When micro = macro ...

Is a chihuahua able to breed with a great dane without human intervention to produce viable young? I would expect not given the morphological differences between the two breeds, but I honestly don't know. If not, then using the typical definition of a species- able to breed and produce fertile young- we have made something akin to a ring species. "Dog" is no longer completely sufficient as a species description.

According to Wikipedia rodents lack canines so I suspect the arguments would be short lived

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I wish I didn't know now what I didn't know then

Annafan,I'm curious, in your post you refer often to "fuzzy boundaries". Do you mean this in the sense of non-linear genetic expression (like that of pleitropy), or does the term take effect when you contrast genetic reality with our comfortable definitions in textbooks? Then, to loop around to the discussion topic, do you see micro and macro as human constructs, or as an actual seperate process?Merci,
Theus

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Veri Omni Veritas

Paleontology has a similar problem with reptiles. Based on phylogeny, all mammals and birds are still reptiles, because in a very exact manner our ancestors overlap with those in class reptilia. This is a much more dramatic example of the same problem discussed in your Seagull example.The simplist answer is that the descendents are, in a genetic sense, still reptiles and seagulls. But this says nothing about the ancestors or descendents, instead it weakens the origional terms of reptiles and seagulls. They are benchmarks, slang terms given to animals based on the most obvious characteristics. They have completely different meanings in science and social contexts. This has yet to be resolved, because the theory of evolution is younger than the nomenclature system it uses.Good point, but it has more to do with human understanding than it does with evolution. If you follow that train of logic, you'll see alot of the difficulties and misunderstanding scientists now have with the systematics of descent.Vale,
Theus

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Veri Omni Veritas

This is a bit of a tangient on the same issue as ring species.It's possible for animals which are essentially genetically identical to be unable to reproduce naturally.The best example I've seen of this is jumping spiders. There are hundreds of different kinds of jumping spiders. If you were able to mechanically force them to mate, the offspring would be viable. However, the intricate mating dance that the spiders use in courtship don't match up. As a result, Spider A can't mate with Spider B, even though they are essentially the same species.This just goes to show how little has to change to split one group off from another and start them down the road of speciation

Which is why I try to think it amphibiously first. The rest bubbles out the developmental Mendelian BIONOMIAL.

Theus,I use the "fuzzy boundaries" in the sense that they aren't really objectively there, but overlayed by the observer (us) because of our tendency to categorize. (specifically when talking about the differences over time in one evolutionary line). And along the same lines, I consider micro and macro human constructs.But the topic was started more like a *question* to see whether this was the right way to look at it. I myself have no relevant expertise in these matters

Exactly what I was trying to say with the "dogs & aliens" reply.

This topic has come up in another thread about the literal truth of the Bible. Since it's a bit off-topic there, I'll post my reasoning on the subject here.To me, the seperation of micro- and macro-evolution is no based on fact. Apparently we all agree that small, tiny changes happen from generation to generation, as evidenced by countless examples, the best of which may be dog breeds.But if we all agree that small changes occur, what mechanism prevents those small changes from continuing until a new species is formed? If each generation the genetic code changes by 0.0001% through random mutation, genetic drift, or any other method, then would not the difference between one creature and it's progeny 100,000 generation removed by so significant that we would call it an entirely different species?The seperation here seems to be a Creationis construction to be able to accept "variation within kinds" while still denying that new species form from old. There is no mechanism proposed to stop the changes and falsify macro-evolution. There is no real definition of "kinds," either. It has been proposed in another thread that the biodiversity we have today may be the offspring of just 2000 progenitor animals (so 1000 "kinds"). Is the definition of "kind" a family, or genus? That really wouldn't falsify the evolution of new species from old, as we see thousands of species within the same family or genus, and the majority cannot interbreed (if we are to use such a simple definition of species as "two organisms that cannot interbreed and produce viable offspring"). How does this not demonstrate the arisal of new species from old?Ana nalogy to the micro/macro seperation would be a car driving on the highway. The car can move along the highway within its own state, but is somehow prevented from crossing a state border.Obviously this is rediculous without some mechanism that prevents the car from crossing state lines.To return this to the micro/macro discussion, what mechanism prevents small changes from adding up to big ones? What prevents micro-evolution from actually being macro-evolution on a short timescale?To assume that one is possible but not the other without any such mechanism is folly - it is assumption based on a preconceived worldview, nothing more.

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Every time a fundy breaks the laws of thermodynamics, Schroedinger probably kills his cat.

with macrothermodyanmics that seperates inertial structure and force fields.Here is how Weyl put it, p 278 Physics and Biology in PHILOSOPHY OF MATHEMATICS AND nATURAL SCIENCE

quote:

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There are several methods for estimating size and molecular weight of a gene. Most of the radiation experiments are concerned with mutations called recessive lethals. A certain high percentage of these is due to an ionization depriving the gene of its reproductive power (while others are brought about by gross structure mutations). It is plausible to put the first kind of lethals in analogy to the inactivation of enzymes and viruses. For these latter processess, which are also due to single ionizations, one can determine the target size, either by means of the absolute dose of X-rays or by the relative efficiency o fthe various radiations. One finds target radii that are between one and five times as small as the radius of the enzyme molecule or the virus. Hence the target size of a gene for the totality of recessive lethal mutations 'of the first kind' ought not be much smaller than the size of a gene.

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This exploration towards the properties that block or do not is because

quote:

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These facts suggest that a gene is a (nucleo-protein) molecule of highly complicated structure, that a mutation consists in a chemical change of this molecule brought about by the effect of an ionization on the bonding electrons, and that thus allele genes are essentially isomeric molecules. The most elementary chemical changes which quantum physics can devise are localized two-step quantum jumps - first the molecule is lifted from an energy level 1 to a higher level 2, and from there it drops to a new stable state of energy level 3. The difference of 2 minus 1 is the necessary activation energy U. The rate at which a specific quantum jump requiring the activation energy U occurs spontaneously at a given temperature depends essentially on U alone, but varies extremely strongly with U (according to an exponential law). At the temperature at present prevailing on earth's surface such quantum junps as correspond to values of U between 1.4 and 1.7 would be occasionally occurring yet rare events...Thus one is tempted to complete the picture by interpreting mutation as a rare quantum jump with an activation energy within the range just mentioned (Delbruck's model).

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p278Nanotechies might think that can simply cut and paste out these target regions. If they do we will be able to have the material if not the info on what might prevent some degrees of changes.This message has been edited by Brad McFall, 09-07-2005 03:37 PM

Brad, I'm not sure exactly what your argument is here.The exerpts you've cited seem to discuss the reasons mutations are rare events. Interesting stuff, but I'm not sure how this is relevant. Nobody I've seen claims that mutations are actually statistically common, or that every mutation (or even most) is replicated in the offspring.Part of your post seems to deal with mutations that do not survive the reproduction process - they are non-starters. That's fine, but I don't see any connection to some "barrier" that prevents new species from forming.Perhaps you could elaborate? I'm honestly not even sure if you are agreeing or disagreeing with me. Was your intention simply to provide background info regarding the causes of mutations, and why some of them do not survive reproduction?

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Every time a fundy breaks the laws of thermodynamics, Schroedinger probably kills his cat.

Sometimes I am not either agreeing or disagreeing.You wanted to know about what might enable one to find what stops changes from macro forming as if macro does not exist rethorically. It doesnt matter to me if this question is what micro changes lead to actual bradytelic populations or simply creates diversity instead.First the VOLUME of the changes has to be ID'D. I quoted Weyl to the effect of justifiying that such a cut is actually possible. Someone might think that even this is in question. I didnt think it was. that is why I responded.Once one has the volumes of this nature cut out of tissue one would need to apply the continuous nature of macrothermodynmics to the logically questionably split synthetic categories I labeled "inertial structure" and "force-fields" and the difference of cooridnation systematically and gravity would force the regressioin of the data into a line that falls in a light cone but yet due to symmetry enables the boundaries to be findable if enough numbers of these volumes were compared geometrically. The metric built from such a study would provide a sort of seive from which with the appropriate test if there are physical things that keep macroevo from happening in any clade to be not extinct would be findable and given enough dillegence found.It might be that the nature of the relation of ionization level and shape of the metric is causal for the correlation etc but these are things that happen as one refines a given means to cut out the volume. Get the volume. Find its properties (such things as its thermostat) and one will be well on one's way to a real answer. I guess this will be great if it happens in 100yrs. Today given Iraq and NewOrleans I have no confidence even in that estimate of time.The barrier is physical if it exists. One needs a method to count up these physical things where the barrier could be manifest first. I see no way by trying to relate correlations of forms extant vs extinct or with a likely hood of not surviving. That seems to be, in response, how you thought about it.We need to find the space of gene, in all its changable aspects. What I call a gene and Weyl called as one may not be the same descriptors but they would be functionally equivalent.I didnt mean to be obtuse. I just have to keep my thoughts in order. If you think that this still is not clear enough please let me know. I always respond. so far...This message has been edited by Brad McFall, 09-07-2005 04:18 PM

That's a lot better Brad, thanks for elaborating. It looks like we agree, you are just proposing a method by which the supposed barrier, if it exists, could be found.

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Every time a fundy breaks the laws of thermodynamics, Schroedinger probably kills his cat.

Yep, pretty much.