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originally posted by: PhotonEffect
Yes genes are very important in all if this, but epigenetics is showing that variation can occur without changes to the underlying nucleotide sequence. Hence no mutations required. And with new technologies to study the genome, researchers are finding evidence of epigenetic signatures more and more.
originally posted by: PhotonEffect
I'm asking specifically how a researcher, looking at an organism or a group of organisms, can determine whether those phenotypes came about due to natural selection or genetic drift?
originally posted by: PhotonEffect
My take way is that it's not at all an easy process, which I suspected. Yet much of how we verify certain evolutionary mechanisms in a population is based on it's size. Genetic drift, it's said, can't be measured in large populations. But since we can't easily determine what is sufficiently large (or not), it seems it must involve quite a bit of guesswork.
originally posted by: PhotonEffect
Taking your volcano example – if you were to observe those organisms which survived, how do you determine if it was due to some beneficial trait that allowed them to escape the inferno (natural selection), or that perhaps they just happened to be in the right place at the wrong time (genetic drift)?
originally posted by: PhotonEffect
Would a selectionist see it differently?
originally posted by: PhotonEffect
Are you saying that traits are only the effect of mutation? If so, I will respectfully have to disagree.
originally posted by: PhotonEffect
Thanks, yes, I've read this one. I think it does well at explaining that there is not at all a linear relationship between genotype and phenotype. So a mutation is not generally going to cause meaningful effect on its own.
originally posted by: PhotonEffect
Okay, so you do think mutations alone are responsible for trait expression.
originally posted by: Barcs
I don't think I've ever said that it's simply mutation and natural selection, and that's it. And no it's not antiquated because genetic mutation and natural selection are observed CONSTANTLY in ongoing experiments.
Washington State University researchers say environmental factors are having an underappreciated effect on the course of disease and evolution by prompting genetic mutations through epigenetics, a process by which genes are turned on and off independent of an organism’s DNA sequence.
Their assertion is a dramatic shift in how we might think of disease and evolution’s underlying biology and “changes how we think about where things come from,” said Michael Skinner, founding director of the Center for Reproductive Biology in WSU’s School of Biological Sciences.
“The ability of environmental factors to promote epigenetic inheritance that subsequently promotes genetic mutations is a significant advance in our understanding of how the environment impacts disease and evolution,” they write.
originally posted by: Barcs
It's great that you think other factors are involved, but can you please break down how many species are said to have evolved via epigenetic factors, that do not include genetic mutations?
In contrast with the standard assumption, our model predicts that adaptive resistance cannot be explained by increased mutation rates. Our results identify the molecular mechanism of epigenetic inheritance as the main target for therapeutic treatments against the emergence of adaptive resistance
originally posted by: Barcs
Little is known about epigenetics, more work needs to be done before incorporating it into MS. Epigenetics has only been observed in a select few simple species and it is about gene EXPRESSION, not the development of new traits. If I'm wrong about this, please correct me,
originally posted by: PhotonEffect
a reply to: Barcs
Are you aware that locusts and grasshoppers are actually the same species? Locusts are actually morphs of grasshoppers when the environment changes (typically due to overcrowding, then they swarm like madmen!). What's crazy is they look and act very different from each other. And guess what they suspect could be the impetus of this Jekyll and Hyde phase change? Yep. And yep.
originally posted by: Barcs
Can you explain to me how natural selection is ever not a factor, even in cases of genetic drift? I thought I questioned this in my last response.
originally posted by: Barcs
I was hoping you could provide a model of evolutionary diversity that does not include natural selection or at least explain how this would be possible. I'm only familiar with the standard model, I have not seen any others.
The neutral theory of molecular evolution holds that at the molecular level most evolutionary changes and most of the variation within and between species is not caused by natural selection but by genetic drift of mutant alleles that are neutral.
originally posted by: Barcs
I never said that it wasn't drift. You are looking at it like an either/or scenario. I think you missed my point in breaking up my post the way you did. I was trying to say that natural selection STILL plays a role in populations that experience genetic drift. How could it not?
originally posted by: Barcs
Are beneficial mutations more rare than epigenetic factors in evolution?
originally posted by: Barcs
Because genetic mutations are not just recombination of DNA. There are several different ways that genetic coding sequences can be changed.
originally posted by: Barcs
I just don't understand the big fight here against genetic mutations and NS as if they aren't responsible for the vast majority of observed evolutionary changes even when epigenetics may apply.
originally posted by: TerryDon79
What's your take on the recapitulation theory? Not just what it is, but if it's got any feasibility, in your opinion.
originally posted by: Ghost147
originally posted by: TerryDon79
What's your take on the recapitulation theory? Not just what it is, but if it's got any feasibility, in your opinion.
I'm actually not too familiar with the details of the concept. I know of it, and I know it's been thoroughly debunked, but I have also heard that some scientists still feel that parts of it could still apply to some degree.
Unfortunately I'm not familiar enough with it to really state an opinion on the matter
originally posted by: Ghost147
You may be mistaking me. I don't consider the mutation of genes to be the only cause of variation. However, it is the primary. Epigentics is a very interesting subject.
originally posted by: Ghost147
The effects can be seen through the genetic diversity of a population, that's the point I was was trying to put across. Genetic drift leads to a smaller gene pool in one way or another (Bottlenecking/Founders), and thus significantly reduced genetic variety.
originally posted by: Ghost147
We can show that a species had gone through some sort of genetic drift in the past by testing populations of the same species and then comparing their DNA. One sign of genetic drift would be a detection of a significant number of haplotypes that spread across many, if not all of the tested populations.
originally posted by: Ghost147
It can be measured in larger populations, at least if there was a time when the population had once gone through genetic drift (as mentioned above).
Nevertheless, in some areas in biology, there is a lot of guesswork. But again, no one is claiming there is none.
originally posted by: Ghost147
You're viewing it in kind of the wrong way. Genetic drift only occurs after the fact that the volcano wiped out or separated the population.
originally posted by: Ghost147
It's not necessarily a matter of "did natural selection do it or did genetic drift do it" because they are on a different spectrum in this context.