Evolution for Drotar

[lucaspa]

Let me be honest: this is my first debate over evolution since I learned it. I might, and probably will lose. But as long as I learn more, it doesn't bother me.

Let me be equally honest. This is NOT, NOT, NOT a debate! Did I emphasize the "not" enough?

Debates are sporting events to decide who is the best debator. What we are doing is discussing evolution and creationism to figure out how the universe works.

The universe is what it is, no matter who the judges decide the winner of a debate is.

Edited for embarrassing typo

 

[ifriit]

Let me be equally dishonest.

(emphasis mine)

?

 

[lucaspa]

Here's what I'm talking about:

People use, as proof for evolution more than anything, that our appendix shrunk because we didn't eat raw meat and didn't need it anymore as we started cooking our food. Okay, what the heck? Shrinking appendix because we didn't need it any more: Natural selection, or use and disuse?

People use the appendix as evidence for evolution? Really? Since when? I've never seen that before.

Vestigial organs in general are what I'm talking about.

Now, this I've heard.

Let's start with the appendix. Sometimes terminology gets very loose in discussions, even among scientists. It's because the looseness is often shorter than the full descriptions. And sometimes this can confuse you, as it did above. The idea is to look BEHIND the loose terminology to figure out what is really being said and what is really happening, not take what is an apparent contradiction at face value until you test it.

Now, the appendix as a conscious entity hasn't done anything. The entity isn't conscious, and there's no way for IT to decide its size from generation to generation.

Instead, what happens is that people born with smaller appendices do just as well as those born with larger ones. The selection pressure for a large appendix is gone, but the metabolic price to make one is still there. So now a large appendix has a slightly negative fitness compared to a smaller appendix. There may even be a larger disadvantage in that a large appendix may be more susceptible to infections. I say "may", but we are exploring Darwinian scenarios here.

So, the proportion of people in the population is going to slowly increase because of selection, not because of disuse.

The most common illustration in defense of the theory is a series of horses that gradually lose a toe at a time as time goes on. I asked, did having one more toe cuase group A to cease living because the new more evolved species had one less? Did they become extinct because the new species had one less toe? They all responded, no, it hindered their running and so eventually they didn't need it. Is that loss of one toe THAT substantial so as to wipe out the preexisting population? Sorry, I'm not going to buy what I'm being sold here.

Explain thus much and I'll respond in turn. TTYL Jesus loves you!

Your respondents seem to be adhering to Lamarckism, not Darwinian evolution. For the horses we have an original population of 5 toed Eohippus (old name, but it's shorter than hyracatherium) who lived in a marshy, forest environment. The 5 toes enabled ground pressure to be spread over a larger area and thus better footing IN THIS ENVIRONMENT.

One population of eohippus either migrated to a more arid climate or the area they were in had a climate change to a more arid climate. The ground became drier and firmer. Those individuals with fewer toes but a larger center toe could run better than the 5 toed IN THIS ENVIRONMENT. (Notice I stress that everything is relative to the environment). Thus, the lucky individuals could better avoid predators and did better, having more offspring. Eventually, over many, many generations, this population of Eohippus is 4 toed and a new species.

Back in the orginal homeland, the population living in the marshy forest is doing fine with its 5 toes.

 

[lucaspa]

Guys, can you do me a favor and refrain from replying. We don't want to overwhelm Drotar. I can do that all by myself, thank you.

If I miss something important that he needs to know, then post it. In the meantime, please let us continue this discussion ourselves.

 

[lucaspa]

(emphasis mine)

?

embarrassing typo. what happens when the grad student interrupts a post. Thanks for catching it.

 

[Drotar]

"Let me be equally honest. This is NOT, NOT, NOT a debate! Did I emphasize the "not" enough?

Debates are sporting events to decide who is the best debator. What we are doing is discussing evolution and creationism to figure out how the universe works.

The universe is what it is, no matter who the judges decide the winner of a debate is."

Agreed. Accept my apologies, I made a typo too. Of course, I don't think my typo was as awkward as the honest-dishonest one, but hey, who's counting?

"Guys, can you do me a favor and refrain from replying. We don't want to overwhelm Drotar. I can do that all by myself, thank you."

Oh you're good. Snuck that comment in there did you now? You probably are. I'm not so arrogant as to claim that I'm going to overwhelm you though. I'm a student and I understand my limits.

On to the good stuff:

"People use the appendix as evidence for evolution? Really? Since when? I've never seen that before."

Oh man, you don't even know. They use that example like CRAZY. See, many evolutionists think of it as the law of use and disuse. The problem is that in high school, evolutionists don't know thir own theories. They talk about humans in the year 3000 having pale skin and thinner bodies because they do everything in doors. NOT natural selection man! Oh well, now that I'm done ramblig I'll get off my soap box...

"Instead, what happens is that people born with smaller appendices do just as well as those born with larger ones. The selection pressure for a large appendix is gone, but the metabolic price to make one is still there. So now a large appendix has a slightly negative fitness compared to a smaller appendix. There may even be a larger disadvantage in that a large appendix may be more susceptible to infections. I say "may", but we are exploring Darwinian scenarios here.

So, the proportion of people in the population is going to slowly increase because of selection, not because of disuse."

Nope. Nah-ah.

I do like what you did with the last sentence. You mentioned an increase in the contribution of certain alleles into the gene pool. But you did not mention a decrease. And that's my problem. There would be an increase, sure, but as for people with larger appendices, would they start becoming extinct as a result? No. It would have an effect but every one misunderstands me in this aspect:

The effect would not be substantial enough to cause the dying off of the pre-existent group A faster than they can reproduce. You see, from a Darwinian perspective, if the rate of allele contribution of the old allele is still being introduced faster than the rate of animals dying before adulthood, then whether it is more or less evolved is not the issue. The issue is that if the birth rate supercedes the death rate before reproduction, then the contribution of the old alleles will still keep rising.

The issue is, is having a functional appendix going to cause the death rate in group A to supercede the birth rate? And don't answer what best suits you: answer logically. ABSOLUTELY NOT!

"Your respondents seem to be adhering to Lamarckism, not Darwinian evolution. For the horses we have an original population of 5 toed Eohippus (old name, but it's shorter than hyracatherium) who lived in a marshy, forest environment. The 5 toes enabled ground pressure to be spread over a larger area and thus better footing IN THIS ENVIRONMENT.

One population of eohippus either migrated to a more arid climate or the area they were in had a climate change to a more arid climate. The ground became drier and firmer. Those individuals with fewer toes but a larger center toe could run better than the 5 toed IN THIS ENVIRONMENT. (Notice I stress that everything is relative to the environment). Thus, the lucky individuals could better avoid predators and did better, having more offspring. Eventually, over many, many generations, this population of Eohippus is 4 toed and a new species.

Back in the orginal homeland, the population living in the marshy forest is doing fine with its 5 toes."

Same issue here as last time. Sure they'll do better now. But environment change or not, is having one less toe going to make the death rate before reproduction (and thus contribution of old alleles) into the gene pool going to supercede the birth rate, thus causing them to die out. Having an extra toe ain't gonna do that dude.

Evolution isn't just about an increasing of new alleles. The brightest evolutionists forget that the old allele contribuion has to DECREASE as well. And that can happen only by having a death rate before adulthood faster than the birthrate. Evoluion isn't just about the birth of the new, but about the death of the old as well. TTYL Jesus loves you!

 

[Drotar]

The problem with evolution, is that it's not pragmatic. Not realistic.

Things don't die out that easily. Things going extinct in the natural world, as a result of competetion of resources, hich in reality isn't THAT competitve, are HARD TO FIND.

 

[lucaspa]

I have to say that here's the problem:

If there is a transition between one species to another (which has never been uncovered), then during those five or six generation or however long it takes, those new animals with changes that are purely seminal (not quite developed as of yet), will be at a DISadvantage to the pre-existing population.

As someone pointed out, the first claim of no transitional fossils is not correct.

Let's address the second claim, that of disadvantage.

New species arise in 3 general ways (there are a couple of minor orther ways we can discuss later):
1. ALL the population transforms slowly over time in response to a new environment.
2. A PART of the population is isolated by geography and faces a different environment in the new habitat.
3. A PART of the population exploits a new ecological niche, which is a new environment.

Because of that, they will never get to the point where their new traits are fully developed. Because through many generations, that new species will be at a DISadvantage possessing not-funcitonal traits, and expending that energy loss.

OK, let's look at this.

In 1 above, since all the population is facing a changing environment, the old trait is not good anymore because it evolved for the old environment. So the new trait can replace it because, even tho it is only partly formed, it is better than anything else the population has to face the new environment.

In 2, the new trait is not in competition with the old because the populations are geographically separated and the new trait is better than anything the isolated population has to face the new environment with.

In 3, the part of the population is separated from the rest by the new ecological niche and the new trait is better than anything the population has to face the new environment.

So that deals with the "partially developed trait". In each case the new trait can be partially developed because it is not competing with the old trait. In in each, the old trait doesn't fit the new environment so even a partially developed trait is going to be fine. There's no competition from any of the old traits.

You see Drotar, speciation isn't like having part of the population wake up one morning and be a new species but look just like the old. Speciation occurs when several of these new traits are gradually added to the population over many generations so that, eventually, the population is different from the original. In other words, instead of having speciation and then changing, the population changes and the result of that change is a new species.

 

[Drotar]

No, I understand what speciation is.

I couldn't explain what I intended to say very well. The grunt didn't suffice huh?

My question, there is a process of developing into a new species, is there not? The new species forms as a result of the transition.

I forgot what its called. Its not the bottleneck effect, but something with 'survivor' or 'pioneer' in in the term. You offered the explanation that there would be a separation of one species.

That's right, I think it's called the colony effect or something.

Problem, in the real world, I mean the natural world, separation and colonization is EXTREMELY rare. The birds on the Galapagos islands are the only example I can think of. If animals are fit and evolved to the environment where they are in, they don't just pack up and leave.

The examples posed are usually a result of man's interference, or simply not realistic. The example REQUIRES a new environment. Animals stay where they have the best chance of survival.

Unless you want to suggest that the very components of the air and the atmospheric conditions change frequently.

If you suggest these fluctuations of the components of the atmopshere and its conditions change frequently, may we move on to carbon-14 radiometric dating?

My other post remains BTW. TTYL Jessus loves you!

 

[lucaspa]

"Guys, can you do me a favor and refrain from replying. We don't want to overwhelm Drotar. I can do that all by myself, thank you."[/I]

Oh you're good. Snuck that comment in there did you now? You probably are. I'm not so arrogant as to claim that I'm going to overwhelm you though. I'm a student and I understand my limits.

Sorry, Drotar, I was poking fun at myself. I am known for my long and many posts. It wasn't the disparity between us I was talking about, but my own long-windedness.

On to the good stuff:

"People use the appendix as evidence for evolution? Really? Since when? I've never seen that before."

Oh man, you don't even know. They use that example like CRAZY.

Then no wonder you see problems with evolution. It appears that you've gotten a pretty poor description of evolution.

"Instead, what happens is that people born with smaller appendices do just as well as those born with larger ones. The selection pressure for a large appendix is gone, but the metabolic price to make one is still there. So now a large appendix has a slightly negative fitness compared to a smaller appendix. There may even be a larger disadvantage in that a large appendix may be more susceptible to infections. I say "may", but we are exploring Darwinian scenarios here.

So, the proportion of people in the population is going to slowly increase because of selection, not because of disuse."

I do like what you did with the last sentence. You mentioned an increase in the contribution of certain alleles into the gene pool. But you did not mention a decrease. And that's my problem. There would be an increase, sure, but as for people with larger appendices, would they start becoming extinct as a result?

Drotar, so far we are WITHIN a species. Notice I didn't talk about alleles, but about INDIVIDUALS. Those with smaller compared to those with larger. When I said "the proportion of people with a smaller appendix is going to slowly increase" this has within it the decrease in the larger population.

What is proportion? It is a fraction. If N = the total number of individuals in the population, L = the number of individuals with a large appendix and l = the number of people with a small appendix, then the proportion with a large appendix L is going to be L/N. The proportion of people with a smaller appendix "l" is going to be l/N. Since L + l = N, L/N + l/N = 1 It has to if those are the only two choices.

So, as l increases, L decreases.

The effect would not be substantial enough to cause the dying off of the pre-existent group A faster than they can reproduce.

There is no "pre-existing" GROUP. There is only the individuals with a large appendix and those with a smaller one.

You see, from a Darwinian perspective, if the rate of allele contribution of the old allele is still being introduced faster than the rate of animals dying before adulthood, then whether it is more or less evolved is not the issue.

The problem is with your "if". It is not true. In most populations the population is stable. That is, there are the same number of adults from one generation to the next. N is constant. Yes, more are born of both L and l than live to adulthood. HOWEVER, more of the old allele are dying before adulthood than the new allele. That's what SELELCTION is all about. Differential survival and reproduction. More of the l individuals will live than the L individuals.

The issue is that if the birth rate supercedes the death rate before reproduction, then the contribution of the old alleles will still keep rising.

Yes, it would. But that doesn't happen.

The issue is, is having a functional appendix going to cause the death rate in group A to supercede the birth rate? And don't answer what best suits you: answer logically. ABSOLUTELY NOT!

The functional appendix ALONE isn't going to cause the death rate of L to be larger than the birth rate, but the COMPETITION with l will. Remember, the appendix may be functional but the small appendix is JUST AS FUNCTIONAL. BUT, the large appendix is going to have a metabolic cost and a cost of higher disease. Let's do some simple numbers with simple assumptions.

We have 100 people or 50 couples. 90 have large appendix and 10 have small. We'll have the large appendix breed with the large and the small with the small to keep it simple. 45 couples of large and 5 couples of small. Each couple has 5 kids for a total of 250 in the next generation; 225 large but 25 small. BUT, disease kills an average of 150 of them (holding the population stable), so 150/250 = 3/5 of them will succumb to disease. Now, say small appendix is only half as likely to die of disease so only 1.5/5 die of disease.

In our 225 large appendix, 135 will die of disease and 90 will be left. But of the 25 small appendix, only 8 die of disease, leaving 17 small appendix instead of the 10 in the earlier generation.

So, the proportion of large appendix was 0,9 and the small appendix was 0.1. Now, however, the proportion of the large appendix is 90/107 for 0.84 and the small appendix is 0.16. Keep this going generation after generation and soon there will be no large appendix people left.

Same issue here as last time. Sure they'll do better now. But environment change or not, is having one less toe going to make the death rate before reproduction (and thus contribution of old alleles) into the gene pool going to supercede the birth rate, thus causing them to die out. Having an extra toe ain't gonna do that dude.

Yes, it is. That's what selection and fitness in an environment is all about.

Let's try a different example, this time getting food. There's food for only 100 individuals. again we have 90 5 toes and 10 4 toed horses. Again, for simplicity, we have 5 toed breeding with 5 toed and 4 toed breeding with 4 toed and 5 offspring, so 225 5 toed and only 25 4 toed. To make it simple, say that 4 toed animals win at getting enough food. So, all 25 4 toes get enough food. But, since there is only enough food for 100 total, that means that only 75 5-toed survive. So, in the previous genereation we had 225 5-toed born and 90 live. That's a death rate of 130 5 toed. But in this generation, only 75 5 toed lived, for a death rate of 150. So, the number of 5 toed decreases and the number of 4 toed increases.

And that can happen only by having a death rate before adulthood faster than the birthrate.

I see what the problem is. The examples show that all you need is a death rate before adulthood that is greater than the death rate of the other allele, not greater than the birthrate.

 

[Cantuar]

Prof, could you give a bit more detail about the difference between geographical isolation and new ecological niche? Thanks.

 

[Arikay]

And to add to that, can you give a few examples of natural geographic issolation, and how common or rare it is.

 

[lucaspa]

That conclusion was drawn to support what they wanted to see in the fossil record and in evolution.

In a discussion, you have to back the claim with evidence.

The claim that Hyracatherium lived in a different environment from its 4 toed descendent can be independently tested by looking at the other fossils found in the same geological layer as the bones of the horses. You can look at the types of plants, the types of insects, etc, and determine what the climate is like. For instance, finding ferns means the environment wasn't a desert and finding cactus means the environment wasn't a swamp. Those are the two extremes, but it conveys the idea and the intermediate environments can also be looked determined by similar analyses.

Remember, the conclusion was first a hypothesis that had to be tested. If the testing showed the hypothesis wrong, then it is wrong, and "wanted" doesn't cut it in science.

Proving the variations in plant life is even more impossible.

That is even easier. Plants fossilize. More importantly, the POLLEN from plants is pretty plentiful and fossilizes more easily. So, if you find pollen of grasses that live in dry climates, then you infer that the climate was dry. If you find pollen from trees in the layers with Hyracotherium and pollen from trees in the 4 toed descendent, then the inference is that Hyra lived in forests and the descendent lived in grasslands.

The next step is reverse-engineering the foot and the legs. Biomechanical studies will show that the fewer toed version will run faster on firmer ground while the 5 toed version spreads the ground pressure out for a moister ground. Also, the increased stability of 5 toes allows for quicker turns as the animal dodges trees and underbrush while the 4 toed version is faster in the flat.

Please, respect that I am at a disadvantage just having graduated high school and all! Debating with a scientist is hard enough.

Again, you are NOT debating. You are making claims. Everyone is testing those claims and providing information that shows the claims to be in error.

This is how science works. Welcome to my world. You make a claim and then you and your colleagues test that to see if you can show it wrong. In this case we aren't going to the lab ourselves, but testing the claims against what OTHER people have already found: in the lab and in the wild.

 

[lucaspa]

No, I understand what speciation is.

I couldn't explain what I intended to say very well. The grunt didn't suffice huh?

My question, there is a process of developing into a new species, is there not? The new species forms as a result of the transition.

I forgot what its called. Its not the bottleneck effect, but something with 'survivor' or 'pioneer' in in the term. You offered the explanation that there would be a separation of one species.

That's right, I think it's called the colony effect or something.

You are thinking of the Founder Effect. This is when a VERY small population ends up at a new place, such as colonizing a new island. The population is from 1-5 breeding pairs.

This is one of the very minor methods of speciation I didn't mention because it does not happen much. Drosophila (a genus of flies) in Hawaii is an example.

In my examples, both 2 and 3 -- allopatric and sympatric speciation -- take one species and split it into two. You now have 2 species where there was 1. #1 was phyletic gradualism and simply results in the replacement of one population by a new one thru time. IF we had a time machine, we could take the current population into the past and show that it is a different species from the one in the past.

Pesticide resistance in insects is an example of phyletic gradualism. The insects alive today are different from the ones 100 years ago because of their pesticide resistance. However, since we don't have any from 100 years ago to test whether they are interfertile with the ones today, we can't do the experiments and, out of laziness, we keep the same species names.

Problem, in the real world, I mean the natural world, separation and colonization is EXTREMELY rare.

Yes, the Founder Effect is rare. BUT, allopatric and sympatric speciation are very common.

If animals are fit and evolved to the environment where they are in, they don't just pack up and leave.

Not "leave" but expand their range. Let's face it, there are more resources for a population at the edges of the range of the population. So, in search of food, the members at the edge tend to keep moving even further out. This makes it easy for them to get isolated from the main population. Barriers are many, depending on the mobility of the population. For birds, you need things like mountain ranges or seas. For mountain goats, you only need the next valley in the mountains. For shrews, just across the creek will do. Or across the highway.

Animals stay where they have the best chance of survival.

Now, why would they do that? How would they know that where they are gives them the best chance of survival? They have no history. No statistics showing that living on this side of the river increases life expectancy but on the other side decreases it.

Animals move in search of food, and if they end up in place that has a different and not quite as good environment, that's their tough luck.

Unless you want to suggest that the very components of the air and the atmospheric conditions change frequently.

Atmospheric conditions (climate) can change frequently. In California you get 5 weather reports from San Francisco to Lake Tahoe, a distance of just over 200 miles. Five separate microclimates all a bit different.

 

[lucaspa]

Prof, could you give a bit more detail about the difference between geographical isolation and new ecological niche? Thanks.

All this will be from Futuyma, Evolutionary Biology, 1998, pp 42-490. Drotar, this is a good book to get. It will be heavy reading for you, since it assumes education of terms you haven't had. But you can always come and ask us what the terms mean and for help in explaining concepts that you don't get initially.

"Allopatric speciation is the evolution of genetic reproduction barriers between populations that are geographically separated."

For species that don't disperse much, extrinsic barriers can isolate populations on a "microgeographic scale". An example would be segregated habitats in a lake. The deep middle is a different environment from the shallow edges.

Sometimes the species can stay put and the barrier comes to them. For instance, when the Isthmus of Panama rose, it split many marine populations into Pacific and Carribean populations. This would include mollusks who don't move. Many of these have diverged into separate species (reference on request). This emergence of a barrier and the splitting of a population is called "vicariant speciation. "Vicariant species of tulip poplarin eastern Asia and eastern North America are the remnants of of a once wider distribution across nothern North America and Siberia, where climatic change has made much of the region uninhabitable for these trees."

What we usually refer to is the "colony" mode of allopatric speciation. The major part of this is "peripatric speciation" which is isolation of a sub-population at the periphery of the range of the main population. We can discuss the various ideas of the genetic changes in these populations in more detail later.

"Probably thousands of examples provide evidence for allopatric speciation. Most of these arise from systematists' studies of geographical variation within species and the geographic distribution of semispecies and close related species. There are several classes of evidence for allopatric speciation."

Drothar, before you jump on the "probably", it is not that the evidence is probable and not certain, but the NUMBER of examples is probably in the thousands. Futuyma gives two references, both by Mayr. Both are whole books! One is Systematics and the Origin of Species, 1942 and the other is Animal Species and Evolution, 1963. There are several other references by Mayr on the subject. In addition to several examples in the wild, Futuyma also mentions some lab studies.

Sympatric speciation occurs when a biological barrier to to gene exchange arises within the confines of a randomly mating population in the same geographic area.

Sympatric speciation happens when homozygous genotypes have high fitness on one or the other of two resources and intermediate -- heterozygous phenotypes have lower fitness. This tends to pull the genotypes apart as each is on one or the other resource. A famous example is the apple maggot fly. These flies emerge from pupae in July and August and mate on the host plant; the larvae develop in ripe fruits, and in the autumn drop to the ground, spending the winter as pupae. The original population was hawthorns. However, when cultivate apple trees (related to hawthorns) were introduced in the US, some of the apple maggot flies instead climbed apple trees instead of hawthorn trees. Now there are two species, with different genotypes and that the apple maggot flies on apples mate 3 weeks earlier than the ones on hawthorns, thus isolating them.

There are also some lab studies of Drosophila where sympatric speciation caused partial reproductive isolation.

There is a debate going on in evolutionary biology circles about which mode of speciation -- allopatric or sympatric -- is most prevalent in the wild.

A recent paper discussing allopatric speciation but also discussing sympatric is 6. B Wuethrich, Speciation: Mexican pairs show geography's role. Science 285: 1190, Aug. 20, 1999. If anyone wants, I'll get the PDF file and e-mail it to you.

The article is too long to conveniently post, but I can try in several posts if there is enough interest. Drothar, all public libraries subscribe to Science.

 

[Drotar]

Then no wonder you see problems with evolution. It appears that you've gotten a pretty poor description of evolution.

I wouldn't quite say that about my teacher. If someone else had taught me, I NEVER would have learned that much in class. Any errors or flaws in my posts should be traced back to me alone.

BTW, did you help grade the AP exams for biology? I just received word that I got a 4, which is good news for me, but not something that's going to impress a scholar of your caliber. Just curious if you helped out with that.

Drotar, so far we are WITHIN a species. Notice I didn't talk about alleles, but about INDIVIDUALS. Those with smaller compared to those with larger. When I said "the proportion of people with a smaller appendix is going to slowly increase" this has within it the decrease in the larger population.

What is proportion? It is a fraction. If N = the total number of individuals in the population, L = the number of individuals with a large appendix and l = the number of people with a small appendix, then the proportion with a large appendix L is going to be L/N. The proportion of people with a smaller appendix "l" is going to be l/N. Since L + l = N, L/N + l/N = 1 It has to if those are the only two choices.

Not again! Equations! Drat!

Well, that looks like some aspect of the Hardy-Weinberg theorum. (Which is the reason I didn't get a 5 on the exam BTW). I couldn't stand all the math. Remind me before this discussion is over to bring up the five points of the theory. That's another case again evolution.

Agreed, however you left out a vital assumption. That resources are so limited that animals are literally starving to death- BEFORE the reproductive age. Animals aren't the only ones reproducing. Plants are too. The food chain, without man's interference, is relatively stable. At the rate which animals consume, the naturally dense forests reproduced to accomodate the life it held. Usually, if you really think about it, you really don't see animals lying on the floor or in trees starving to death. There's food all around them. In theory, evolution i logical. In reality, it's not practical and applicable. It's too simple- there are billions of factors in teh enviornment and diseases and genetics and whatever that can alter the results in a HEARTBEAT. Fact: I never doubted the possibility for adaptation to function on a relatively small scale, WITHIN a species due to alleles. I did doubt speciation. And even if you DID prove it was possible, you can't prove that THAT was what actually happened. What, are you going to use carbon-dating?

Didn't you just make the claim that atmospheric conditions are extremely unstable? (And I"m not just talking about the climate now- you gotta give me a little credit.)

The problem is with your "if". It is not true. In most populations the population is stable. That is, there are the same number of adults from one generation to the next. N is constant. Yes, more are born of both L and l than live to adulthood. HOWEVER, more of the old allele are dying before adulthood than the new allele. That's what SELELCTION is all about. Differential survival and reproduction. More of the l individuals will live than the L individuals.

That's where we differ. The claim that N is constant. If given time, the population expands. Now here's the issue: Is the difference between the death rates before the reproductive age of L-I GREATER than the expansion rate of the steadily growing population, which is N.



Yes, it would. But that doesn't happen.

I think it does. If we're still talking about the contribution of old alleles increasing, DESPITE the fact that they have the proper number of toes on each foot (hoof, sorry), then I maintain my old position. Change or not, the extra toe isn't going to be so substantial so as to wipe out group A. Forests, plains, swamp, whatever. It's a stinking toe man. Look past the theory and look into practicality. Pragmatism.

The functional appendix ALONE isn't going to cause the death rate of L to be larger than the birth rate, but the COMPETITION with l will. Remember, the appendix may be functional but the small appendix is JUST AS FUNCTIONAL. BUT, the large appendix is going to have a metabolic cost and a cost of higher disease. Let's do some simple numbers with simple assumptions.

Whoa, wait a sec. So you're saying that our appendix is just as functional? It is my assumption that evolutionists claim the appendix to be a vestigial organ. I am right, right? I always thought that the appendix served little known purpose as of now. Are you going against these medical claims?

The purpose of the appendix was to buff the immunity against foreign pathogens in the digestive tract, particularly with uncooked food. Now, that sure as day says to me that that would PREVENT disease. Thus, though a higher metabolic cost, a LOWER rate of disease and a HIGHER rate of survival. Something doesn't add up. I stink at math, but I know there's a problem here.

Yes, it is. That's what selection and fitness in an environment is all about.

Let's try a different example, this time getting food. There's food for only 100 individuals....

Charge that. I understand natural selection (better than some classmates anyways- if that's of any consolation). I've got little discrepancy with the theory itself. Simply in the fact that it's not applicable in practice. IMHO, the shoe DOESN'T fit.

Please don't get upset that I cut your quote short here, but I undrstand what you're saying. It's the part where there's only food for 100 individuals. Go outside. Take a photograh of an owl leaned against the trunk of a tree starving to death, or a mouse cuddled in the fetal position because it can't find any food in the forest. I know I'm sounding silly. There's not just enough food for 100 individuals. It's not that simple-there are millions of factors. Evolution works only if you give overly-simplified examples.

My point is that you very, VERY rarely see animals starve to death in the wild. Resources aren't THAT limited. Even if they WERE, who's to say a toe did that. Are we going to blame an animal dying on THAT? Or on some other factors? Who's to say the MORE evolved didn't make it this time? I understand the lines of what you're going to say next, but please understand that my point in asking is merely to emphasize that we cannot successfully predict that stuff, and blame it consistently on a toe. In a metaphysical sense, there's no such thing as chance. Everything happens through a result of causes leading to an effect. Having a functional appendix vs. a non would in theory make a difference, in theory, but in actuality there are millions of contingencies and causes. In practice, we cannot calculate all that causes it. Since the natural population would slowly rise, and since the change is QUITE insubstantial, I would say that also given the biollions of factors, the rate of evolution is way, WAY overexaggerated, if worthy to be considered evolution at all.

Here's another factor: you claim that those with small appendixes require a smaller metabolic input. First, the difference of a toe isn't gonna make that much a difference. The MUCH bigger factor lies in the fact that animals, just like humans, each VARY in metabolic rates. We're assuming that there's one absolute rate and that those with smaller appendices or toes or whatever will survive since there's less energy expenditure. But the assumption is that "If X population remains constant" or "if X (metabolic rate) is an absolute". The theory of evolution must be overly-simplified. A toe isn't the issue, it would still be this here.

I see what the problem is. The examples show that all you need is a death rate before adulthood that is greater than the death rate of the other allele, not greater than the birthrate.

Question: And what of a trait being dominant or recessive? It must be one or the other.

If a trait that encourages survival is recessive, and thus overpowered by the allele for the proper number of toes (this is ridiculous), then shall we say that this SERIUOUSLY complicates the issue? Like, if green eyes caused people to survive better, then STILL over time, considering the number of people with brown eyes in the world, there would be no people with green eyes left. Survival rate or not, if the change is not substantial enough, then dominant alleles will always win. I'm talking over insubstantial traits. Wilikers!



Let me introduce new questions: how does mutualism evolve?

Sheep can't fly, hide, camouflage, jump, or even RUN- their knees buckle. If they fall over, they cannot right themselves. If you don't lead them to grass or water every day, they die because they are incapable to survive without a shepherd. Perhaps I don't understand the theory as I thought, but where does the natural selection therein lie?

TTYL Jesus loves you!

 

[Drotar]

You are thinking of the Founder Effect. This is when a VERY small population ends up at a new place, such as colonizing a new island. The population is from 1-5 breeding pairs.

The founder effect! And I said colony or pioneer effect. How embarasing. Whoops...

This is one of the very minor methods of speciation I didn't mention because it does not happen much. Drosophila (a genus of flies) in Hawaii is an example.

And for what its worth, the bottleneck effect is even less common than the founder. The real-life examples used for the BN effect are a reslt of man's interference.

In my examples, both 2 and 3 -- allopatric and sympatric speciation -- take one species and split it into two. You now have 2 species where there was 1. #1 was phyletic gradualism and simply results in the replacement of one population by a new one thru time. IF we had a time machine, we could take the current population into the past and show that it is a different species from the one in the past.

Part of my problem lies also with taxonomy. Different species? Or variation of the same?

Pesticide resistance in insects is an example of phyletic gradualism. The insects alive today are different from the ones 100 years ago because of their pesticide resistance. However, since we don't have any from 100 years ago to test whether they are interfertile with the ones today, we can't do the experiments and, out of laziness, we keep the same species names.

Laziness? Or a proper understanding of alleles, traits, and variation to species. I think we are a little too trigger-happy at labeling things as speciation.

Not "leave" but expand their range. Let's face it, there are more resources for a population at the edges of the range of the population. So, in search of food, the members at the edge tend to keep moving even further out. This makes it easy for them to get isolated from the main population. Barriers are many, depending on the mobility of the population. For birds, you need things like mountain ranges or seas. For mountain goats, you only need the next valley in the mountains. For shrews, just across the creek will do. Or across the highway.

True, but will that result in speciation, or naturally selected variation within the species?

Animals move in search of food, and if they end up in place that has a different and not quite as good environment, that's their tough luck.

Forgive me if I respectfully disagree. If they wind up in place that they have trouble surviving in, they go back home. They don't tough it out and evolve. For all they know they're dying. Show me an animal that, when posed with a difference in environment, doesn't move to where it is best-suited? If it's cold, they'll find themselves south. They don't stay and grow thicker fur. They go where it's warm.

Atmospheric conditions (climate) can change frequently. In California you get 5 weather reports from San Francisco to Lake Tahoe, a distance of just over 200 miles. Five separate microclimates all a bit different.

I wasn't talking about climate. I understand that there are things called seasons and that sometimes weather changes. You gotta give me a little credit.

I'm talking about conditions in the atsmosphere. There's MUCH more oxygen gas than at the beginning of the world. Let's say, also, a change pertaining to the Van Allen radiation belt. You're a clever guy- you know where I'm going with this. TTYL Jesus loves you!

BTW, thanks for the private debate. Thus far this has been really cool.

 

[Drotar]

All this will be from Futuyma, Evolutionary Biology, 1998, pp 42-490. Drotar, this is a good book to get. It will be heavy reading for you, since it assumes education of terms you haven't had. But you can always come and ask us what the terms mean and for help in explaining concepts that you don't get initially.

"Allopatric speciation is the evolution of genetic reproduction barriers between populations that are geographically separated."

For species that don't disperse much, extrinsic barriers can isolate populations on a "microgeographic scale". An example would be segregated habitats in a lake. The deep middle is a different environment from the shallow edges.

Sometimes the species can stay put and the barrier comes to them. For instance, when the Isthmus of Panama rose, it split many marine populations into Pacific and Carribean populations. This would include mollusks who don't move. Many of these have diverged into separate species (reference on request). This emergence of a barrier and the splitting of a population is called "vicariant speciation. "Vicariant species of tulip poplarin eastern Asia and eastern North America are the remnants of of a once wider distribution across nothern North America and Siberia, where climatic change has made much of the region uninhabitable for these trees."

What we usually refer to is the "colony" mode of allopatric speciation. The major part of this is "peripatric speciation" which is isolation of a sub-population at the periphery of the range of the main population. We can discuss the various ideas of the genetic changes in these populations in more detail later.

"Probably thousands of examples provide evidence for allopatric speciation. Most of these arise from systematists' studies of geographical variation within species and the geographic distribution of semispecies and close related species. There are several classes of evidence for allopatric speciation."

Drothar, before you jump on the "probably", it is not that the evidence is probable and not certain, but the NUMBER of examples is probably in the thousands. Futuyma gives two references, both by Mayr. Both are whole books! One is Systematics and the Origin of Species, 1942 and the other is Animal Species and Evolution, 1963. There are several other references by Mayr on the subject. In addition to several examples in the wild, Futuyma also mentions some lab studies.

Sympatric speciation occurs when a biological barrier to to gene exchange arises within the confines of a randomly mating population in the same geographic area.

Sympatric speciation happens when homozygous genotypes have high fitness on one or the other of two resources and intermediate -- heterozygous phenotypes have lower fitness. This tends to pull the genotypes apart as each is on one or the other resource. A famous example is the apple maggot fly. These flies emerge from pupae in July and August and mate on the host plant; the larvae develop in ripe fruits, and in the autumn drop to the ground, spending the winter as pupae. The original population was hawthorns. However, when cultivate apple trees (related to hawthorns) were introduced in the US, some of the apple maggot flies instead climbed apple trees instead of hawthorn trees. Now there are two species, with different genotypes and that the apple maggot flies on apples mate 3 weeks earlier than the ones on hawthorns, thus isolating them.

There are also some lab studies of Drosophila where sympatric speciation caused partial reproductive isolation.

There is a debate going on in evolutionary biology circles about which mode of speciation -- allopatric or sympatric -- is most prevalent in the wild.

A recent paper discussing allopatric speciation but also discussing sympatric is 6. B Wuethrich, Speciation: Mexican pairs show geography's role. Science 285: 1190, Aug. 20, 1999. If anyone wants, I'll get the PDF file and e-mail it to you.

The article is too long to conveniently post, but I can try in several posts if there is enough interest. Drothar, all public libraries subscribe to Science.

Man, you don't know how much all this is taking out of me. I've spent a long time trying to think of responses.

You must be careful which lab results you read. There was a case where students nad a piece of LIVE coral. The scientists didn't know what they were testing on, but they estimated it to be 14,000 years old!

Please, call me Will. Being called by my last name is awkward.

I didn't see what you were talking about. I do better without examples or illustrations becasue they usually skew my understanding of what we're talking about. Just give me the classic textbook definitions of the two types of speciation. I take it this isn't gradualism vs. punctuated equilibria.

TTYL Jesus loves you!

 

[Drotar]

BTW, don't feel rushed. As a prof I understand you're a busy guy. TTYL Jesus loves you!

 

[Frumious Bandersnatch]

You must be careful which lab results you read.

There was a case where students nad a piece of LIVE coral. The scientists didn't know what they were testing on, but they estimated it to be 14,000 years old!

Since everyone who knows anything about C14 dating knows that it can't be used reliably on marine organisms I assume some creationist just did this to deceive you into thinking there is some big general problem with radioactive dating.

The Frumious Bandersnatch