>I'm sure there is some subtle point I'm missing
>here because Stephen J. Gould was a rational
>fellow who devoted a life time of studying and
>investigating evolution and so is not likely to
>put forward an idea that seemingly runs counter
>to gradualism while having likely been
>aware of rather complete sets of fossils like
>that of the whale and its ancestor, horses, or
>from the therapsid reptiles to the mammals.

>Thus, if someone could shed some light on
>this point I would much appreciate it.

> No. But Gould never argued for saltation. In classical PE, transitions
> are gradual, with all the intermediates anyone would expect. In fact,
> the initial PE paper contained a claimed example of gradual change, in
> the evolution of Phacops trilobites. The claim is that such gradual
> changes are rare in the fossil record because they usually happen
> quickly in geological time, and in a restricted geographical area, such
> that we are unlikely to have a good series to show them.

> But let's suppose you are referring to a series showing gradual change
> on a geological time-scale, i.e. a smooth transition over millions of
> years. Would this disprove PE? Sure, in that one case. But Gould never
> (hmmm, better make that "seldom", just in case) claimed that PE was the
> sole means of speciation, just the predominant one. You need to assemble
> a whole bunch of transitions and see how many of them match gradualism
> (however you want to define that) and how many match PE.

> A bigger problem is that it's impossible to tell if one fossil species
> (really, a morphotype) is ancestral to another. An even bigger problem
> is that you can't really identify species in the fossil record, only
> morphotypes.

> > I'm sure there is some subtle point I'm missing
> > here because Stephen J. Gould was a rational
> > fellow who devoted a life time of studying and
> > investigating evolution and so is not likely to
> > put forward an idea that seemingly runs counter
> > to gradualism while having likely been
> > aware of rather complete sets of fossils like
> > that of the whale and its ancestor, horses, or
> > from the therapsid reptiles to the mammals.

> Gould would say that these series are not gradual transitions at the
> level of species. Instead they're a series of species showing a
> long-term trend. Nothing to do with PE vs. gradualism. Remember, PE is a
> theory about speciation.

> > Thus, if someone could shed some light on
> > this point I would much appreciate it.

> Sure.

> >I'm currently reading "What Evolution Is" by Ernst Mayr,
> >so far a great read, and I'm wondering about gradualism
> >vs' punctuated equilibrium; specifically, if we have
> >a set of fossils from one species to an ancestor
> >such that the transitional fossils that exist within
> >the set are such that it can be viewed as being
> >virtually continuous, then would this not
> >counter the claims of punctuated equilibrium?

> >I'm sure there is some subtle point I'm missing
> >here because Stephen J. Gould was a rational
> >fellow who devoted a life time of studying and
> >investigating evolution and so is not likely to
> >put forward an idea that seemingly runs counter
> >to gradualism while having likely been
> >aware of rather complete sets of fossils like
> >that of the whale and its ancestor, horses, or
> >from the therapsid reptiles to the mammals.

> >Thus, if someone could shed some light on
> >this point I would much appreciate it.

> Gould and, more properly, Eldredge, proposed punctuated equilibrium
> most specifically because of their familiarity with long stretches of
> fossil record of specific organisms.  Wikipedia has a very nice essay
> on the subject
>  http://en.wikipedia.org/wiki/Punctuated_equilibrium
> which carefully distinguishes between punc-eq and "saltational"
> evolution or macromutation where large jumps are made by single
> mutational events.  That is not what punc-eq really refers to and it
> is not at all antagonistic to gradual change.  It is just that a
> relatively large population of organisms is rather stable although at
> the geographic fringes of the range, gradually accumulated changes may
> result in populations rather different from the norm, new species in
> fact.  Some type of ecological event may then cause the population to
> suddenly change with the formerly isolated group  invading and taking
> over the habitat previously inhabited by the parent group.  The fossil
> record taken from a single location would show a sudden change in
> phenotype even if the changes occurred gradually.

> With the advent of evo-devo (the application of new data on
> developmental biology and gene regulation and expression to
> evolutionary biology) we now know that it is possible both for
> seemingly small mutational events to cause a rather large phenotypic
> effect and that it is also possible for the gradual accumulation of
> mutations to first produce no noticeable effect until the regulatory
> system becomes overwhelmed and suddenly reorganizes to produce a very
> large change.  In this sense, saltations and macromutations are also
> quite possible mechanisms to produce the punc-eq effect.

>> But let's suppose you are referring to a series showing gradual change
>> on a geological time-scale, i.e. a smooth transition over millions of
>> years. Would this disprove PE? Sure, in that one case. But Gould never
>> (hmmm, better make that "seldom", just in case) claimed that PE was the
>> sole means of speciation, just the predominant one. You need to assemble
>> a whole bunch of transitions and see how many of them match gradualism
>> (however you want to define that) and how many match PE.

>> A bigger problem is that it's impossible to tell if one fossil species
>> (really, a morphotype) is ancestral to another. An even bigger problem
>> is that you can't really identify species in the fossil record, only
>> morphotypes.

>>> I'm sure there is some subtle point I'm missing
>>> here because Stephen J. Gould was a rational
>>> fellow who devoted a life time of studying and
>>> investigating evolution and so is not likely to
>>> put forward an idea that seemingly runs counter
>>> to gradualism while having likely been
>>> aware of rather complete sets of fossils like
>>> that of the whale and its ancestor, horses, or
>>> from the therapsid reptiles to the mammals.
>> Gould would say that these series are not gradual transitions at the
>> level of species. Instead they're a series of species showing a
>> long-term trend. Nothing to do with PE vs. gradualism. Remember, PE is a
>> theory about speciation.

>>> Thus, if someone could shed some light on
>>> this point I would much appreciate it.
>> Sure.

> I may be misremembering but having read
> the Blind Watchmaker, in retrospect, it
> would seem like Richard Dawkins misunderstood
> Gould's position then? I don't know if you have read
> this particular book, but from what I recall, Richard
> Dawkins took great pains in showing that PE was
> encapsulated by gradualism.

>Do you know of good books or research articles
>that discuss the cumulation of mutations not
>taking effect until a "regulatory system becomes
>overwhelmed"?

>It sounds like great stuff, I'd like to read more
>on it.

>>On Jul 5, 9:44 pm, r norman <r_s_norman@_comcast.net> wrote:

><snip>

>>> On Sat, 5 Jul 2008 19:15:06 -0700 (PDT), conrad <con...@lawyer.com>
>>> With the advent of evo-devo (the application of new data on
>>> developmental biology and gene regulation and expression to
>>> evolutionary biology) we now know that it is possible both for
>>> seemingly small mutational events to cause a rather large phenotypic
>>> effect and that it is also possible for the gradual accumulation of
>>> mutations to first produce no noticeable effect until the regulatory
>>> system becomes overwhelmed and suddenly reorganizes to produce a very
>>> large change.  In this sense, saltations and macromutations are also
>>> quite possible mechanisms to produce the punc-eq effect.

>>Do you know of good books or research articles
>>that discuss the cumulation of mutations not
>>taking effect until a "regulatory system becomes
>>overwhelmed"?

>>It sounds like great stuff, I'd like to read more
>>on it.

>My comments were based mostly on my knowledge of complex systems
>theory and neurobiology where such things are commonplace.  For
>example, a series of receptors with analog or graded behavior can act
>as a digital switch (on/off only) by interacting cooperatively or with
>positive feedback.  Each component is analog, graded, or gradual but
>the ensemble acts digitally producing no effect until a threshold is
>reached and then suddenly switching to a new pattern of activity. The
>all-or-none action potential in neurons is a result of such positive
>feedback interaction.   Biochemistry has many examples of such
>cooperativity:  oxygen binding by hemoglobin is the classic example
>although the end product is not so extreme as to be all-or-none but
>rather shows a "sigmoidal" relationship instead of a linear one.  The
>basic electronic digital storage unit, the flip-flop circuit, is
>another example.

>If you want genetic types of examples, at the trivial level showing
>the effect of regulation there is the phenomenon of dominant alleles
>that produce the same effect whether one or two copies are present. So
>some flowers given either one or two copies of a functional gene that
>produces, say, red color, will always produce the same final amount of
>redness.  Other species with different regulatory systems will vary
>the intensity of the color with gene dosage so that crossing red with
>white does not produce all red offspring but rather will produce an
>intermediate pink.  That simply shows the phenomenon of gene
>regulation, not its "being overwhelmed" and "suddenly reorganizing".

>To show a rather sudden change in phenotype with a gradation of
>genetic changes, consider Huntington's Disease.  This is caused by
>mutations in the Huntingtin gene (yes, the spelling is different).
>This gene contains a repeating segment CAGCAGCAG... a so-called
>trinucleotide repeat that codes for a series of glutamine.  If the
>series contains up to 36 glutamines in a row, there is no problem.
>However 36 to 39 produces a late onset and slow progression of
>symptoms of the disease and 40 or more produces severe disease.
>There are a number of diseases caused by variation in this
>trinucleotide repeat sequence.  See
>  http://en.wikipedia.org/wiki/Trinucleotide_repeat_disorders

>As to true "genetic reorganization" on the basis of cumulative
>mutations, that was primarily a surmise on my part based, as I
>indicated earlier, on standard systems theory considerations, purely
>theoretical.  I am not familiar enough with the molecular biological
>literature to give you better examples.