Questions on speciation

[ReUsAbLePhEoNiX]

Most excellent visual showing observed speciation of a songbird..note the variation in songs at the bottom of the pic

 

[chilehed]

My work is with automotive engines, not nearly as complex a system as biology (by what, a few dozen orders of magnitude? if I was REALLY smart I could’ve majored in something else...) but enough to give me an education in how a (supposedly) simple change to one subsystem component in a complex system frequently requires changes to seemingly unreleated subsystems in order to keep the whole think from crashing. So I have to remark on your assertion that each mutation will aid survival in comparison to the individuals without it. It seems more likely that each mutation will rather hinder the survival of the individual unless the whole new system is present (which is what I was assuming), in which case the 1:1,000,000 odds are correct, and, about the time there are 9 mutations floating around the gene pool, 1/3 of the individuals will get be defective out of the box.



I also have a hard time swallowing that Great Danes and Chihuahuas are different species, and reconciling your reasoning with your implication that I’m not already a different specie than those people on another continent. Isn’t assortative mating properly considered a mechanism that results in the isolation of gene pools, rather than a sign that there is a a new specie?



Have any assortative mating experiments with insects included artificial insemination to test for genetic incompatibility after 500 (or 1,000 or whatever) generations? Perhaps that was buried in the links above and I missed it? It would go a long way to closing the loop (would also take some teensy-tinesy stirrups...).



I’ll mull this over some more, thanks. I wish I had the time to take a class...perhaps you could suggest some decent texts on the subject, suitable for an engineer but not too advanced?

 

[Jet Black]

My work is with automotive engines, not nearly as complex a system as biology (by what, a few dozen orders of magnitude? if I was REALLY smart I could’ve majored in something else...) but enough to give me an education in how a (supposedly) simple change to one subsystem component in a complex system frequently requires changes to seemingly unreleated subsystems in order to keep the whole think from crashing.

biologically this is not really the case. you sound like you are discussing irreducible complexity here, and this argument invariably falls apart under analysis, since

1) while something is irreducibly complex in that by taking a single part away, the whole thing breaks down, the system can still evolve to that level of complexity. (look at a city, or as an engineer, a modern car. Just because transmission and so on is computer controlled now, does not mean that the Model T Ford required it)
2)the various parts of the system might have been for something else formerly. examples of this, are things like flies wings, which were originally gills, then heat exchangers, and now wings.
3)Things that seem to be irreducably compley might not actually be so, for example, the famed mousetrap example that creationists love to cite, is actually reducable (brilliant link that, by the way)

So I have to remark on your assertion that each mutation will aid survival in comparison to the individuals without it. It seems more likely that each mutation will rather hinder the survival of the individual unless the whole new system is present (which is what I was assuming), in which case the 1:1,000,000 odds are correct, and, about the time there are 9 mutations floating around the gene pool, 1/3 of the individuals will get be defective out of the box.

the number of harmful mutations is something like 2.6 per 1000. all of these mutations will be cut out by natural selection. most of the rest of the mutations will be neutral, and some will be good. the good ones will be preserved.

I also have a hard time swallowing that Great Danes and Chihuahuas are different species, and reconciling your reasoning with your implication that I’m not already a different specie than those people on another continent.

species are two groups of animals which cannot breed, whether this is premating or postzygotic is irrelevant really, because as soon as that barrier is in place genetic drift will split them apart so they can no longer breed even if they fir one another's bits (which danes and chihuauas don't)

Isn’t assortative mating properly considered a mechanism that results in the isolation of gene pools, rather than a sign that there is a a new specie?

as outlined above, this leads to the formation of species.

Have any assortative mating experiments with insects included artificial insemination to test for genetic incompatibility after 500 (or 1,000 or whatever) generations? Perhaps that was buried in the links above and I missed it? It would go a long way to closing the loop (would also take some teensy-tinesy stirrups...).

no need for AI. speciation has already been observed in drosophila (fruitfly) ... breeding the different subspecies produces sterile offspring. there are numerous other examples of insect speciation, such as mosquitoes in the london underground.

 

[chilehed]

but I've been thinking about this, of course. sorry to hear you were sick, glad to hear you're mending (both of you).

I'd like to see that bit on the mousetrap, but it's not a live link. Could you please post the url?

Sorry, gotta disagree with you on the car thing. Take GM's displacement on demand sytem, for example. We tried it about 25 years ago, but it was an abject failure. In order to make it work we needed improvements in control hardware and software, sensors, materials, manufacturing processes, etc, etc,...each of which in turn was the result of dozens of other improvements. And the analogy fails just at the key point, because those improvements were able to happen in different industries and products and we, in effect, gene-spliced them into our own product. It really is an unreducable system, trust me, I was there.

Yep, there it is in the link - speciation in fruit flies. I still find it a stretch to get from there (a new species that is little discernable from its predecessor) to gills morphing into working jaws with teeth. It seems to me that you're postulating forms for which there is no evidence.

Not to beat a dead horse, but defining species in the way you describe is just silly. The obvious conclusion would be that prior to Columbus, people in the Americas were different species than those in Europe.

You've given me lots to think about - thanks. As you can see, my posting frequency is rather sedate, both because of my work and my desire to not come back with half-baked replies. As it is, I'm now much less disinclined to believe in evolution (but of course, even if I was fully convinced I'd still be a creationist - just not a YEC). Man, some of their arguments are SO half-baked.

I'm wondering what your background is, education, major, anything you care to divulge.

We'll discuss things again, I hope.

 

[Data]

Not to beat a dead horse, but defining species in the way you describe is just silly. The obvious conclusion would be that prior to Columbus, people in the Americas were different species than those in Europe.

This isn't what he was saying, as the difference is geological instead of biological, but that given enough time people in the Americas could become a different species. The differences between races show the beggining of seperation, but the amount of time is not nearly enough to seperate the two into more than one species.

On the chihuauas and great danes, if they were found like that in the wild they would be classed as two different species.

 

[Jet Black]

I'd like to see that bit on the mousetrap, but it's not a live link. Could you please post the url?

sorry abuot that.

http://udel.edu/~mcdonald/mousetrap.html

 

[Philosoft]

Not to beat a dead horse, but defining species in the way you describe is just silly. The obvious conclusion would be that prior to Columbus, people in the Americas were different species than those in Europe.

That's not what he meant. The barrier preventing breeding between species is biological. Even that, however, is a flawed standard - horses and donkeys for example (though the offspring are sterile). In any case, get used to the imprecision in taxonomy. Because living things follow much more of a continuum than most of us are aware, there won't be taxonomic agreement until genome-mapping becomes widespread.

 

[Jet Black]

buIt seems to me that you're postulating forms for which there is no evidence.

I will let someone else go over the fossil/animal record. but what about all the forms where there is evidence? The problem is, that your argument just relies on "I can't imagine how it would happen" rather than "it can't happen because"

 

[chilehed]

I neglected to mention that, even after all those technologies were available for the DoD valvetrain, it still took millions of dollars worth of testing and integration work to make it work right.

The mousetrap link is very clever indeed, thanks.

Now that I understand that we agree that the barrier must not be merely geographic (or temporal), I have one less objection. And the drosophila test confirms genetic drift.

I still take issue with part of what Dobzhansky said, though. Horses and donkeys? Yep, two species - mules are sterile. I’ve heard rumor, however, of a successful Dane/Chihuahua mating involving a particularly receptive female Dane and a male Chihuahua who figured out how to use a chair. If the offspring were fertile (which they probably were), then I’d vigorously disagree that they are two species. We’ll just have to agree to disagree on that one (I’ll still respect you in the morning).

I will let someone else go over the fossil/animal record. but what about all the forms where there is evidence? The problem is, that your argument just relies on "I can't imagine how it would happen" rather than "it can't happen because"

You misunderstand; I wasn’t making an argument. I was merely saying that I’m not fully convinced YET that this actually happened, because a sufficient case hasn’t been made to me. No one’s to blame, I’m not the center of the universe and there’s only so much one can learn in a single lifetime. There’s lots that I don’t understand or can’t imagine, yet know is true. I’m sure that this forum will provide ample opportunity for me to catch up on the fossil record. My recent conversion to Catholicism taught me that I should have learned about it from Catholics rather than Protestants (you see the parallel).

For the present I don’t see a fundamental reason why major changes in physiology couldn’t occur as a result of the accumulation of mutations, any more than there’s a fundamental reason why you couldn’t open up a box of 1 million loose black and white marbles and find them segregated by color. It’s not a violation of the 2nd Law (statements to the contrary notwithstanding), it’s just very improbable.

Thanks again.

 

[Gracchus]

Sorry, gotta disagree with you on the car thing. Take GM's displacement on demand sytem, for example. We tried it about 25 years ago, but it was an abject failure. In order to make it work we needed improvements in control hardware and software, sensors, materials, manufacturing processes, etc, etc,...each of which in turn was the result of dozens of other improvements. And the analogy fails just at the key point, because those improvements were able to happen in different industries and products and we, in effect, gene-spliced them into our own product. It really is an unreducable system, trust me, I was there.

The elements are all there: Variation, competition, selection, hybridization (which often produces new, and fertile species in plants), extinction...

You might find interesting: "Without Miracles: Universal Selection Theory and the Second Darwinian Revolution" by Gary Cziko. (c) 1995 Massachusetts Institute of Technology

It seems that evolutionary principles are not just for biology. Science itself evolves.

 

[Data]

chilehed, I don't have any links at the moment, but there have also been fertile mules.

 

[WayMan]

The gread dane has been bred by selective breeding, it's exactly the same with the Chihuahua. They are the same species. There are differences in all species of birds and mamals, where there is a slight phisical difference within a species that is confined to a certain area, this population is usualy described as a sub species, there are many sub species of peregrine falcons, all with their own latin name. It could be argued that these sub species are the beginings of seperate species, and it seems obvious to me that this is the case.
Many kinds of hybrids can be bred with the use of artificial insemination, some of these are fertile and some are not, but I have found that birds from "similar" species, are more often than not fertile.

Birds do not cross breed in the wild because of a phenomemon known as imprinting. A young bird will become sexually attracted to the species that rears it, for example if a bird is reared by a human, it will try to have sex with humans when it is sexually mature. It is this unusual trait that birds posess that keeps the wild species pure. When a sub species eventually develops marked physical differences, the young produced will only be physically attracted to their immediate group, when this happens this will lead to a completely new species.
There are only two species of birds that do not seem to be affected by the phenomenon of imprinting, these species are the parasitic cow bird, and the cuckoo, how do they know?

BTW this is my speciality http://website.lineone.net/~highlandfalcons/

 

[lucaspa]

Where can I find out more about the !Kung, please?
People are always talking about needing a large group of individuals to reestablish a population because oterwise the gene pool will be too small?

First, the !Kung:
Am J Trop Med Hyg 1994 Oct;51(4):460-5
Low prevalence of human T lymphotropic virus type I in !Kung San in Bushmanland, Namibia. Steele AD, Bos P, Joubert JJ, Evans AC, Joseph S, Tucker L, Aspinall S, Lecatsas G

1: Ann Hum Genet 1979 May;42(4):425-33
Red cell adenosine deaminase (ADA) polymorphism in Southern Africa, with special reference to ADA deficiency among the !Kung.
Jenkins T, Lane AB, Nurse GT, Hopkinson DA

Am J Phys Anthropol 1988 Nov;77(3):303-19
Fitness and fertility among Kalahari !Kung.
Pennington R, Harpending H

Am J Hum Genet 1987 Dec;41(6):1132-44
Globin gene-associated restriction-fragment-length polymorphisms in southern African peoples. Ramsay M, Jenkins T

That need for a large population simply isn't right. It's simply that humans have 1) the incest taboo, so they think you need a large population to avoid incest and 2) people won't accept the "high" number of birth defects, so the population has to be large enough to avoid that.

However, those are cultural requirements, not biological.

 

[lucaspa]

My work is with automotive engines, not nearly as complex a system as biology (by what, a few dozen orders of magnitude? if I was REALLY smart I could’ve majored in something else...) but enough to give me an education in how a (supposedly) simple change to one subsystem component in a complex system frequently requires changes to seemingly unreleated subsystems in order to keep the whole think from crashing. So I have to remark on your assertion that each mutation will aid survival in comparison to the individuals without it. It seems more likely that each mutation will rather hinder the survival of the individual unless the whole new system is present (which is what I was assuming), in which case the 1:1,000,000 odds are correct, and, about the time there are 9 mutations floating around the gene pool, 1/3 of the individuals will get be defective out of the box.

I know you can modify the carburetor, gear ratios, thickness of the brake pads, etc, without crashing the whole car. So your analogy won't work.

I also have a hard time swallowing that Great Danes and Chihuahuas are different species, and reconciling your reasoning with your implication that I’m not already a different specie than those people on another continent. Isn’t assortative mating properly considered a mechanism that results in the isolation of gene pools, rather than a sign that there is a a new specie?

"Isolated gene pools" is a new species. As long as the populations don't mate when they could, you have an effective new gene pool. If that is by mate selection or genetic incompatibility, the result is the same: new species.

I did not imply that you are a different species from H. sapiens on other continents. Let's try the definition of biological species again:
A species is a group of individuals fully fertile inter se, but barred from interbreeding with other similar groups by its physiological properties. (producing either incompatibility of parents, or sterility of the hybrids, or both). (Dobzhansky 1935)

Do you have any physiological properties barring you from interbreeding with humans on other continents?

On the other hand, chihuhuas and Great Danes have a physiological property -- gentical incompatibility -- which is a bar. While a male chihuahua can mount a Great Dane (by using the slope of a hill to get into position), even if the male Great Dane genital can penetrates the female chihuahua, the resulting size of the pups will kill her.

Have any assortative mating experiments with insects included artificial insemination to test for genetic incompatibility after 500 (or 1,000 or whatever) generations? Perhaps that was buried in the links above and I missed it? It would go a long way to closing the loop (would also take some teensy-tinesy stirrups...).

3. JM Thoday, Disruptive selection. Proc. Royal Soc. London B. 182: 109-143, 1972.

I’ll mull this over some more, thanks. I wish I had the time to take a class...perhaps you could suggest some decent texts on the subject, suitable for an engineer but not too advanced?

Douglas Futuyma, Evolutionary Biology, 1998 (may be a later edition now).

 

[lucaspa]

Sorry, gotta disagree with you on the car thing. Take GM's displacement on demand sytem, for example. We tried it about 25 years ago, but it was an abject failure. In order to make it work we needed improvements in control hardware and software, sensors, materials, manufacturing processes, etc, etc,...each of which in turn was the result of dozens of other improvements. And the analogy fails just at the key point, because those improvements were able to happen in different industries and products and we, in effect, gene-spliced them into our own product. It really is an unreducable system, trust me, I was there.

From what you say, it was reducible. That is, the different subsystems worked at what they did, but not for what you wanted to use it for.

What you did is called "exaptation" in biology. That is, you took systems that worked for something else and now had them do a new task. This is one way to get complex systems by Darwinian selection.

Insect wings are a good example. They started out as gills, but were exapted as heat exchangers because of the blood flow. They got larger and thinner to become more efficient heat exchangers. Then, at the size that is most efficient to be heat exchangers, that was also the size at which you get the first lift! Voila! Wings! But they didn't evolve as wings. They evolved as heat exchangers that could then be used, already whole, as wings.

"Not necessarily a wing" in Bully for Brontosaurus, pg. 139-151, 1991.

Yep, there it is in the link - speciation in fruit flies. I still find it a stretch to get from there (a new species that is little discernable from its predecessor) to gills morphing into working jaws with teeth. It seems to me that you're postulating forms for which there is no evidence.

What is the biological reality? Species. That's all there is. Just species. Once you get new species thru natural selection and have new characteristics, you are done. The appearance of more major changes is simply multiple speciation events spread thru time. You don't get gills morphing into jaws, not how it worked. But you do get jaw bones becoming middle ear bones, and this transition is documented from species to species in the fossil record. You also get fins morphing into legs and legs morphing into flippers. Or you can look at cormorants and penguins today and see some of the stages in the morphing of wings to flippers.

The point is that it doesn't happen all at once. Just like you didn't go from a Model T Ford to a Thunderbird all in one step.

Not to beat a dead horse, but defining species in the way you describe is just silly. The obvious conclusion would be that prior to Columbus, people in the Americas were different species than those in Europe.

Nope. No physiological barrier, as the Europeans amply demonstrated as soon as they got to the Americas! However, if you ever see the movie The Gods Must Be Crazy look at how the Englishwoman and the !Kung male view each other. Not as possible mates. That is the beginning of reproductive isolation. In contact but a physiological barrier -- appearance.

 

[lucaspa]

The gread dane has been bred by selective breeding, it's exactly the same with the Chihuahua. They are the same species.

Not necessarily anymore.

It could be argued that these sub species are the beginings of seperate species, and it seems obvious to me that this is the case.

So we only disagree how far down the road to speciation the Great Dane and chihuahua have come, since they are subspecies by your view. Have they gone far enough to move out of subspecies to separate species?

Are you familiar with the concept of a Ring Species? Dogs are at least a rign species.

Many kinds of hybrids can be bred with the use of artificial insemination, some of these are fertile and some are not, but I have found that birds from "similar" species, are more often than not fertile.

The Grants have a recent paper on that in regard to the Galapagos finches. I'll try to find it. As I recall, the F1 hybrids were not as fertile as the pure stock.

 

[chilehed]

That need for a large population simply isn't right. It's simply that humans have 1) the incest taboo, so they think you need a large population to avoid incest and 2) people won't accept the "high" number of birth defects, so the population has to be large enough to avoid that.

Fair enough. I was referring to the genetic stuff, not cultural taboos, but if my understanding of the numbers is wrong, I stand corrected. That's why I'm here.

I know you can modify the carburetor, gear ratios, thickness of the brake pads, etc, without crashing the whole car. So your analogy won't work.

I don't think anyone's saying that ANY change constitutes a new species. Rejetting a carb or changing the brake pad compound may be as minor as differences in eye color, but if you try to run diesel fuel in your spark-ignition engine you'd better re-engineer 90% of the rest of the engine.

What you did is called "exaptation" in biology. That is, you took systems that worked for something else and now had them do a new task. This is one way to get complex systems by Darwinian selection.

Well yes, these systems worked in their individual applications, but none of them was a direct plug-in. They all had to be modified to some extent. It's rather like having all these mutations accumulate in the genome, but before they can really work together they all have to simultaneously mutate one last time at the last mating. I'll mull that one over, though, I find it compelling.

Creationists usually demand that EVERY feature be intermediate between the ancestor and descendent, while evolutionists say that transitionals are mosaics, having some features of the ancestors and some of the descendents.

What did you mean by that?

I'll try to find the book by Futuyma. And no, what is a ring species?

The Gods Must be Crazy - my FAVORITE source of information on the !Kung.

There's more on my mind, but I gotta go. I've earned a reputation for posessing a compulsive need to get the last word in, so if I don't post to this thread again it's just because I need some exercise. I'll keep watching.

Blessings. The Lord smile on you.

 

[lucaspa]

if my understanding of the numbers is wrong, I stand corrected. That's why I'm here.

Any random pair from a population has about 75% of the genetic variation of the population. So, the first few generations will have a lot of individuals die of lethal recessives, if the fertility rate is decent you will be able to get a whole new population.

I don't think anyone's saying that ANY change constitutes a new species. Rejetting a carb or changing the brake pad compound may be as minor as differences in eye color, but if you try to run diesel fuel in your spark-ignition engine you'd better re-engineer 90% of the rest of the engine.

But how about if you run 10% ethanol in your engine? Not much change required. Then 20% ethanol, then 30% ethanol, then 40% ethanol etc. You make the changes in steps, not all at once. Each step you have to modify a little, but not the whole thing.

Now remember, the steps accumulate. So by the end of the steps you have modified the engine 90% from the original, but only 2% from the last step.

Well yes, these systems worked in their individual applications, but none of them was a direct plug-in.They all had to be modified to some extent.

Modified to get optimum preformance, right? But evolution doesn't require optimum performance in one step. When the modified gills were used as heat exchangers, they didn't have to work optimally as heat exchangers in the first generation; just better than no heat exchangers at all. The optimization can then take place in slow steps, with modifications. Similarly, in going from heat exchanger to wing, the wing did not have to function optimally that first generation. The insect didn't need to fly for hours at a time, just get off the ground a little to find a little more food or avoid a predator better.

Let's look at aviation. When the Wright Brothers exapted glider wings, car seats, and auto engines to a powered airplane, how long did the first flight last? Did it have to last hours at a time or carry 10 people? No. Instead, the airplane went thru several modifications to become optimized. Then when turbine engines were exapted for airplanes, did the wings need to be swept and the tail surfaces exact for jet flight? No. All those came later.

What you are doing is trying to anticipate optimization in one step. But evolution doesn't need to. As long as it's better than the previous, that's enough. Later generations can take care of optimization.

What did you mean by that?

Just what I said. When Duane Gish looks for an "intermediate", he wants all features to change smoothly and at the same rate from one species to another. He wants partial feathers and a partial wishbone and a shortened tail all together in his "intermediate" between reptile and bird. So to him Archeopteryx is not an intermediate or transitional.

Instead, there is no reason that all features have to change at the same rate or that we will find organisms intermediate in all of them all the time (altho there are examples of intermediates in all features at different rates). How fast a feature is modified depends on the selection pressure and the variations presented to natural selection. Neither of those is uniform across all features.

So what we get are intermediates that have some features of both the ancestor and descendent. In Archie we have a tail (reptile), teeth (reptile), clawed fingers (reptile), feathers (bird), hollow bones (bird), and a wishbone partly between reptiles and birds. Archie represents an intermediate.

In the hominid lineage, the Buia fossil has a skull that is long and oval, pointed at the back, and has massive browridges, all features characteristic of Homo erectus, as is the small brain capacity. The skull differs from erectus is in the parietal bones, which form the curved sides and top of the skull. They are much wider at the top than those of H. erectus and are typical of Homo sapiens. So, many features of H. erectus, but a few features not found in erectus but found only in H. sapiens. Buia is a transitional between erectus and sapiens.

The Gods Must be Crazy - my FAVORITE source of information on the !Kung.

The most entertaining, at any rate.