to get someone interested and just sit back and start to do more of the work myself.I had told Para that EVC must wait. I guess I prematurely started this one thinking that there would be a larger dynamic. I knew Loudmouth would come back and question me but seeing that it would just be one on one between us its not going to work any better for evc than what has gone on before between us. I have just started to build a working Java program. I do not need to divide where a biologist with QM training might refer. If the only point is to gain a streght of evoluionary mindset one does not need the detailed model. I will probably be arguing the whole history of physics but I see now in real time that its not time for this level of detail as of yet.What looks really exicting is that one is not limited to Lewontin's two evolutionary consequences depending on the "original genetic composotion" in terms OF TWO different molecular genetic approaches which will ALWAYS be the polar coordinates in this model and exist with a digitial approach only that I dont agree to work on. That is possible but if the LONDON force, the two types of 1-D symmetry and the 4 bases, lead to a predictable PRIOR POSTERIOR PROBABILITY it might be possible to affirm creationist claims that have most change on the order of only a few decades generations only.THE REASON it is exciting contra what else we hear here is that space drops off with r^2 but the bases quad to that atomically thus circumscribe confused relations in series beyond 7 bases which if molecualarly have electron phase harmonies in the same places could work purely by formal DECODING of a relation between ortho and para by a homo series obeying macrothermo as in the data in fig7.1 cited above. Sorry if you all dont think in the same words as I do.I dont have the actual number yet. I know how I want to approach one.
The hard deductive part is to reduce with actual sequence data and trees to find the places of 8 base sequence streches as the single point in Hilbert's sense divided by Russel between the perception and physics of the mutation itself. Quite a project. It should give some range on generations from the data (to be used) and from that a generatlization about generation time in general would be foolish to express but would be possible. USING THAT will not make ID be the response. It raises science as a whole and permits alternatives at the same synthesis. When the day comes I convert other evcers is this day that c/e is not political. Oh how I yearn for the months of my teenage youth.This message has been edited by Brad McFall, 03-03-2005 16:40 AM

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This is a good answer, yet I still hear you saying "we know that evolution occurs, but we can't actually predict when it will occur, how it will occur, why it doesn't occur when, where, or how we expect it to, etc."

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You can see how some might find that explanation eerily similar to creation arguments about why god designed things this way or that way, don't you?

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Going back to the weather analogy, we know how storms are caused in principle. There is a mechanism that is known. The same is true in evolution. The mechanisms of mutation, selection, and speciation will cause bio-diversity in the same way that differential temperatures and pressures will cause storms. For the GodDidIt theories there is no mechanism that can be tested.

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Even with our limited knowledge of climatology we have enough data to make predictions that bear out. I think it is reasonable to expect us to come up with reasonable parameters about how long it SHOULD take to achieve speciation.

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In climatology we can make predictions, but they aren't that specific. For instance, no one can predict the temperature in NY city for December 21, 2015. Does that mean that we don't understand the mechanisms of climatology? Of course not. What SHOULD the temperature be on December 21, 2015? At best, between -100 and 100 degrees F. For speciation, we can come up with reasonable parameters but they will be as vague as weather predictions. In the short term, we can look at ring species and make very strong predictions on future speciation. We look at a stable ecological system and we can't make one simple prediction WRT speciation. We can predict that speciation will occur swiftly on an island that was previously barren. We can predict that speciation will occur less often in a stable ecology. I don't think we can make a simple "this many generations, this many species" prediction.

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I'm getting sick of that map phrase (no offense - but I swear I've read it about fifty times in the last week or so), and ultimately it smacks of a bit of a cop out. Sometimes a simple "we just don't know" is the most honest and accurate answer. Platitudes are rarely satisfying - how many religious platitudes do evos find solace in?

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I have read it quite a few times as well. Perhaps we should shrink it down to TMINTT to save space.I have always found the phrase to be instructive, a check on the reasoning behind a model. It reminds us that models should reflect reality, not the other way around. It is not a cop out. In fact it is quite the opposite. It a strong test of the logic behind the model.

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I read "the map is not the territory" and I hear "that's just the will of god" echoing in my head.

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I hear "all models are tentative and must adhere to reality". The voices in your head sound a lot more entertaining than mine do though.

Hypothetically, sure. How many biologists are willing to walk that narrow, swaying limb and say that this actually DOES occur. Plus, you still have to have a population of your new species. One reproductive anamoly does not a species make.(Ah, I see you make that point here:I'm more interested in 'what is likely' vs what is theoretically possible. Haldane took a stab at it, but seemed to get more criticism than anything else. I'm having difficulty finding similar research. Ahh the snails. This doesn't seem to meet the criteria I established in the OP - using the BSC definition of speciation, which would include artificial insemination.I know the BSC is restrictive, but I think it is the clearest way to show non-evolutionists that speciation, not hybridization and the odd mutation - actually occurs.In any case, I don't think the snails are a good example. As Wounded King pointed out (I'll look for the post) they could still reproduce through artificial insemination. An analogy would be a man who has a low sperm count (genetic) and can't produce viable offspring with his wife without artificial means. Is he really a member of a different species?[qspink]An example of postmating speciation that comes to mind is the Robertsonian chromosomal fusions in wild mice (I believe a substantial body of work has been done characterizing these reproductively isolated populations in the Alps). [/qs]Cool. I'll check this out. This could be exactly what I am looking for.As always, you provide good food for thought.

Great point. I would add that we know enough about climatology to predict the weather parameter for 2015 will be much narrower than that barring some superdupernino event.And that's what I'm looking for with are current knowledge of how evolution works - or how we THINK it works. How valid, or useful, is a theory that says "well a new species may or may not evolve in the next twenty thousand years." Crap, present that model to the Kansas School Board and ID will be part of the curriculum faster than boiled asparagus.We have lots and lots of information about evolution, I'm sure there have to be models out there that have been devised, or are being devised, that provide more insight into the frequency and likelihood of evolution than the weather in NY analogy. At least I hope so. That reminds me, I need to up my lithium dosage...

Not "hypothetically". One mutation can result in reproductive incompatibility. I gave examples. No, it doesn't. At least not the popular biological species concept put forth by Mayr and used by evolution scientists. There are countless species in the wild that have only a premating reproductive barrier, yet never mate - these would collapse into single species using your version of the BSC.In fact, some species barriers involving complete morphological genital incompatibility would fail under your definition.We could even extend insemination to in vitro fertilization; and collapse a bunch more species whose barrier is sperm-egg incompatibilities...It's all about reproductive isolation. It doesn't matter if it is pre- or post- mating isolation, it is still reproductive isolation. No, because MOST males and females of the human species are reproductively compatible. However, NO individuals among "chirality left" and "chirality right" snail populations are reproductively compatible. This is a huge difference - and why species are defined at population levels, and not at individual levels. Why yes, yes it does. That's all biological speciation is - reproductive incompatibility.

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And that's what I'm looking for with are current knowledge of how evolution works - or how we THINK it works. How valid, or useful, is a theory that says "well a new species may or may not evolve in the next twenty thousand years." Crap, present that model to the Kansas School Board and ID will be part of the curriculum faster than boiled asparagus.

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Yeah, that's the problem with presenting science to lay people. They hear about what science can't do and figure that science must be wrong. I don't mean to disparage the lay public, but many people are surprised when they hear scientists express doubt.Speciation depends on factors that are random, chaotic, and independent of one another (eg mutations, climactic changes, volcanic eruptions, tidal waves). You would have a better chance of winning a lottery than predicting mutations in one individual in the next generation. Natural selection also pushes species in two directions, one force pushes species towards stability while the other force pushes towards change. To trot out another worn phrase, future speciation is being controlled by the Butterfly Effect. One small change early in the process could have large ramifications further down the pipeline.I think this is a very interesting thought experiment, don't get me wrong. I'll try to get off of this "wet blanket" tirade and see if I can't contribute something towards constructing a model.

OK, I see where I'm miscommunicating. I think.(Using the talkorgins defintions) the BSC definition I'm using, which I think I stated in the OP, is: Yes, Dobzhansky modified his definition in 1942: The examples you've provided to meet the latter criteria, but that is not restrictive enough for me in this thread. I'm aware of the examples of speciation cited that meet looser criteria, but I don't think the stricter definition is at all unreasonable to use when one considers that evolution accounts for speciation from single celled organisms to multi-cellular plant and animal life.

Considering that speciation has been observed, I wouldn't say we'd have to wait that long: Observed Instances of Speciation
The article happens to also contain this bit relevant to my previous post (emphases mine): Neither description of the BSC includes human intervention as an exception.

I think this concept doesn't get much play with creos (or some of the evos even) here. This makes me think that a variable (for a much grander model than what I'm futzing about with) would be some sort population plateau where the sheer number of an existing species would prevent continued evolution because any and all new mutations are eventually cycled back into the population at large; then the mutations are simply watered down and exist in isolated pockets, or just die out.Once the species reaches a certain level, it would become extremely resistant to additional speciation because the baseline genes (for lack of a better phrase) would keep the overall species characteristics near the mean.I think this would be a sort of punctuated equilibrium argument, no?

Your definition is NOT the one promoted by TalkOrigins, rather it is a quote-mine, mistaken or not. It is taken from a passage describing the history of species concepts. I describe the accepted version of the BSC in my above post.

Do you honestly believe a Saint Bernard and a Chihuahua are seperate species simply because their reproductive organs don't fit together?You just can't rule out genetics and rely solely on morphology. Our current taxonomy overemphasized morphology and needs to be re-evaluated with more emphasis on genetics.Similarly, speciation solely as a result of geographic isolation is also incredibly weak. Europeans didn't encounter Australian aborigines until thousands of years later. Are caucasians and aborigines truly a seperate species?