Evolution in action: new plant species

[DrMatt]

Re: Blind natural selection, is the evolution's only driving force!

Suppose its is a survival advantage for a rabbit to have long legs, and loci x in the chromosome 12, is the loci for the "gene for longer legs" and its competitor for this loci, is a gene for shorter legs. It is reasonable to assume that this allele competition will end up with the gene for short legs as extinct.

No.
Longer legs may make mating more difficult. The long-legged rabbits may flourish where foxes tend to give chase and eliminate the short-legged rabbits; in neighboring regions where the foxes are loathe to go (e.g. because of briar patches), short legs may prevail because of their greater proliferation. This split may be the first in several which eventually lead to two populations of rabbit which are somehow different enough that they are no longer able to mate--or to produce fertile offspring. Or, this may not happen.

 

[Guest]

Originally posted by Peter Soderqvist
Suppose its is a survival advantage for a rabbit to have long legs, and loci x in the chromosome 12, is the loci for the "gene for longer legs" and its competitor for this loci, is a gene for shorter legs. It is reasonable to assume that this allele competition will end up with the gene for short legs as extinct.

Originally posted by Dr.Matt

No.
Longer legs may make mating more difficult. The long-legged rabbits may flourish where foxes tend to give chase and eliminate the short-legged rabbits; in neighboring regions where the foxes are loathe to go (e.g. because of briar patches), short legs may prevail because of their greater proliferation. This split may be the first in several which eventually lead to two populations of rabbit which are somehow different enough that they are no longer able to mate--or to produce fertile offspring. Or, this may not happen.[/b]

To expand on this a bit...

There are three basic types of selection: stabilizing, directional and disruptive. I'll avoid the differential equations that define them rigorously and define them as follows:

o stabilizing - tending to maintain the status quo of the genome's allele frequencies

o directional - favoring one allele over others and shifting the genome's allele frequencies over time

o disruptive - forcing a divide in the population such that two different alleles become favored over all others.

Peter is describing directional selection, and Dr. Matt is describing disruptive selection. As a somewhat technical aside, in the directional selection case, selection doesn't eliminate alleles. Selection can only reduce alleles as far as the mutation-selection equilibrium value, which is always non-zero. A random force, genetic drift, is responsible for eliminating alleles. Even then, mutation can always reintroduce it from time to time.

Cheers,

 

[Soapy Sam]

Peter- Long time since I read Schrodinger's little book. Extremely perceptive considering it predates Crick & Watson. My own evolutionary position is firmly Dawkinsian if there is such a word. I'm quite content with the idea that evolution is a matter of relative gene selection. There are numerous processes by which gene selection can take place, ranging from genetic drift, mutation, sexual selection etc. all the way to dropping an asteroid on a planet and awaiting events.

But there is evolution and there is Human description of evolution. One is a process that happens by itself, the other is a question of education, perception and classification. At times, it will be simple and useful for us to describe evolution in terms of allelle competition; at other times, the species will be a useful concept; sometimes even ideas of group selection may be useful.
These are questions of explanatory model and metaphor- a description of reality, not to be confused with reality itself.

Where "species" is a fruitful concept, it should be used. Where it limits our thinking, we should find a tool which works better. The fact that many people of intelligence have struggled with the speciation argument for two centuries suggests to me that it is often not a helpful concept. - Hammegk's (probably deliberately) naive question about turning fruit flies into wasps is a classic example. To any intelligent alien from Andromeda, it would be instantly apparent that fruit flies and wasps are closely related lifeforms. Any such alien would immediately be able to identify both as Earth Arthropods. It would point to the similarity of hox genes, the near identical structural form and material: Indeed it would perhaps be pushed to tell them apart. Species difference would be just too trivial to mention. To Hammegk, they are different species, as if that somehow makes them fundamentally distinct. The effect of the terminology is to enforce a distinction where no distinction of relevance (to evolutionary theory) exists.
(Of course it matters to the wasp!).

This is a historical effect. Biology began with classification. Linnaeus stressed the importance of species and his system was grabbed with glee by the many studious collectors of his day. When he tried to establish a similar mineral classification, it was universally rejected as impractical.

My point about overuse of the specific distinction is very simple. If your classification system is causing people to miss the point, then it should be altered.

 

[pupdog]

This (the original thread) is not the first example of claimed witness to speciation.

Just in the past month or so (Science 299(5607):654-655) had an article describing sympatric (in the same area) speciation among fish in Lake Baikal and Lake Victoria--seems it might have been related to color vision & the human influence of making the waters murky.

It seems that Creationists commonly think that "evolution" means near-instantaneous, bizarre changes--"a bat with one wing," a dog "evolve" into an elephant," or "fruit fly to wasp."

When we think of species as being reproductively isolated, it may not be obvious (dog & cat)--some fruit flies & other bugs can only be identified by careful examination of their genitalia. Some critters may be isolated in ecological terms, even if some biologist can collect & mix gametes & produce viable offspring. Genetic analysis can give some idea of the extent of isolation, as well as the timing thereof.

 

[hammegk]

Puh-leeze. Enough with the drive-by assertions, man. Post after post devoid of content, yet each one putting in a little jab, followed by one long duck.

Cheers,

It is unfortunate people as all-knowing and intelligent as you sometimes encounters a dumb know-nothing like myself.

However, from time to time you appear to conclude that one of my drive-bys contains sufficient "content -- or lack thereof" you need comment on it.

My mission here is admittedly different from yours; I have no interest in converts to my way of thinking. My interest stops once I've clarified to my satisfaction some particular point.

When I began using the JREF board, I would have considered my self a dualist. Posters here have convinced me that dualism is not logical, and in fact is a less tenable position than materialism -- even under the materialism definition of some that is so inclusive that nothing else could be left. Hmm, so "energy" is something we "measure" but actually no we don't know what it is, and as materialists realize it is not scientific to even speculate.

I mentioned I'm onboard evolution from an Idealist perspective, which can and does provide some logic for what the record is interpreted to depict. I.E. LIFE strives towards organisms that support higher & higher consciousness (human the best we know of at the moment). No problem with the first male/female pair for each new critter which has apparently happened here a very large number of times -- other than time, randomness, and luck. And yes dropsila may well evolve -- but, a fly is a fly is a fly.

I suggest that the mismatch between gravity, the other 3 forces, and a fifth? (currently nominated for Higgs) is a much larger cloud on the horizon than was radioactivity 100 years ago. Are we beginning to look at energies that destroy solar systems (or more) rather than life on a single planet? For us my main thought for the next "oops" will come from genetic engineering; damn, who thought we could come up with a virus that kills a human in minutes, lives forever in all conditions, and infects yet is benign in every other lifeform on the planet.

Cheers back at 'ya.....

 

[DrMatt]

Perhaps another time. I am on-board with evolution from an idealist's point of view.

I am curious, have we seen any wasps yet?

I haven't seen any examples of diamonds showing up embedded in loosely crusted sandstone. Does that arbitrarily made-up failure disprove all of geology?

We've observed zillions of objects the size of the sun or bigger, all in space, but the earth hasn't collided with any of them. Does that arbitarily made-up failure disprove everything we know about gravitation?

We've observed zillions of acorns over time, and not one has ever become a blowfish, so does that arbitarily made-up failure disprove the theory that acorns sometimes change into bigger life forms?

Hey, I'm just a musician, but even I can see that this "any wasps" bit is really stupid.

 

[Soapy Sam]

I've seen grass turn into cows.
I once saw a man turn into a street.

 

[hammegk]

Hey, I'm just a musician, but even I can see that this "any wasps" bit is really stupid.

Stupid? Perhaps. We probably agree that *every* "species" of fly remains a fly, so far at least.

Any materialist/atheist evolutionist would be quite pleased to have an unspeculative example of fly-to-wasp to trot out. Even arthropod to arthropod just doesn't provide a real open & shut case. Soapy's aliens should have trouble seeing what the fuss was all about, yet this would be trumpeted as absolute proof of "evolutionary theory".

Evolutionists make do with 6" horses to 6' horses, a speculative land critter to whale (oops went the wrong way), a "feathered dynosaur", and a great number of other speculative "links" to make the case for time & randomness without intent. "Evolving species" of bacteria also get mentioned often.

Again, looked at with life/consciousness/will/what-have-you as the basis of what-is, it becomes easier to see some potentially rational basis for terran evolution, and expect "evolving life" to be widespread (in some universal Bergsonian sense ).

 

[rwald]

Wait! Wait! I get it! You're saying that species of the fly "kind" can evolve into other species of the fly "kind," but not into other "kinds," such as the wasp "kind"! OK, now we're getting somewhere.

Oh, by the way, could you be so kind as to describe a cohesive, biologically-sound definition of "kind"? Thanks.

 

[hammegk]

Oh, by the way, could you be so kind as to describe a cohesive, biologically-sound definition of "kind"? Thanks.

That seems even more problematical than "species -- oh, can't breed you say".

Let's stay simple. What do DNA based classification schemes imply to you at "species" level? What is the DNA code difference between dropsila & the common house fly? What DNA level mechanism stops the potential for cross-breeding?

After we explain flies, we can move on to wasps vs. flies.

Or would you rather move directly to the prion/virus level? Or maybe bacteria?

 

[FutileJester]

In fact, a fly producing a wasp would be evidence against evolution as we understand it. Evolutionary theory predicts that changes of that magnitude happen over huge periods of time, far longer than anyone's been capable of observing these things in laboratories.

 

[rwald]

For the record, the gloves are coming off...now.

Here it is, the official definition of species, the "Biological Species Concept," as proposed by Ernst Mayr: Species are defined as "groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups." That's it. There's no magic to the definition of a species. Any species could theoretically evolve into any other species, given enough time.

Of course, you need to remember that all presently existant species are equally old. We can theorize that "primitive organisms looked very much like modern-day bacteria," but all species that we see to day are equally evolved. Asking whether one modern-day species can evolve into another modern-day species is like asking whether you can ever "evolve" into your sister. No, you can't, but your sister and you have a common ancestor. Likewise, the fly and the wasp have a common ancestor, a long-extinct species which eventually evolved into both the fly and the wasp.

Evolution works on large timescales. Even punctuated equilibrium, which suggests that changes happen much faster than Darwin suspected, works on timescales of "only" tens of thousands of years. Yes, any species which evolves today will look like species closely related to it. If a fly suddenly gave birth to a wasp, it would disprove all extant versions of evolutionary theory.

Besides, evolution works to find the organisms best adapted to their environment. It doesn't specifically try to produce any one organism; it just tries to make organisms which are most "fit" in their environment (and "fit" is not a tautological term; it relates to what elements in the environment most limit the expansion of a species; those individuals which best circumvent this limiting factor are the "fittest"). If evolution were to start again, it would be unlikely that the same variety of animals would evolve. The experiment which would most reflect the true nature of evolution would be to put a group of flies in an environment which stresses them in a particular manner, and see if they respond to that stress by evolving into a new species. You could then take that new species, and put it into another environment which would stress it further, and watch it evolve into yet another new species. After many repetitions of this, you would create something which was not a fly. Of course, this would take thousands of years...but if that's what creationist "scientists" demand as proof, they should get started right away. I guess it's better than Kent Hovind, who requires that scientists create the Big Bang in a laboratory to prove evolution.

 

[Hazelip]

Besides, evolution works to find the organisms best adapted to their environment. It doesn't specifically try to produce any one organism; it just tries to make organisms which are most "fit" in their environment

I'm sorry, but this is just a bit too close to the pathetic fallacy to keep me comfortable. I'm with you, and even agreeing with you nearly 100% of the time on this subject, but I don't think the mechanism of evolution is a directed mechanism at all.

Isn't evolution simply the process by which the creature most fit survives, produces viable offspring, thusly reproducing the new features that permitted the original off-shoot to survive where its ancestors perished? It's not a process that seeks a solution to a problem, it is a process that simply occurs. Only our interpretation can lend it any meaning, that is to realize that evolution benefits the superior (to the circumstance or environment) life form...

 

[hammegk]

.....the fly and the wasp have a common ancestor, a long-extinct species which eventually evolved into both the fly and the wasp. ...

So currently theorized; at least that is true.

.....If a fly suddenly gave birth to a wasp, it would disprove all extant versions of evolutionary theory.

[aside] Damn nukular reactors, hrmmph. [/aside]

....The experiment which would most reflect the true nature of evolution would be to put a group of flies in an environment which stresses them in a particular manner, and see if they respond to that stress by evolving into a new species. You could then take that new species, and put it into another environment which would stress it further, and watch it evolve into yet another new species. After many repetitions of this, you would create something which was not a fly. Of course, this would take thousands of years...

As a theory, sure sounds plausible I agree. I mention dropsila because as I said a kazillion generations have been "stressed", DNA re-arrangement done, etcetc. Yet, a fruit fly remains a fruit fly.

The time aspect is noted, but it's like looking for a decaying proton; expect one every 10^32 years, OR watch a lot of protons. Either way, no more luck with fly to "something else", decaying proton, and no derned monopole magnets either!

 

[rwald]

Isn't that what I said? I realize I was anthropomorphizing to some extent, but that's basically what I meant. If evolution seeks to solve a "problem," per se, it's some environmental stress which is limiting the reproduction of the individuals. The individual whose genetic advantages allow it to partially circumvent this stress will produce more offspring, and its genes will be over-representated in the filial generation. Maybe I could have made that clearer, but I think we both understand one another.

 

[rwald]

It's not a matter that biologists can "speed up the process" with a lot of fruit flies. I'm reminded of the old adage, "You can't get a baby in one month by screwing nine women." Unless scientists somehow managed to drastically decrease the generation time of flies, they're working no faster than natural evolution. They might be able to apply pressures in a more specific fashion, and thereby cut the timeframe down by a factor of 2 or 3, but even if they did that you would complain that it was "artificial selection," not natural selection. You simply can't speed up evolution.

And a fly giving birth to a wasp would still throw a monkey wrench into evolutionary theories, even with mutations. Evolution is about how natural selection selects the best mutations and uses them to make new species. Random mutations alone can occationally make new species, but it wouldn't make any large jump (such as from fly to wasp).

 

[Hazelip]

I just wanted to be sure. Tone is not something that can be easily inferred on a message board.

Besides, until I started actually reading Interesting Ian's posts, I thought he was an intelligent person. I just sought clarification. Thank you for providing such.

Isn't that what I said? I realize I was anthropomorphizing to some extent, but that's basically what I meant. If evolution seeks to solve a "problem," per se, it's some environmental stress which is limiting the reproduction of the individuals. The individual whose genetic advantages allow it to partially circumvent this stress will produce more offspring, and its genes will be over-representated in the filial generation. Maybe I could have made that clearer, but I think we both understand one another.

 

[Guest]

I'm sorry, but this is just a bit too close to the pathetic fallacy to keep me comfortable. I'm with you, and even agreeing with you nearly 100% of the time on this subject, but I don't think the mechanism of evolution is a directed mechanism at all.

Isn't evolution simply the process by which the creature most fit survives, produces viable offspring, thusly reproducing the new features that permitted the original off-shoot to survive where its ancestors perished? It's not a process that seeks a solution to a problem, it is a process that simply occurs. Only our interpretation can lend it any meaning, that is to realize that evolution benefits the superior (to the circumstance or environment) life form...

Hazelip,

On the population level, rwald is right, the population is "solving a problem." The problem is producing more of itself. You are also right to point out that it isn't teleological, and, in that sense, "directed."

You may want to see my earlier description of the three basic forms of selection to see where "directed" clearly comes into play.

Cheers,

 

[rwald]

.

 

[hammegk]

You simply can't speed up evolution.

Not Darwinism as currently stressed. Too many theories & mechanisms -- none demonstrated other than by speculation.

And a fly giving birth to a wasp would still throw a monkey wrench into evolutionary theories, even with mutations. Evolution is about how natural selection selects the best mutations and uses them to make new species. Random mutations alone can occationally make new species, but it wouldn't make any large jump (such as from fly to wasp).

Neither of us know the correctness of the fly to wasp jump, but I contend any evolutionist would leap on such an event as "the final proof". (Given of course there was a simultaneous appearance of a male/female pair. )