Discussion in 'Biology & Genetics' started by Hercules Rockefeller, Mar 9, 2009.
You didn't understand the point that was being made.
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The smallest unit of evolutionary change is not a single generation?
Don't mind me asking, because you went on some tangent on some random topic, which is not understandable why for my rather logical mind trained for years being an accountant.
No I explained in my answer that your POV about a generation is not important or even well defined. I have no idea what you meant by a generation. Is that some fixed number of years? As a woman can have two separate births in 20 months, perhaps you should define your "generation" as 10 months? Please tell how many years or months you are talking about is a generation for an evolutionary step.
Again, and briefly, evolution is the slow change in the reproductively active gene pool. In a population of N individuals only n (n < N) have the capacity to reproduce. An even smaller fraction will reproduce. They are the active reproductive gene pool. The life spans and deaths of the others have no influence on evolution.
Anyway I told you in prior post that your concept of an "evolution generation" was "totally wrong" as it makes no sense for discussion of evolution. It is not even definable, I think, for discussion of evolution, but I invite you to try.
Again: What is your definition of a generation? I.e. do your even have any idea about what you are talking about? I think not. I think it is all just nonsense. Thus, it is you who have gone off on "on some tangent on some random topic, which is not understandable" because even your term "generation" is without meaning for discussion of evolution.
If I am wrong, prove it by giving some definition of "generation" which has even the slightest utility in a discussion of evolution.
SUMMARY: If you cannot even define your terms, then clearly you are talking nonsense and are off on some random topic tangent no one can understand.
I appreciate the link, thank you.
I don't mean behavioral evolution rather behavior causing the adaptation.
Blacks in America which endured the slave trade endured harsh conditions. It seems as a result their offspring have certain advantages.
Bone density at all skeletal sites was statistically significantly greater in black persons than in white persons
Is this to you an example of behavior influencing genetics? If so how exactly does the DNA change. What is the transmitter here that I'm missing? How does a behavior translate to the genetic level?
We've estimated 25,000 human genes. Are there any genes we've fouond that are confirmed to be behavorial?
You see the Hippo is the perfect example. Eye's front in a predator style. It also comes up for air and spends a certain amount of time above water. It pursues it's prey like a croc, or gator from above water using stealth. To me this is where it may break down. It seems echolation would take a very long time to development.
Echolation seems like a long range sensor or even a probe. Imagine to begin to detect the differences in sound isn't just a ear issue it's a brain issue. You said navigation before. Cold water causes a change in sound especially over extreme distance. I could see the first echolocation being used to guage distances in the ocean but not to see. Of course the closer you get to something the faster the return. It allows you to know what the sound is aswell. To get good at this is a brain function. To become specialized to this is a physical function, the Melon, the phonic lips then of course the "array" that allows the dolphin to gather the sound from almost every direction.
It seems a bit much to ask of an un isolated species but then the ocean is it's own type of isolation. Whales and other sea life use echolocation but it's not as wide spread as I thought. Is there a copious amount of biosonar users?
I'll have to look into it.
The DNA is already changed. Within any given generation of organisms, you'll find a wide degree of variation. Just look at your family- even though you are all closely related, you are all quite different! So some blacks would have had higher bone densities to begin with, and your "behavioral" example would select for those with higher density, so the average density would go up over time.
Other behaviors that could be selected for would be, for instance, mimicry behaviors. There are many insects and spiders that pretend to be ants, because most birds (a major predator of arthropods) don't like to eat ants. These spiders move like ants- their movement could be described as "antlike behavior". They're very convincing. Unless you get down on your hands and knees, you'd think they were ants! You have to count their legs to realize that they're not in Hexapoda. The evolutionary explanation for how these spiders became such good mimics would be that ancestors that were the best mimics of ants produced the most offspring. And in each subsequent generation, only the best mimics got to pass on genes.
No. Many have been implicated, but most of the time it's the popular press taking things out of context or a scientist looking for publicity. Many geneticists are hesitant to publish such work, since it will often kick off controversy.
I know of a microsatellite (or STR in the new jargon) locus that has been associated with novelty seeking behavior. People with tri-nucleotide expansions at the loci score higher on a "novelty seeking" test. I can't think of any off the top of my head, but their are a bunch of correlational studies linking certain behaviors with loci. I'm skeptical of these studies, since the social impact of such findings could be quite severe, while the science isn't that great. There are a lot of reasons why a group of humans may have the same locus and exhibit the same behavior, but without any relation between the two.
The FOXP2 gene has been implicated in speech in humans. Speech pathologies arise when their are mutations in the genes.
Here's the wiki page on it:
It's even been implicated in the in the development of bat sonar.
Here's the wikipage on the evolution of cetaceans:
I've linked the bit of artist's reconstructions of animals based on fossils they've found, and as you can see, it goes from a sort of deer like creature to something like an otter.
It took about 15 million years for dolphins to go from totally terrestrial to totally marine, which, if you assume an average generation time of 15 years (it's 20 years for humans), is one million generations.
I'm not sure why you would an isolated species. Isolation leads to the loss of traits, not the gain of traits, since isolation tends to remove selective pressures. You seem hung up on the idea that newly evolved traits are handicaps. You have to remember that even pieces of systems can be immensely beneficial, and that we also tend to have pieces of systems that we don't need that later get used. Eukaryotic genomes are quite large, which leads to a lot of variability. I refer you again to the LTEE:
"In 2008, Lenski and his collaborators reported on a particularly important adaptation that occurred in one of the twelve populations: the bacteria evolved the ability to utilize citrate as a source of energy. Normally, E. coli cannot transport citrate from outside the cell to the cell interior (where it could be incorporated into the citric acid cycle); the lack of citrate transport is considered a defining characteristic of the species. Around generation 33,127, the experimenters noticed a dramatically expanded population-size in one of the samples; they found that this population could grow on the excess citrate in the growth medium. They found that the ability to use citrate could spontaneously (although rarely) appear in cultures replicated from earlier frozen samples of that population, from before the citrate mutation appeared, but not in the other 11 populations or in samples before generation 20,000. According to the authors of the study, this suggests that the mutation depends on an earlier, perhaps non-adaptive, change—and more generally (following the argument of Stephen Jay Gould) "that historical contingency can have a profound and lasting impact" on the course of evolution."
Selective pressures in the evolutionary period of the proto-dolphin were not the same as they are now. Having incomplete or poorly functioning, but novel, systems, where no one else has one a good defense against it, is extremely beneficial.
Wikipedia has only mammals listed as echolocaters: cetaceans, bats, and shrews. This might be because manipulating all the complex information from echolocation requires a big, warm-blooded brain. Of course, their may be arthropods, molluscs, birds, or fish out there that use it, but we haven't yet observed.
A generation is the period of time it takes for an organism to reproduce from it's "birth". A human generation is usually calculated as 20 years, while E. coli is 9.8 minutes in a good growth medium.
I believe, definitionally, that a generation is the smallest unit of time evolution can act over. While bacterial competence (picking up plasmids from the environment) can, and does, confer fitness, by its survivability, it only counts as evolution in reproduces, since evolution is defined as:
"In biology, evolution is change in the genetic material of a population of organisms from one generation to the next."
A change in genetic material of a non-reproductive population is not evolution, since they won't be passing the genetic material on into another generation.
I only see discrediting the messenger and not the argument. Are you still denying that the smallest unit of evolutionary change is one generation span? Because it is just textbook knowledge. I just see people jumping on the bandwagon. They see 'friends' discrediting my statements and without thinking they do the same. My definition is exactly that of Darwin. Are you calling him wrong? That's a bit arrogant.
You are using Lamarkian concepts here. This is like supposing that the giraffe has a longer neck because it reaches to feed. One of the early evolution theories was the notion that traits were modified during the lifetime of the organisms. It was learned that this was not correct. Evolution does not occur to the individual, but to the species.
Roman there are bird species that echolocate: swiftlets and oilbirds
Tuberculatious evolution does not happen to the individual. It happens to a species.
I can see the old account coming out. If money A is transferred over time B, then there must be an audit trail showing all of the transactions so that money A can be tracked. Then you say that if 1 penny was sent each time, then there isn't enough time in B to transfer all the money so some other way must be at hand. Or something like that.
Are you planning an 'ah ha' attack in which you state your question in a nebulous manner so that some unwary person gives you an answer that you can unjustifiably pounce on and yell ah-ha?
Since we realize what you are doing with "smallest unit of evolutionary change" why don't you toss out your idea in a clear manner. Accountants can do that well.
I am becomeing convenced you are a troll as twice now I have told your that the smallest unit of evolurionary chage is not a generation and explainded that you are just posting nonsense as you can not even define what is a "generation" for that term to have any sensible application in a discussion of evloution.
I have asked you at least four times to try to define it or at least tell how many years of months you think is a generation for an evolutionary step. You have not, so as I suspected, you can not. Thus, I conclude you are just a troll who just continues to post your nonsense.
After three stikes you are out, so I will not reply more to your trolling on this, until you at leas try to define waht you mean by "generation" that has even the slightest sense as an evloutionary step.
In case you do not even know the form of a definition, I will help you get started:
A generation for use in discussion of evolution is _________ .
I may be wrong, but do not think this is quite correct, although it has come to mean behavior modifies genes in the Western world. I believe the Lamarckian POV was not so much that behavior modifies the genes or inheritance, but that genes were unimportant -All that was required was the correct environment.
I am not sure how much he actually believed this, as he was under extreme ideological pressure to support this POV. The Soviet Union was according to the CP constructing the new soviet man, who would not suffer from the selfish drives of greed, but work for the good of all (meaning the CP directed state.) As the CP could not replace the genes of the Russian population, this POV was the only one consistent with the construction of the "new soviet man."
When "only the environment matters" not genes, was applied to agriculture that meant good tilling of the soil, proper watering, fertilizer, and insect control. No need to have good seeds.
The USSR nearly starved with this approach but fortunately small plots, often just back yards where the peasants knew better, were productive and Moscow did not starve, but just had food rationing and an active black market in food.
Billy T I am not referring to Lysenkoism.
I am referring to Lamarck, a one time student of Buffon back in the 1700s in France.
Thanks. You are absolutely correct. I work from memory and had merged these two very different POVs into one. Again thanks for correcting me.
Look up epigenetics some time. Chromatin remodeling occurs over the course of a lifetime due to environmental factors, and these changes in chromatin- the way genes are stored- is heritable. One of the best examples was discovered in obesity research, where fat mice had fat daughters, despite having identical genomes as the control group.
Technically not evolution, as there is no change in allele frequencies, but quite Lamarkian. B cell replication in mammals during an immune response undergo what's called hypervariable somatic mutation, where B cells use error prone DNApol to increase the mutation rate in the Ag-binding domains of their immunoglobulin. B cells with mutated Ig that binds Ag poorly are given cell-death signals, while B cells with mutated Ig that binds Ag well are given cell survival signals. At the end of the immune response, you have a population of B cells that produce Ab that are superior at binding that Ag than in the beginning. As far as I know, these B cells aren't heritable, so this isn't even an example of Lamarkian, but interesting nonetheless.
Did he claim it happened to the individual?
He phrased what he meant poorly. A generation (a well defined biological concept; please look up what it means) is indeed the smallest period of time over which evolution can take place. It would also help if you knew the definition of evolution. If you give it just a little thought, you'll see that there is no smaller unit of time over which evolution can occur.
One Generation is just the transition from parents to offspring. Individuals. Not from a whole population. So many generations are happening within a population at the same time. It is not connected to the question whether evolution happens on the level of the individual or population. Evolution isn't static after all, so it happens to a historic series of connected individuals.
Natural Selection. The strongest surviving increasing the number of the strong. FASCINATING how that worked in just some 400 years!
So they observe and study other creatures for their own survival.
But how does the behavior get passed on?
ah...no that's not what I'm thinking.
I'm looking for "velocity" ...in a way.
I'm sorry it seems like this was saying that certain bacteria couldn't change to the new source. Why?
Then if you could describe whether this is an adapation or a mutation.
I see mutation yet i'm thinking this was an adaptation.
Now that's fascinating.
Thanks for the time.
Have you heard of drift? It's basically evolution driven by no selection at all! If you start with a small population, just random chance can lead to fixation of alleles. Wikipedia has a cool example of it with marbles and jars:
Also, note that blacks coming from Africa were under a lot of selection- many died on the voyage over, for instance. Also consider that they came from environment where dense bones were probably already selected for, while Europeans weren't as much. For the next 400 years, Europeans were under less selection, while blacks were under constant selection. It may simply be an artifact.
No; mutations in their nerve structure (hard to say a spider has a "brain" like we think of brains) and interpretation of external clues leads them to behave more and more like an ant. There's no need to invoke higher thought processes at all.
Ah. Yes, sexual selection can lead to bizarre, "runaway" traits.
Actually, they started with a dozen or so original colonies. In one line, and only one, the bacteria developed the ability to use citrate.
Every 75 days they would freeze a petri dish or what have you of bacteria from each culture, for the past 20 years. So they would take the petri dish out that was from 75 days before the cit+ mutation, let it grow, and that too would develop into cit+ bacteria.
However, if they went too far back, or too far from that cell line, they couldn't get the cit+ mutation. This suggests that the bacteria had, at some point, a set of mutations that set them up for one more single, critical mutation to push them over into being able to metabolize the substrate.
Does that make sense? The steps prior to the critical mutation are important, too, seeing as how if you went too far back in time, you couldn't get the Cit+ mutation, since all the mutations leading up to hadn't occurred.
Also note that these mutations all occurred at the same time as all the bacteria were increasing fitness! In fact, fitness plateaued in their glucose environments after so many thousands of generations. This supports the idea of slow, incremental change. Then wham! you get something like the ability to metabolize citrate, in an almost overnight change, which supports the idea of punctuated equilibrium. Note, too, that the bacteria had to have an environment to "move into". The Cit+ mutation would have been a mutational footnote if they were in, say, a Lac+ environment.
It was a series of non-adaptive mutations (as far as they could tell) that ended up being an incredibly adaptive mutation.
If you recall, I said the evolutionary time for dolphins to go from deer-ancestor to fully marine was 15 million years. This is a bit misleading, as the dolphins have something like 100 million years of evolutionary history as mammals, which means, among other things, that there could be mutations that occurred in the past that didn't have much effect, until the dolphin-ancestors decided to go swimming. Much like those bacteria.
You really do not get it.
Only the most intelligent creatures (all in the ape family, I think) learn by watching others*** or educate their off springs (to pass acquired behaviors on to the next generation, such as how to process a twig by chewing on end of it etc. so that more delicious termites will stick to it when it is inserted and then width drawn from a termite nest.)
Evolution is a sequence of RANDOM genetic changes* with no planning, no purpose and no goal. These chance changes occur for various reasons. Only via man's selection** has there been any purposeful or planned evolution via the "selection," I think. Following each of the changes there is some positive, neutral or adverse impact on the change of the individual with the genetic change to reproduce.
For example, a random change which made a cow produce more milk might be noted by cow's owners 5,000 years ago and that cow, instead of another, got put into the field with the bull. I.e. the random genetic change caused by a “more-milk-production” gene caused a greater chance for that cow to reproduction, due to man’s choices and values. This repeatedly done for centuries has produced cows with grossly enlarged utters.
*No longer strictly true as man is beginning to understand some of the information coded in the gene of various animals and plants. With this knowledge and "genetic engineering" man is now purposefully modifying some organisms by introduction of non-random genetic changes.
Where it will all lead no one knows. Perhaps, in the long run, only random changes and natural selection would make for a more stable and diverse mix in the bio-sphere. I am quite concerned by the monoculture of grains etc. Millet was only a few thousand years ago more grown than wheat, I think, for food but, I think, is more labor intensive to use (less profitable).
**Man has been guiding the selection of some creatures for something on the order of 50,000 years, I would guess. For example, man converted wolves into dogs by killing the more hostile wolfs and feeding (or at least allowing) the more timid ones to eat some of his scraps, etc.
*** The SPCA would skin you alive if you tried to repeat an old experiment on dog's ability to learn by watching others. About 24 pound dogs were not feed one day, and staked by short leash uniformly around in a circle of about 30 feet diameter. The man who normally feed them was at center of circle with a club. He walked directly to one, which wagged its tail as he approached, presumably it was hopping to be feed, but he clubbed it to death in full view of the other 23 and then returned to the center of the circle before walking to the second dog to club it to death. Etc. Even dog 24 was wagging its tail as the man approached. Perhaps only 18 dogs? - It was long ago I read this report.
Felines will teach their offspring the proper way to kill and open up prey. Dogs can watch owners and learn where things are located. Some cats and dogs have even figured out how to open doors. Many, many types of birds are able to watch and learn from their fellows.
Even octopus in a tank next to a tank with another octopus in it can learn which colored items have food in them and which do not, simply through observation alone.
Separate names with a comma.