This is something that frequently comes up in the CvE debates -- that evolution necessarily increases diversity (creationist) versus diversity is a result of evolution and can fluctuate (evolutionist).
The first problem is how to define (biological) "diversity" ...
Fairly obviously we would use the second definition.
If we take it to it's extreme it would mean each individual organism differs from all others, so the sum total of all organisms would be the total diversity at any one time. The problem here is that there is ongoing death and ongoing birth, and the total numbers do not change significantly except in times of major extinctions.
If we limit it to species (per example in the definition), then diversity would be measured by the sum total of all species at any one time. Again, the problem is that species are born and die, and the total numbers do not change significantly except in times of major extinctions.
Either way the concept can be quantified (although actual measurement could be extremely difficult), so the increase or decrease over time could be measured and compared.
That an individual organism or a species can die at any time shows that diversity does not always increase due to evolution (mutation and natural selection processes).
Evolution is the change in hereditary traits in populations from generation to generation, and this results in added diversity, when new species are "born," or in loss of diversity, when old species "die." The diversity we see is the result of evolution, but it is not a necessary result, just what happens.
What this data can tell us is whether more or less species are being developed vs going extinct. This in term may inform debates on whether global warming or the impact on man on the environment is having an effect on biological life and the diversity of life as we know it.
But I don't see it as being a critical factor in the study of biology or evolution.
I guess the questions are: am I missing something? Do creationists see this differently? Is there some tie-in to "macro"evolution?
This came up in debate with MurkyWaters regarding the definition of the theory of evolution, and it seemed a puzzle to me why he was so intent on it (other than to try and make the definition as impossible as possible).
I guess the questions are: am I missing something? Do creationists see this differently? Is there some tie-in to "macro"evolution?
The line at the top is suppposed by Darwin to transform, back, into the boundaries of any given country, and generations later, there are six places variation supposedly wrought. Darwin's notion of diversification in form-making is tied to diversity triangulatable in space. It did not seem to me to be any old kind of novelty creation.
If a creationist wishes to argue not against Darwin's view but rather something created 100yrs or so later, they could simply point out the no one has followed up on Wright's notion of a gamodeme strictly. People are arguing whether or not Wright's complex process exists in nature but the question could be could man create isolatable breeding communties able to outevolve (into currently unoccupied regions of niche space) currently endemic genetic variations in nature, given nature.
I suspect however that a creationist position against macroevolution would looke pricipally to showing that Darwin's spatial restriction of diverification can not exist on our actual Earth and thus his process for giving rise to 5 lineages from two within a country necessarily collide. I have not made this determination. It might be possible however. Gould however takes the position that Darwin failed miserably to explain diversity hitching his bit to levels of selection rather than levels of organization.
I think Panbiogeographic statements can be read in part to provide the spatiality that is not simply a mirror image (among E, F G) as Darwin seems to have figured it. Temporally it matters how much time is supposed to be represented from the top to the bottom. The Earth is near spherical after all.
Someone reading Darwin's "Origin" one can encompass his notion of diversity via the angles here (only diagram in the book):
Yes, and in that diagram you can see that diversity can increase but that it doesn't have to: there are several extinctions shown and places where a horizontal line would have more species than at the end.
I think we can agree that the observation that there are more species now than at the (presumed microbial) start would be an increase in diversity that is explained by this process, but not that an increase in diversity need occur at any generation time.
I suspect however that a creationist position against macroevolution would looke pricipally to showing that Darwin's spatial restriction of diverification can not exist on our actual Earth ...
... Temporally it matters how much time is supposed to be represented from the top to the bottom. The Earth is near spherical after all.
Yes it would come down to a matter of the limitations of time and space. One thing to point out is that the number of species known to exist and have existed could of it's own mean that a minimum time is needed no matter how you cut the timelines.
This would be a matter of possible biodiversity and ecological support.
Re: Darwin's increase in diversity compared to Wright's
Yes Darwin did not make it clear how many generations are represented with each line.
He was however trying to apply Malthus and to do so requires some macrospatial boundary IN which to compare the geometric growth of reproductions to the arithemetic increase of the food. To be willing to reduce the places in an actual geography on Earth envisaged with this math to the petri dish while logically scaling ok, I find leads to suspcious use of the notion of "metric".
The diversity where, despite some extinction, becomes represented on both halves of the figure is to present how there need be NO LAW to the extinction of forms.There has to be an origin to the "species" with it. To say that the Mendel binomial not available to Darwin expunges his planar accompaniment to the words in the text seems like a cop out to me. It seems to me that by restricting one to a sphere rather than an infinite plane Darwin's diversification DOES become constrained in some visiable way. I would love to have some other way, other than words, to express this.
Now if one of course does reduce the scale, without any intention of disrupting the topology (definition of 'neighborhood')implicit AND one assumes that it may not be on the Earth that a "country" is supposed to present linearly as per the diagram, then in bringing it back to macro size after the process has commenced, one is not subject to my restrictive configuing because one has the Universe as the outside bound of any niche rather than the rotating and revolving place we can in our best of moods can still be phoned home.
If I reject Malthus, it is a piece of cake, to keep with your obervation, but it was in relying on that, that I think Darwin failed, not as Gould supposes, of failing to start with species selection but failing to realize that a number of things to be selected is not so easy to even describe let alone cut out of nature for human comprehension.
Correct me if I am wrong, but it seems to me that Wright's isolation by distance is simply the ability to genetically support any given branch"" of Darwins' whether extinct or extant in the picture.
Wright still maintained that some immigration from the population (as a whole) could still enter a given braching (Darwin compass of a country) This is why Wright spoke of that, THEN the stepping stone model (some where in between the middle of the diagram) then density dependence and now that then, a continuum(see quote below). If one is not a reductionist it is hard to simply accept the scaling operation creates not but a torque force of minsucle magnitude.
This continuum must be one to one and onto Darwin's linearity it seems to me. I have not tried it but it seems to me that the purely arithemetic and geometric properties of transfinite numbers may supply a different drawing board from which to circumspectly represent Darwin's reasoning but with a different, not restricted to the plane, resultant depiction. But then what a "number" means biologically would be composite of genotype and phenotype, and that being hard for one without the intuition to so proceed, is unlikely to motivate in readers. So it would be easier for me to stick to tyring to interpret the already suggested evolutionary ideas.
quote:The simplest pattern of subdivision to deal with mathematically is the "island model." In this, in pure form, the population is divided into groups that are panmictic within themselves, except for reception of smal proportions of immigrants, representative of the population as a whole.
In most actual cases, immigrants come largely from beighboring groups and there is more or less "isolation by distance." Such patterns may be calssified by the degree of continuity of the population. The island model pases into the "stepping stone" model, this into the model of a continuum whith scattered clusters of high density, and this into the model of a uniform continuum.
page 290 in The Theory of Gene Frequencies by S Wright
quote:you want to debate. Is there a question in there somewhere?
RAZD came out after I posted with,
quote: in that diagram you can see that diversity can increase but that it doesn't have to: there are several extinctions shown and places where a horizontal line would have more species than at the end.
I am suggesting that maybe IT DOES have to according to Darwin, but not necessarily by post neo-Darwinian assertions. Look:
The question as RAZD has it put, is-is, are a-z "at the end" necessarily containin more species than on Darwin's A..L line of beginner's luck. In between I have labeled two lines "greater number" and "lesser number" to accord with Darwin's use of the word "number". The question is, are there actual places where a lineage would have more species than at the end. Where is the end?
This would depend on where Darwin's Fline necessarily is represented in my figure. This I have not determined. It may be that a measure of adaptedness is needed as Dobshansky wrote in the 60s (quote available). Regardless GS Carter in 1957 wrote
quote:In all these ways Darwin's theories semed to strike at the foundations of religion and metaphysics. Much of the conflict was inherent in the intellectual position of the nineteenth century. Sooner or later fundamentalist views were bound to come into conflict with the results of science, and the materialism of the scientists was already disputed but the metaphysicians. Darwin's book gave the shock that brought the conflict to the surface, but, i that shock had not been given, the causes of the conflict would still have been there and dispute would have taken place at some other time
a hundred years of evolution page 67
I feel that this outline of Darwin's depiction drawn via light cones in quaternionic space supplies the very "surface" mentioned by Carter.
Dobshansy subsequently wrote,
quote:Adaptedness is in principle, measureable; in practice, the measurement is extremely difficult. Satisfactory methods of measuring the adaptedness especially in the adaptedness of populations, are yet to be devised. Awkward questions are sometimes asked, even by some biologists: In what sense can mankind be said to be better adapted than a fly or an alga or a bacterium? Are the so-called higher organisms in general any better adapted than the lower ones? If not, then was not the whole biological evolution a wasted effort? These questions are not easily answered in precise terms, and our inability to give such answers attests tothe unsatisfactory state of our understanding of the phenomena of adaptedness and of their roles in evolution.
Adaptedness and Fitness in Population Biology and Evolution 1967 p113
Gould has decided that the position on adaptations had hardened in this time frame. Instead of finding this surface I revised, he expects us to wear the cap of his team that finds instead the arguments within evolutionary discussions ARE those of Paley-Agassiz 'transmorgified' (read Darwin and Darwin's "god" here). If the surface I am presenting is a better rendition than Goulds' then perhaps there was NO hardening but rather a softening up and faliure to pursue questions to an end.
It seems to me that Stanley in the 70s who has said (quote in Lloyd's book) that "species selection" was never about general adaptedness may be correct historically but wrong rationally. It might be instead that the "hardening" was a failure to develop the methods called for by Dobshansky. Could it not be that the Gladyshev law contains such a law for the extinction of forms?
Now if your question turned into mine is not comphrended, all I can do is rephrase it. The culprit is probaby what the word population means and what a "check" is on one. That seems to underlie Hoot persistant use of sexual selection but that is not my conversation...
The places in dispute or under possible extinction directions seem to have been denoted by Carter with ,
quote:These local populations of a species vary enormously in size, from the small number of individuals that may inhabit a pool of water to the many millions of a shoal of herring in the sea or of a planktonic species in a lake. All intermediates between these extremes of size occur, Further, this type of distribution is as general in the common species as in the rarer; the common species is distinguished rather by the shorter distances that separate its local populations than by any lack of distinctness between the populations .
The local populations of a species are isolated from each other more or less completely by the unsuitable environments that separate their localites. Here again there is very great variability. The isolation is probably almost complete between populations on islands separated by considerable streches of water, or in isolated bodies of water on land. In many other cases it may be much less complete, but recent study of ecology has shown that the movements of many animals are much less than might be expected, Populations of field mice separated by a few hundred yards have been found not to mix; snails do not travel more than a few yards in a year; and even the birds of a wood have been found not to mix with those of another wood a mile or so away. In all these cases there is a very definite isolation between populations which are by no means distant from each other.
These local and at least partially isolated populations may be called demes.
It is in these demes that micro-evolution goes on. As soon as two populations are isolated, they will begin to diverge, either in adaptation to small differences in their environments, or because mutations that occur in one do not occur in the other.
Carter op.cit page 149
For physicist's (using time as the scalar component (biology may? not use this))use of light cone representations with quaternions see doing physics with quaternions
Evolution happened, but how? How would â€śsurvival of the fittestâ€ť explain the origin of the fittest? The notion that â€śnatural selectionâ€ť might somehow organize a bunch of genetic accidents into intelligently interacting biological systems (RM&NS) doesnâ€™t sound very convincing to me. But then lots of scientific theories donâ€™t sound very credible to me. For instance the one about multiple universes -- the notion that an infinite number of universes exist, but our is the only one that â€śjust happensâ€ť to be intelligently organized. However, no one attacks me if I make fun of the multiple universe theory. No one has gone to court and ruled that skepticism of multiple universes canâ€™t be expressed in the classroom.
If biological systems are intelligently organized, rather than the result of random mutations accidentally self-assembling for no particular reason, life can be described as â€śintelligently designedâ€ť. Just because some religious people are also skeptical of RM&NS, and believe the intelligence responsible for the organization of living systems is their god shouldnâ€™t negate the reality of the intelligent organization of living systems. As a religious agnostic, I regard that intelligence as a natural responsiveness of living systems. Used organs develop and unused ones atrophy. Bodies explore ways to heal wounds, fight infection, and respond to heat, changes in altitude and novel food sources. If religious people want to claim their god participates in those process, I have no objection. The only thing I object to is suppression of academic freedom. I object to the harassment, denial of tenure and loss of jobs for anyone who wants to explore the role of intelligence in the organization of living systems. I resent the fact that such discussions are not permitted in scientific journals.
By the change in hereditary traits in populations from generation to generation. See Definition of Evolution to discuss further, as this is off-topic here.
How would â€śsurvival of the fittestâ€ť explain the origin of the fittest?
It doesn't need to. The ecology is constantly changing in many little to major ways, and "fittest" just means best able to take advantage of the ecology available. Any organism has some "fitness" to any ecology, and some will be better than others. Perhaps you can start a new thread to discuss this further, as it is off-topic here.
do creationists believe evolution necessarily increases diversity?
It's more that they believe (or have been told by creationists) that the theory of evolution says that there must always be an increase in diversity, which (of course) is wrong.
RADZ, you may be right about the "theory" of evolution, but the practicality of it seems to be contradicted by John Sepkoski's "death graph" of marine families, redrawn below from S. J. Gould's The Book of Life (2001, p. 107):
At a macroscopic level Sepkoski's graph shows six global mass extinctions of marine life in terms of families. Since the Permian extinction there appears to have been a 'punctuated" increase of diversity at a rate of about 3 families per Myr.
Why isn't this evidence of a naural increase in biodiversity?