Evolutionary question, answered

Feb 28, 2012 By Peter Reuell
As one of the first researchers to raise questions about earlier peppered moth studies, Michael Majerus, a professor of genetics at the University of Cambridge, had meticulously designed and conducted the years-long experiment, but died before he was able to publish his findings. Credit: James Mallet

A new paper published in the Royal Society’s Biology Letters journal, shows that early experimental studies of the peppered moth, as taught to many American high school students, are “completely correct,” co-author James Mallet, Distinguished Lecturer on Organismic and Evolutionary Biology, said.

The research is particularly noteworthy, Mallet said, because it settles a decade-long controversy about whether the moths are a good example of natural selection at work.

Though the moths are typically a mottled black-and-white color, scientists in England at the time of Queen Victoria began seeing increased numbers of all-black moths following the start of the Industrial Revolution. Studies later showed that the moths had benefited from the black color because they were better able to camouflage themselves against the trunks of soot-stained trees. Later research also showed that, as air quality improved, the moths’ reversed course, and the number of black insects fell dramatically.

Despite decades of research that showed the moths evolved in response to their environment, doubts began to surface in the late 1990s as some in the scientific community suggested that earlier studies weren’t very rigorous. Those criticisms were quickly picked up by creationists and intelligent design advocates, who used those doubts as evidence that natural selection itself was an incorrect explanation of the observed evolution.

With results showing that darker moths face, on average, approximately 10 percent more predation by birds than lighter moths, the new paper — the culmination of an exhaustive, six-year experiment conducted by the late Michael Majerus, a professor of genetics at the University of Cambridge — should ultimately settle those doubts, Mallet said.

“[The higher predation rate] shows a biased predation pressure against the melanic [darker] variety,” Mallet said. “The birds simply didn’t see the other moths as often because they blend in extremely well. That means natural selection is favoring the lighter-colored moths. When the trees were covered in soot, the light-colored moths were selected against. Now, on lighter trees, it’s the dark moths that are selected against.”

As one of the first researchers to raise questions about earlier peppered moth studies, Majerus had meticulously designed and conducted the years-long experiment, but died before he was able to publish his findings.

The massive study began with annual measurements of the moth population in a wooded area near Cambridge University. Based on those results, Majerus then released light and dark moths in a ratio that exactly matched that found in nature, Mallet said.

Beginning several hours before dawn, moths were randomly released in a series of spots — such as on tree trunks, where large branches met the trunk, or on limbs — where they typically rest during the day. Once the insects settled into position, Majerus spent two hours observing the area and recording whether the moths stayed in place or disappeared, having been eaten by birds. Based on those observations, he was able to conclude that the darker moths face a greater rate of predation against today’s clean bark.

“We felt this research was incredibly important so we analyzed the data he had gathered, and wrote it up for publication,” Mallet said. “This was one of the largest experiments ever conducted on natural selection. It convincingly shows that the peppered moth is one of the best-understood examples of how natural selection can cause rapid evolution.”

Explore further: A clear, molecular view of how human color vision evolved

More information: The paper was published Feb. 8 in the Royal Society’s Biology Letters journal.

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julianpenrod
1.4 / 5 (37) Feb 28, 2012
Again, among other things, notice the illegitimate tactic of declaring the evolutionary question "answered" in the article title, but then saying only the new study "should" settle all doubts.
And consider, a mere 10 percent advantage is not enough to force spot favoring of a particular trait. If birds are only 10 percent more likely to see coal black moths on peppered tree trunks, it has to be asked how much of a threat the birds represent! To say nothing of the fact that, releasing the moths hours before dawn actually allows that numbers of one type of moth might be motivated to leave while the other stays.
And, consider, this is not evolution. The essence of evolution is speciation and that did not occur here, only a supposed favoring of one phenotype over others in the same species.
Deathclock
3.7 / 5 (35) Feb 28, 2012
Again, among other things, notice the illegitimate tactic of declaring the evolutionary question "answered" in the article title, but then saying only the new study "should" settle all doubts.


What's your point?

And consider, a mere 10 percent advantage is not enough to force spot favoring of a particular trait.


No, you're an idiot.

A 0.0001% advantage (or less) is sufficient to cause selection to eventually ensure that that trait permeates the gene pool. The strength of the advantage only influences how long this takes...

And, consider, this is not evolution.


Yes, it is. Biological evolution is a change in organisms over time.

The essence of evolution is speciation


A component of evolution is speciation. The definition of "species" only has meaning to us humans. This definition has changed many times. Nature has no understanding of "species", every single organism is unique... evolution causes a change in organisms over time.
TheGhostofOtto1923
3.9 / 5 (30) Feb 28, 2012
Again, among other things, notice the illegitimate tactic of declaring the evolutionary question "answered" in the article title, but then saying only the new study "should" settle all doubts.
Not unlike your typical 'god did it' end run? Damn the evidence full speed ahead? Next stop heaven?
it has to be asked how much of a threat the birds represent!
Asked by whom? Experts who know how to properly ask these questions or delusionists who think they already know the answer?
The essence of evolution is speciation and that did not occur here
-Says the expert in ?? Wishful thinking?
Deathclock
3.3 / 5 (21) Feb 28, 2012
You don't know anything about evolution, though you have pretended like you do many times. Stop commenting about it.
TheGhostofOtto1923
3.1 / 5 (15) Feb 28, 2012
Lets see I know that
No, you're an idiot.
-Is not a useful comment. And
Yes, it is. Biological evolution is a change in organisms over time.
-I know that not all 'change' is evolution. And I know youre a compulsive flooder-type poster who doesnt know when to shut up. These things are all obvious to me.
Deathclock
3.5 / 5 (19) Feb 28, 2012
Lets see I know that..


I was talking to julianpenrod... I didn't see your comment when I posted that.

Why would give my first post a 1? I know you agree with the content, because I know you are knowledgeable about evolution.

Don't rate people based on how much you like them for christ sake, the rating system is not meant to be a popularity contest. Rate the content of the post.
Sonhouse
4.5 / 5 (15) Feb 28, 2012
It doesn't matter how much evidence is accumulated for evolution, creationists have only one response, Nay Nay. Since they cannot advance beyond pointing to the bible or quran they clearly cannot come to terms with their cognitive dissonance.
Kinedryl
1 / 5 (21) Feb 28, 2012
IMO the duality of creationism and evolution can be modelled with duality of cosmological models based on accretion and condensation, as explained here. The standard model of cosmology is assuming, the simpler lightweight particles were formed first, later their condensation the more complex objects emerged, until they formed the black holes. Actually, the evolution of large galaxies could occur in quite opposite way from sparse clouds of dark matter, which formed the dense black holes first and just after then the lightweight objects were formed. The evolution of terrestrial genes could proceed in the analogous way with less or more sudden hybridization of widespread primordial organisms, which served like reservoir of variability: it's rather merging of symbionts, rather than gradual speciation via mutations. For example the mitochondria or chloroplasts appear rather like residue of symbions already evolved.
julianpenrod
1.4 / 5 (26) Feb 28, 2012
In fact, Deathclock is wrong. It is not true that "The definition of 'species' only has meaning to us humans", that "Nature has no understandijng of 'species'".
Species are defined, unequivocally so, by the fact that they cannot interbreed! That their genome sequences are so different, one from the other, that they cannot combine in mating and produce a viable equally breeding offspring.
And, frankly, except as the absolute source of all, I never directly invoked God in considerations of everything that happened. And, frankly, if you don't know how much of a threat birds provided, you can't judge whether changes were caused by improved ability to avoid them. Walruses do not provide a great threat yto the moths, so it would be considered unreasonable to say change was an adaptation to walruses.
Kinedryl
1.4 / 5 (18) Feb 28, 2012
It doesn't matter how much evidence is accumulated for evolution, creationists have only one response, Nay Nay. Since they cannot advance beyond pointing to the bible or quran they clearly cannot come to terms with their cognitive dissonance.

IMO creationists are playing the unappreciative, but very important role of critical opposition required by scientific method based on falsification, because the mainstream biology lacks the critical feedback, and it's too sure by itself. What if the most important evolutionary steps occurred via panspermia events (F.Hoyle) or even as an attempts for terraformation of Earth by extraterrestrial intelligence? If we would adhere to the evolutionary model too blindly, we can overlook many indicia of these events easily.
TheGhostofOtto1923
2.7 / 5 (12) Feb 28, 2012
Why would give my first post a 1? I know you agree with the content, because I know you are knowledgeable about evolution.
I told you.
No, you're an idiot.
-Pointless verbiage.
Yes, it is. Biological evolution is a change in organisms over time.
-Inaccuracy.

Also past performance as a threadhog.
Deathclock
2.3 / 5 (16) Feb 28, 2012
In fact, Deathclock is wrong. It is not true that "The definition of 'species' only has meaning to us humans", that "Nature has no understandijng of 'species'".


You failed to understand the point I was making, no surprise.

Species are defined, unequivocally so, by the fact that they cannot interbreed!


CURRENTLY that is the definition. Do you have any idea how many definitions there have been?

The point I was making, that flew over your head, is that systems of classification are man made and that nature doesn't give a shit what we consider to be a species or a family or a genus... in nature, in reality, EVERY SINGLE organism is unique. Some can breed with each other and some cannot. That is a simple natural fact. The fact that we currently classify organisms by this trait and call that a "species" is irrelevant to the natural process of evolution. The fact that some organism cannot breed with other organisms is what is relevant and real.
Deathclock
3.6 / 5 (17) Feb 28, 2012
And, frankly, if you don't know how much of a threat birds provided, you can't judge whether changes were caused by improved ability to avoid them. Walruses do not provide a great threat to the moths, so it would be considered unreasonable to say change was an adaptation to walruses.


BIRDS EAT MOTHS!

You're so ridiculous.
Deathclock
2.8 / 5 (17) Feb 28, 2012
Yes, it is. Biological evolution is a change in organisms over time.
-Inaccuracy.


Change in genotype over time... I try to speak at the level of the audience. These guys don't know what genotype (or phenotype) means...

Give me a fucking break Otto...
Rohitasch
5 / 5 (4) Feb 28, 2012
What if the most important evolutionary steps occurred via panspermia events (F.Hoyle) or even as an attempts for terraformation of Earth by extraterrestrial intelligence? If we would adhere to the evolutionary model too blindly, we can overlook many indicia of these events easily.

If that were the case, it would show up sooner or later in some field of research. In any case, that won't change the fact that only luckiest or the most adapted species generally tend to survive, and within any species, the most adapted (or luckiest) individuals tend to survive and leave most offspring.
knowalot
1.2 / 5 (23) Feb 28, 2012
It is quite telling that evolution still regurgitates such conclusive proof as those lovely 19th century moths to show that humans may have evolved from a single cell over billions of years. One would expect some stronger evidence for such an exceptional and all important claim by now.

Let me quickly add that of course evolution is fact by now for modern 21st century science...
cyberCMDR
4.6 / 5 (11) Feb 28, 2012
I don't know why the creationists think proving speciation is a showstopper for the theory of evolution. Species change over time as selection pushes the frequency of advantageous or disadvantageous genes in the population. If populations of the same species are in different environments, different selection pressures and mutations will affect the two populations, so both will change over time. THERE IS NO GENETIC TRAFFIC COP that says a population can't change anymore because they became too different from the original species. Given thousands of generations, some changes will make the changed species unable (or unwilling) to mate with the other separated population. This can be caused by sexual selection criteria (pheromones, coloration, fitness preferences, etc.) or because the species can no longer produce fertile offspring. Given time, natural selection, mutations & distance, of course species are going to diverge.

Unless of course some supernatural being stops it, right?
Lurker2358
1.9 / 5 (18) Feb 28, 2012

A 0.0001% advantage (or less) is sufficient to cause selection to eventually ensure that that trait permeates the gene pool. The strength of the advantage only influences how long this takes.


Seriously? A trait needs to provide an advantage of at least a significant portion of a standard deviation to really be statistically significant compared to randomness in the environment, or randomness of encounters in the wild.

Yes, it is. Biological evolution is a change in organisms over time.


In the Darwinian sense it requires new and unique genetic traits, which did not previously exist, which produce useful systems, or improvements on existing systems in the organism.

Nature has no understanding of "species",

Sure it does. Most animals know to breed with their own kind, and aside from accidents, like in plant pollen, cross-species breeding is nearly impossible in nature.

somebody will cite ring species, but that's beside the point. the animals know compatibility.
Kinedryl
1.3 / 5 (12) Feb 28, 2012
The question is, if the number of species always increased. The creationism essentially considers, it always decreases, as the species only die out gradually. The neodarwinism considers instead, the number of species always increases, as the species evolve from simpler into more complex ones. Both these dual approaches are apparently wrong. Many species may be formed not only with speciation of existing ones, but with hybridization and merging of genes via horizontal gene transfer. It's not evolutionary or extinction event from strictly evolutionary perspective - it's creationistic event based on symbiosis of formerly parasitic species. I.e. an event based on combination of genetic material, which existed already.

BTW just bellow my post I can see the article: Gene found to have jumped from gut bacteria to beetle...
Lurker2358
1.6 / 5 (14) Feb 28, 2012
I try to speak at the level of the audience. These guys don't know what genotype (or phenotype) means...


I do.

Ironically, a Phenotype is a "mode" in which an organism exists in a different environment, evidencing quite different physical traits and behaviors, in spite of having virtually identical DNA.

Phenotype in plants is probably tied to the redundancy of the DNA, which may allow a plant to "save" beneficial traits for alternate environmental conditions for future generations when such conditions become available again, although this is conjecture on my part.

This is sort of like how plants also have the multiple types of photosynthesis.

Having both genetic, metabolic, and physiological redundancies evidencing modalism is a strong indicator of having been designed, much like a machine or a piece of software, selecting the code based on the intricacies of the unique problem at hand.
Deathclock
3 / 5 (24) Feb 28, 2012
This site is downright under attack by anti-science retards and creationists and it is disgusting.
Deathclock
2.5 / 5 (15) Feb 28, 2012
Seriously? A trait needs to provide an advantage of at least a significant portion of a standard deviation to really be statistically significant compared to randomness in the environment, or randomness of encounters in the wild.


No... a benign trait will eventually permeate the gene pool simply due to random mating. If a benign trait will then a beneficial trait of course also will, the strength of the benefit only determines the quickness with which this occurs (selection pressure).

Nature has no understanding of "species",

Sure it does. Most animals know to breed with their own kind, and aside from accidents, like in plant pollen, cross-species breeding is nearly impossible in nature.


You don't understand what I am saying. Human classification is IRRELEVANT. In reality, some organisms can interbreed and some cannot. The fact that we use this to distinguish species CURRENTLY (it didn't use to be defined that way) is irrelevant to the process.
Vendicar_Decarian
3.2 / 5 (10) Feb 28, 2012
After reading this I no longer believe in evolution.

====
"2 million Question Evolution! tracts goal of campaign fan" - Conservapedia

http://conservape...aign_fan

====

Bloody Revolution will be required.
Deathclock
1.8 / 5 (9) Feb 28, 2012
After reading this I no longer believe in evolution.

====
"2 million Question Evolution! tracts goal of campaign fan" - Conservapedia

http://conservape...aign_fan

====

Bloody Revolution will be required.


Level of ignorance: High.
Lurker2358
1.8 / 5 (16) Feb 28, 2012
BTW just bellow my post I can see the article: http://www.physor....html...


Here's the funny thing about this example:

It involves precisely tuned DNA nano-machines, the transposons, which cause an EXISTING gene to be transfered.

Even though this is an extreme case of horizontal transfer, technically no "new" genes were created, still.

Admittedly, the beetle genome was changed, but it doesn't answer the question of where did the gene come from in the first place in the bacteria, and why would there be precisely designed genetic nano-machines associated with this gene in order to transfer it to other parts of the organisms own genome, or in this case to the beetle?

This is another example of modularity of existing code from one organism being re-used in another. Albeit an extreme example.

This is in no way an example of "goo to gadget" or "goo to organ system" so-called evolution.
Lurker2358
1 / 5 (9) Feb 28, 2012
In a certain sense, this "gene" could even be viewed as a symbiotic nano-machine, like a beneficial prion, because it contains within itself the ability to move from host to host.

Ah, but there's another question:

How did the gene "know" what part of the Beetle's genome to attach itself to in order to produce a beneficial trait?

How come it didn't become attached to the beetle's eye genes, or some other gene, producing a potentially useless effect?

It just so "happened" to make a one in a billion transfer to the ideal place on the genome to enhance the beetle's metabolism, allowing it to feed more efficiently.

Now, let's see, the probability of RANDOMLY inserting a string of text into EXACTLY the right place, while NOT randomly inserting any strings into the wrong place....while supposedly blindfolded (i.e. naturalistic evolution,) and having no reference point to work with...

julianpenrod
1.6 / 5 (12) Feb 28, 2012
Those studying biology originally had thousands of years of agrarian history to work with, including sterile cross breeds. Nothing says certain animals can't or won't try to breed with others and even produce a living creature, such as mules or ligers. The concept of species deals with the similarities the animals share that allow them to produce a viable offspring. If two animals are from the same species they produce an offspring that can breed the same.
And, with respect to Lurker's comment, a phenotype is the physical expression of the genome, not the "mode" of a genome due to the environment.
Lurker2358
2.1 / 5 (7) Feb 28, 2012
And, with respect to Lurker's comment, a phenotype is the physical expression of the genome, not the "mode" of a genome due to the environment.


Yes, but you need to update your knowledge.

I pointed out the fact that what I was saying was conjecture about the redundant DNA expressing different genes, but there was a study done which strongly suggested that just recently.

Your classic example is a cave environment plant vs a plains or mountain side environment plant of the same species, having virtually identical genomes, but drastically different physical characteristics, such as a tree having much fewer limbs and foliage, thinner trunk, etc.

At first glance, you might think a cave tree should make more leaves to maximize incident radiation, but even though that would provide more energy, it would be a waste of "physical" resources in the form of nutrients and structural components.

Anyway, cave tree is classic phenotype example.
TheGhostofOtto1923
2.6 / 5 (10) Feb 28, 2012
Yes, it is. Biological evolution is a change in organisms over time.
-Inaccuracy.


Change in genotype over time... I try to speak at the level of the audience. These guys don't know what genotype (or phenotype) means...
They do know what adaptation and mutation mean, and so do you. AND youre the guy who thinks its so important to use words correctly.
Give me a fucking break Otto...
Sorry no way.
This site is downright under attack by anti-science retards and creationists and it is disgusting.
Retards...
TheGhostofOtto1923
2.3 / 5 (9) Feb 28, 2012
having virtually identical genomes, but drastically different physical characteristics
Correct. Their potential for adaption is encoded in their genes. Theyre not the first organisms in the lineage to have the need to accomodate environmental variation. White fur or saber teeth for instance can emerge and reemerge whenever they are needed.
Deathclock
2.3 / 5 (9) Feb 28, 2012
I try to speak at the level of the audience. These guys don't know what genotype (or phenotype) means...


I do.

Ironically, a Phenotype is a "mode" in which an organism exists in a different environment, evidencing quite different physical traits and behaviors, in spite of having virtually identical DNA


No.

An organisms phenotype is the outward expression of the genotype... basically any physical or behavioral trait that is evident through observation or study.

This has nothing to do with how similar the genotype is between two organisms with different phenotypes... nothing at all to do with what you said.
Lurker2358
2.3 / 5 (6) Feb 28, 2012
No.

An organisms phenotype is the outward expression of the genotype... basically any physical or behavioral trait that is evident through observation or study.

This has nothing to do with how similar the genotype is between two organisms with different phenotypes... nothing at all to do with what you said.


Weren't we just discussing organisms that have more than one phenotype?

Your brain seems to have skipped out or something.

You say one thing, and then draw an opposite conclusion.

The cave tree example is an example of a single organism having multiple phenotypes, presumably as genes vary their expression in response to the environment.

Cave tree vs forest tree.

Cave tree vs forest tree. Same species. Same DNA, different phenotype.

However, plants maintain multiple versions of each gene, and in some cases multiple versions of their entire genome, so it's obfuscated.
Shootist
3.2 / 5 (9) Feb 28, 2012
Species are defined, unequivocally so, by the fact that they cannot interbreed!


American Bison and Cows
Arabian Camel and South American Llama

Different species. Yet can produce young, which, unlike the;

Horse and Donkey

are fertile animals, not Mules.
Argiod
2 / 5 (4) Feb 28, 2012
I'd love to see natural selection explain our current crop of Republican candidates. Just how did such a pack of self-serving idiots get to the top of our food chain?
MediocreSmoke
5 / 5 (3) Feb 28, 2012
IMO the duality of creationism and evolution can be modelled with duality of cosmological models based on accretion and condensation ...... For example the mitochondria or chloroplasts appear rather like residue of symbions already evolved.


I really hope English isn't your first language.

When did Physorg become full of people assuming they have all the answers instead of people looking for better questions to ask?
kaasinees
2.5 / 5 (8) Feb 29, 2012
I'd love to see natural selection explain our current crop of Republican candidates. Just how did such a pack of self-serving idiots get to the top of our food chain?

You answered your own question.
CardacianNeverid
4.3 / 5 (6) Feb 29, 2012
I'd love to see natural selection explain our current crop of Republican candidates. Just how did such a pack of self-serving idiots get to the top of our food chain? -Argiod

That's easy. If your party values unregulated capitalism, a fundamentalist theocratic outlook, trickle-UP economics, anti-social lone-wolf isolationist policies and profit before the common good, then individuals with those characteristics will be selected for Republican representation.

I can honestly say that the 'modern' Republican party is clinically insane. It wasn't always like this...
antonima
4 / 5 (1) Feb 29, 2012

No... a benign trait will eventually permeate the gene pool simply due to random mating. If a benign trait will then a beneficial trait of course also will, the strength of the benefit only determines the quickness with which this occurs (selection pressure).


Not necessarily. If a trait is only a little bit advantageous it is quite likely it will be buried by random genetic drift, especially if the population is small. There have been some serious scholarly discussions as to whether or not genetic drift is a stronger agent of evolution than natural selection. Organisms MOST DEFINITELY evolve, but sometimes not for the reasons we may suspect.

This is just 2 years of biology coursework talking
Deathclock
1.6 / 5 (7) Feb 29, 2012
Not necessarily. If a trait is only a little bit advantageous it is quite likely it will be buried by random genetic drift, especially if the population is small. There have been some serious scholarly discussions as to whether or not genetic drift is a stronger agent of evolution than natural selection. Organisms MOST DEFINITELY evolve, but sometimes not for the reasons we may suspect.


Of course, and as you said the probability of that happening has to do with both the benefit afforded by that gene variant (allele) and the size of the population. In real world populations it is unlikely that variation will be lost due to drift... In fact, continued loss of genetic variation due to drift is one sign of population in danger of extinction due to lack of sufficient variability to adapt to an environmental change.

It's important to understand that loss of an allele through genetic drift is a wholesale decrease in genetic variation, which is almost always bad for the population.
Deathclock
1 / 5 (3) Feb 29, 2012
Also, I'd like to see where anyone of any reputability has suggested that random drift contributes more to evolution than natural selection... sounds like the words of a closet creationist trying to discredit evolutionary theory with the old chestnut "randomness doesn't increase complexity. A tornado in a junk yard will not create a working automobile..."
Deathclock
1.6 / 5 (7) Feb 29, 2012
I ran out of room in the above, but I wanted to add that Hardy-Weinberg equilibrium, though suspected to be impossible in nature, precludes the loss of genetic variation due to drift...
Deathclock
1.6 / 5 (7) Feb 29, 2012
In fact, in a population of only 200 there is only 1 in 1.6×10^60 chance of eliminating an allele in any given generation if there is no selection pressure on that allele. That is less likely than picking a particular atom out of every atom in the sun.
antonima
5 / 5 (1) Feb 29, 2012

Of course, and as you said the probability of that happening has to do with both the benefit afforded by that gene variant (allele) and the size of the population. In real world populations it is unlikely that variation will be lost due to drift...


I see what you mean. But in the case of NEW mutations, which realistically exist in only 1 member of the population, it is not unimaginable that it will be lost due to random luck. If we have a constant population, and a mutation arises which increases fitness in an individual by lets say .05 (which is very very high), then in that population there will only be 1.05 individuals which receives the mutation, per generation (assuming a constant population size). This individual in a natural scenario has a high probability of being eaten, dying of disease, confronting unfavorable climates, etc. So, even a highly advantageous mutation can disappear very quickly.

antonima
5 / 5 (2) Feb 29, 2012
I ran out of room in the above, but I wanted to add that Hardy-Weinberg equilibrium, though suspected to be impossible in nature, precludes the loss of genetic variation due to drift...


The point of my comment was to show that these things aren't always as simple as it appears at first.

What you said, that fixed alleles aren't likely to disappear, is 100% true, unless there is a selection pressure acting on the population carrying these alleles. An interesting example of this is the decrease in size of fish in the Atlantic. Smaller fish are less likely to be caught in a net, and palatable fish are reacting to the evolutionary pressure that fishing nets present. These fish are getting smaller, not because they don't grow to be adults, but because the alleles responsible for large size are selected against.
julianpenrod
1 / 5 (5) Feb 29, 2012
In point of fact, the key is still "breeding true", that is, reliably producing progeny morphologically the same as the parent. Usually, this encompasses progeny not occurring or being sterile. But, consider, if two offspring of camel and lama mating mate, the likelihood is significant their offspring will be mostly camel or mostly llama and, after a few more generations, the variations can be "bred out". A chimp mates with another chimp, then their progeny mates with another chimp and so on and the result is still a chimp. When "munchkin" cats first appeared, they were carefully interbred to "fix" the mutation. But they interbreed both with other munchkins and cats of normal leg length.
Deathclock
1 / 5 (3) Feb 29, 2012
I see what you mean. But in the case of NEW mutations, which realistically exist in only 1 member of the population, it is not unimaginable that it will be lost due to random luck. If we have a constant population, and a mutation arises which increases fitness in an individual by lets say .05 (which is very very high), then in that population there will only be 1.05 individuals which receives the mutation, per generation (assuming a constant population size). This individual in a natural scenario has a high probability of being eaten, dying of disease, confronting unfavorable climates, etc. So, even a highly advantageous mutation can disappear very quickly.


Yes this is true, but it's also true that most mutations occur over and over again... it's not as if there is only one chance for it to ever successfully "stick". You can see this most easily in detrimental mutations that effect humans, such as sickle cell anemia, downs syndrome, and many others.
Deathclock
1 / 5 (3) Feb 29, 2012
The point of my comment was to show that these things aren't always as simple as it appears at first.


Sure, but jumping right into the complexities given the typical audience here is unwise, I try to keep my posts simple so that these whackjobs that clearly don't know anything about evolutionary theory can understand me.

An interesting example of this is the decrease in size of fish in the Atlantic. Smaller fish are less likely to be caught in a net, and palatable fish are reacting to the evolutionary pressure that fishing nets present. These fish are getting smaller, not because they don't grow to be adults, but because the alleles responsible for large size are selected against.


I'd warn against considering this a selection "against" large body size and instead consider it a selection for smaller body size... just a nit-picky kind of thing, but it's more useful and accurate to view natural selection as a selection for something, rather than against the opposite.
9999
1 / 5 (4) Feb 29, 2012
It is interesting how folks who eagerly push their agenda frequently overlook the obvious! Let's just take a look at the second paragraph of the article.

Note there, that author Peter Reuell either does not understand evolution OR he just isn't that sharp.

He points out how the "increasing numbers" of the melanistic phase began prevailing as the environment got dirtier. The fact is that there always were both phases. The darker ones prevailed during the sooty steam age and the lighter ones regained their earlier preeminence as the environment was cleaned up.

The fittest always survive the best. However, NO NEW GENETIC INFORMATION is indicated here. That is only imagined by folks who are defending the indefensible.

VERY POOR TRY ! ! !
flippertie _
not rated yet Feb 29, 2012
deathclock :In fact, in a population of only 200 there is only 1 in 1.6×10^60 chance of eliminating an allele in any given generation if there is no selection pressure on that allele. That is less likely than picking a particular atom out of every atom in the sun

Could you explain where that figure comes from?
Deathclock
1 / 5 (3) Mar 01, 2012
@flippertie:

Honestly, wikipedia... lol.

Go to wikipedia's page on genetic drift, they explain it using an example involving paint cans or something... that figure is stated somewhere towards the end of that explanation and then the math required to derive it yourself is provided as well.

It's basic statistics though. If you have 200 chances to either get one variant or the other, and there is a roughly equal chance of getting either (which is a simplification, granted, but with no selection pressure it's accurate enough), then there is only a very tiny chance of getting all the same variants in all 200 chances. It would be like flipping a coin and having it land heads up 200 times in a row.
Deathclock
1 / 5 (3) Mar 01, 2012
The chance of getting heads 200 times in a row is 0.5^200... which turns out to be 6.2x10^-61.

Keep in mind, populations in the real world have thousands to billions of individuals, not 200... There is virtually no chance of eliminating an established allele through genetic drift.

Though Antonima was correct that this does not apply for a NEW mutation, but it's important to remember that the same mutations typically manifest over and over again, it's not like a beneficial mutation will only occur once and if that animal happens to die then oh well too bad... the same beneficial mutation will occur constantly with a stable frequency until the genome changes enough that it is not a likely mutation anymore. This is why things like downs syndrome or other genetic "diseases" don't only occur in one human ever and then never happen again, but instead occur constantly with a specific frequency.
Tausch
1.6 / 5 (5) Mar 03, 2012
http://www.brookl....HP.html

Ammo. An attempt at the reader level request.
The least I can do for an interesting thread - if you can filter out the mutual emotional exchanges and separate those from reasoning representing insightful discourse.
malapropism
not rated yet Mar 04, 2012
... a Phenotype is a "mode" in which an organism exists in a different environment, evidencing quite different physical traits and behaviors, in spite of having virtually identical DNA.

Um, no, not exactly. In simplified terms, a phenotype is the physical manifestation in the organism of the genotype. It is not necessarily related to, nor dependent upon, a particular environment nor environmental condition. For example, as part of some research I did, I used genes from 2 phenotypes of a single (sub-)species; 1 of the phenotypes showed gigantism, brought about by a triploid genome - there were no "environmental" differences because I controlled for them.
malapropism
5 / 5 (1) Mar 04, 2012
Phenotype in plants is probably tied to the redundancy of the DNA, which may allow a plant to "save" beneficial traits for alternate environmental conditions for future generations when such conditions become available again...

Sorry, no again. "Gene banking" like this does not occur. Mutational load increases but not for possible future benefit but simply because, as Deathclock has quite rightly noted, it doesn't require a massive benefit to accrue from a mutation in order for it to stick around or even to proliferate, or *any* benefit, it simply needs to be not detrimental. (If you don't believe me, look up "Muller's Ratchet" and associated papers.)
...Having both genetic, metabolic, and physiological redundancies evidencing modalism is a strong indicator of having been designed...

Metabolism and physiology derive from the organism's genetics so these are not 3 separate things as you are suggesting. The "redundancy" is not designed, more like a failure to remove cop
malapropism
not rated yet Mar 04, 2012
Oops, damned character count limit...

The redundancy of genes is not "designed" but is most commonly a consequence of the failure to remove copies of genes when those copies are not deleterious to the organism itself in an immediate sense (i.e. they don't kill it outright) and are not deleterious to it's ability to reproduce (and hence pass the genes on to the next generation).

If a redundancy of genes was an indicator of the genetic mechanism being designed, we could reasonably expect that only currently "useful" genes would be duplicated redundantly. After all, if there was a designer, then any time some environmental change occurred requiring a new genetic trait, he/she/it could simply introduce new genes for an appropriate trait; no "gene banking" such as you suggest would be needed. Otherwise, why not have genes for every possible eventuality but most simply "switched off"? If you say that the designer no longer intermediates, then process must now be natural selection based.
Julia___
1 / 5 (2) Mar 26, 2012
If evolution was true then how come there are no species in between one and the other. For example if humans did come from monkeys/gorillas then why is there no creatures in this in between stage, surely they couldn't have all died out when we and the monkeys/gorillas are so successful...

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