Evolution and Increased Diversity

I already said in Message 14: My point is relevant to the OP definition of diversity: So what's the problem?And could you put some meaning behind these words? Correlation with what? This is not a statistical graph. And who said anything about causation? Growth of biodiversity was unabated by the worst of mass extinctions. No, the TOE does not predict this. But some refinement of the TOE ought to.”HM

Even ignoring the mass extinction events like the Permian we see a constant flux up and down in the number of species, and this alone shows that increased diversity is not a mandatory result of evolution, that if anything it is a "two steps forward, one step back" kind of process.It is a likely event over the long term because of the way random events work, and the fact that natural selection plays a role in surviving random environmental challenges so that the next occurrence is less threatening to those species that survive one.Evolution explains the diversity we see, but this is just the record of life on earth, an ad hoc result. It just happens to show increased diversity over most periods, just as it does show massive loss of diversity during some periods. The balance between diversity growth and diversity loss is not due to evolution, per se, but to the record of environmental change, sometimes ferocious sometimes benign.A more or less hospitable planet would have different results, and all evolution can do is adapt life to the planet such that over time the planet (if things remain the same ... ) would be more hospitable for the kind of life that exists than before.Enjoy.

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I'll be very interested in seeing any other ad hoc results of biological evolution. Do you know of any? Don't know what you are saying here. If we look at marine families there an unmistakable trend toward evolvolving diversity, unless you know of another way diversity happens. How do you know? What is there about the TOE that supports your assertion that a macroscopic trend toward greater diversity would not happen on another habitable planet?I agree with you that evolution does not necessarily lead to diversity on a shorter timescale. A lot depends on how we measure diversity. But if we measure it using fossil records of marine familiies there is no doubt that diversity growth has been irrepressible on the largest timescale here on Earth. From Sepkoski's graph one might conclude that, on a broad timescale, mass extinctions were boons to biodiversity.”HM

Any species you care to name is an ad hoc result -- it is what happened, it is not what needed to happen.Wings on birds, bats, butterflies and bees are ad hoc results.Natural selection of beaks in Galapagos finches is NOT an ad hoc result, because it directly involves selection for the result, but whether the finches end up with large or small beaks after multiple generations of selection back and forth is an ad hoc result of whatever the final environmental factor was. capice? But you can't become less diversified than extinct. Start with a single species, and toss a coin: heads you have a new species, tails the one you had goes extinct. Keep running this experiment and you will have a number of cases where everything dies out. You will also end up with some that have a lot of species. The factor under consideration was the level of hospitality of of that other planet: if it had a lot of extinction events due to meteors and the like it could wipe out life.EnjoyEdited by RAZD, : finished

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RAZD, you said in Message 17: I asked if you knew of any other ad hoc results, meaning ad hoc results for planets other than Earth. You seem to be quite ready to assume, without any evidence whatsoever, that ET life exists, but you also assume that it wouldn't diversify in a way similar to Earth's life. I don't see how you can justify these combined assumptions. For the only kind of life we know of”Earth life”Sepkoski's graph makes it clear that historical diversity, measured in marine families, ultimately recovered from mass extinctions to exceed prior diversity levels.And your ad hoc argument is not too strong. Aren't all environmental changes ad hoc with respect to how biological evolution works?I my mind, to validate your argument you would need to show that the diversification of marine life was not associated with biological evolution. No so easy to do.”HM

but that is not at all what I said.

It's the "ad hoc" part I don't get. The Oxford Dictionary defines "ad hoc" as: "formed, arranged, or done for a particular purpose only". I don't think you mean to say that butterfly wings were formed for "a particular purpose." Do you?Again, from your OP: Well, yes, I do think you are missing something, and I don't care what the creationists think they see. My point is that we have empirical evidence of life diversifying on a macroscopic scale, and doing so irrepressibly, even after mass extinctions. Why shouldn't we expect the TOE to account for this? You're right; it doesn't. But given what Sepkoski has shown (see Message 14), why shouldn't there be "a law of macro-diversity"?”HM

Preamble:
Life, through the evolutionary process "explores" all accessable niches in the biosphere. Thus the degree of diversity is shaped by what the environment allows, what is reachable and what is selected for.Here is my statement of the law:
Biodiversity increases to the maximum that the current environment allows and that the evolutionary processes working with the results of historic contingencies make possible.Thus if an environment is very restrictive (e.g., Mars today) the resulting maximum biodiversity will be very low.Since all living things themselves are part of the environment we ave a corollary:
After a contingent mass extinction the rate of increase in biodiversity will be high.

This would seem to be oriented toward "carrying capacity" for biodiversity, which I can agree to. Maybe all we need in a "law of macro diversity" is already accounted for by ecological theory. Yes, if niche/hab controls macro diversity. But (speculatively) if genes can be attributed to modifying habitats for increasing biodiversity, then maybe I can assume that macro diversity is at least partly driven my genetic variation. No?”HM

The problem is that the Theory of Evolution does not necessitate an increase in biodiversity.Biodiversity has increase, as exemplified by your graph.This increase was not strictly due to the process inherent in the ToE, it was also a result of changes in the environment.Sometimes creationists say that evolution must increase diversity. Basically all I'm saying is that it is not true that it must.You chart was use as a correlation of the increase in biodiversity to the process of evolution. Evolution has happened and diversity has increased. That is the correlation. But, that does not necessarily imply causation. That evolution must cause an increase.Evolution can lead to a decrease in biodiversity.Do you disagree with that statement?

But isn't evolution itself associated with changes in the environment? And wouldn't you agree that diversity is a consequence of evolution? Yes, of course it can. But how then would you account for the macroscopic increase in biodiversity, per Sepkoski's graph? If you say it may be a peculiar to Earth but not necessarily the case elsewhere, then I say show me some of that "elsewhere" data.”HM

I don't know what you mean when you say "genes can be attributed to modifying habitats ...". Yes, I think so. That is what others mean by "ad-hoc" I think. It is contingent on the environmental conditions. Obviously some environments will allow for a wider diversity to develop and others will not. I don't see that it is any big deal at all.BTW, I think those using 'ad-hoc' should be using the word contingent. I must not understand this. It is so obvious that it seems odd to say it. Diversity obviously stems from genetic variation. Mutation (and other) generates diversity at the genetic level. Whether such diversity makes it into surviving phenotypes is dependent on the environment.

Corollary:
The spread of biodiversity into new ecologies is limited by the existing biodiversity's ability to reach those new ecologies.Life couldn't diversify on land until it could live on land. We won't be able to diversify on Mars until we reach Mars. For replacing organisms extinct due to catastrophic but relatively rare events. If the catastrophic events are relatively common it will be difficult to move in to fill the ecologies between the extinction events.Enjoy.Edited by RAZD, : ingles

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Especially when you have competition for dwindling resources, or when one species overruns an ecology making it difficult for other species to survive in the same area. Like say, caused by human overpopulation ...Enjoy.

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Some other definitions that may help:Ad hoc Definition & Meaning | Dictionary.com

quote:

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adj.
1. Formed for or concerned with one specific purpose: an ad hoc compensation committee.
2. Improvised and often impromptu: "On an ad hoc basis, Congress has . . . placed . . . ceilings on military aid to specific countries" (New York Times).

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adjective
1. often improvised or impromptu; "an ad hoc committee meeting"
2. for or concerned with one specific purpose; "a coordinated policy instead of ad hoc decisions"

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A phrase describing something created especially for a particular occasion: “We need an ad hoc committee to handle this new problem immediately.” From Latin, meaning “toward this (matter).”

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Contrived purely for the purpose in hand rather than planned carefully in advance. E.g. "We didn't know what to do about the sausage rolls, so we set up an ad-hoc committee".

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To me ad hoc means arbitrarily developed to deal with something after it has occurred.Basically in this case I mean it is an arbitrary, improvised or impromptu result, and not a necessary result. This is similar to the post hoc ergo propter hoc logical fallacy. But this is only what has happened (so far) on earth, it isn't necessary that this happened. It has not happened on Mars.Enjoy.

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