Evolutionary mechanisms

[Ronald Hyde]

Just the title of this topic sets off little alarms, and when I open I find they are valid.

 

Even Darwin knew that Evolution was 'not Darwinian'. He just observed that biology only made sense if this process, which is

exactly what Evolution is, occurred in Nature. He knew of no mechanism, nor postulated any, that would come much later. We

are still only learning of what mechanisms occur. Nature is very 'inventive'.

[darryl88]

Are you asking anything diffferent in this new thread or should we just merge

the threads so all the replies are in a single, easily found and understood

place?

 

There is a paradigm shift in evolutionary biology at the moment, many scientists are claiming the neo-Darwinian synthesis has been replaced. However this news has not broken out onto internet forums. I did start one other thread about this, but that was more concerned with the "extended synthesis". It seems the "extended synthesis" is not actually enough for some scientists. It seems new discoveries have totally replaced elements of the neo-Darwinian synthesis making that framework outdated. Would be interesting to get some comments on this paper:

 

Michael R Rose and Todd H Oakley, in their research paper, titled "The new biology: beyond the Modern Synthesis" published on 24 November 2007 wrote that The last third of the 20th Century featured an accumulation of research findings that severely challenged the assumptions of the "Modern Synthesis" which provided the foundations for most biological research during that century. The foundations of that "Modernist" biology had thus largely crumbled by the start of the 21st Century. This in turn raises the question of foundations for biology in the 21st Century".

 

http://www.biology-d...content/2/1/30/

Edited October 4, 2012 by darryl88

[swansont]

!

Moderator Note

Wow, so biology is much more complex and rich than was imagined before DNA was discovered and modern investigative techniques invented. Knock me over with a cinder block. What, exactly, do you want commentary on? What is the point you wish to discuss?

[Ronald Hyde]

Seriously, all that you need to understand about evolution is that it is a process, and to understand its mechanisms. Period, end of story.

 

Failed philosophical notions are a paradigm a dozen.

[CharonY]

The only thing of note is that we still do not have collected all the mechanisms and have not a complete integrative view of those that we do know. This is hardly surprising though, as biology is a very dynamic field where we still often find new bits and pieces (and are often not very good in integrating the bits we find).

[Ophiolite]

What we call something is, or at least should be, less important than what it is. Our understanding of evolutionary mechanisms is still far from complete and, as CharonY points out, not fully integrated. Large steps have been taken over a century and a half. Is it important to mark those steps? Important, but not necessarily essential.

 

Darwin's idea was accepted with suprising alacrity by the scientific community, supporting the claim by some that it was an idea whose time had come. (And Wallace served to offer confirmation to that notion.) Yet by the turn of the century Darwinism was all but dead as people gravitated to mutation and the concepts of Mendel rediscovered by Bateman, de Vries and Corren. When the two were fused in the 1930s and 40s did the resultant concept merit a new name? One could hardly call it Haldane/Huxley/Dhobzhanksy/Fisher/Simpson/Stebbins/Wright/Mayrism, so the Modern Synthesis was born.

 

And now, more than half a century later, we've learnt even more about the mechanisms and processes, so much more that some people think a new name is in order. Is it?

 

I said at the outset that what we call something is, or at least should be, less important than what it is. But is this true? Darwin may have been the right man in the right place at the right time, but he ignited a revolution that is arguably of greater scientific importance than any other. His handful of principles still lie at the heart of evolutionary thought, so my view is simple. Let's just call the current hypothesis and those that will develop in future, Darwinism. Direct, concise, effective.

 

And it has the secondary advantage that it will piss off the creationists.

[Ronald Hyde]

What we call something is, or at least should be, less important than what it is. Our understanding of evolutionary mechanisms is still far from complete and, as CharonY points out, not fully integrated. Large steps have been taken over a century and a half. Is it important to mark those steps? Important, but not necessarily essential.

 

Darwin's idea was accepted with suprising alacrity by the scientific community, supporting the claim by some that it was an idea whose time had come. (And Wallace served to offer confirmation to that notion.) Yet by the turn of the century Darwinism was all but dead as people gravitated to mutation and the concepts of Mendel rediscovered by Bateman, de Vries and Corren. When the two were fused in the 1930s and 40s did the resultant concept merit a new name? One could hardly call it Haldane/Huxley/Dhobzhanksy/Fisher/Simpson/Stebbins/Wright/Mayrism, so the Modern Synthesis was born.

 

And now, more than half a century later, we've learnt even more about the mechanisms and processes, so much more that some people think a new name is in order. Is it?

 

I said at the outset that what we call something is, or at least should be, less important than what it is. But is this true? Darwin may have been the right man in the right place at the right time, but he ignited a revolution that is arguably of greater scientific importance than any other. His handful of principles still lie at the heart of evolutionary thought, so my view is simple. Let's just call the current hypothesis and those that will develop in future, Darwinism. Direct, concise, effective.

 

And it has the secondary advantage that it will piss off the creationists.

 

OK, so we define Darwinism as the belief that Evolution is an ongoing process that occurs in the natural world.

And add that we only need to understand the mechanisms which underlie it, not impose any philosophical 'paradigms' upon it.

 

I can totally live with that as an answer to the original posters question or post. Anyone else agree?

[CharonY]

I would eliminate belief from that statement as it implies a meta-view on the process. Whatever we call it (either Darwinism, new synthesis, Mocklefrock) describes the evolutionary process (to the extent we understand it) and forms the theoretical framework for its study. The description of the mechanisms are implicit to that.

 

Based on that the addition of "ongoing" is also unnecessary as the framework would define under which conditions evolution would be ongoing or not (such as under H-W equilibria).

Edited October 5, 2012 by CharonY

[Ronald Hyde]

I would eliminate belief from that statement as it implies a meta-view on the process. Whatever we call it (either Darwinism, new synthesis, Mocklefrock) describes the evolutionary process (to the extent we understand it) and forms the theoretical framework for its study. The description of the mechanisms are implicit to that.

 

Based on that the addition of "ongoing" is also unnecessary as the framework would define under which conditions evolution would be ongoing or not (such as under H-W equilibria).

 

I can understand what you want, but substituting the word Darwinism for Evolution in a language may not be so easy, everyone has to more or less agree on it for the

substitution to 'stick'. And I used the word ongoing to emphasize that it is still occurring and is happening now. As for the conditions under which it may occur, I've been

thinking about that too and I find them pretty complicated to define, not just needing mechanisms of inheritance, but ones that can change in particular ways. As for the

word 'belief' it only implies that it's a premiss that you must accept to understand biology.

[CharonY]

I am not sure whether you are referring to evolution as the process itself or the theoretical background explaining it. Modern synthesis (or Darwinism for that matter) refers to the latter. The conditions under which evolution occurs are pretty straightforward, actually. Predictive statements are the complicated part. Considering that evolution is a high level mechanism I do not see that it has to be an accepted premise of any sort. If you have a situation that does not conform to the H-W equilibrium evolution is pretty much an unavoidable consequence. There is not need to believe in that.

 

If I use the term as proposed by Ophiolite it would be correct to state that Darwinism describes the processes of evolution, pretty much the same way that Newtonian mechanics describe the movement of objects under the influence of forces. I doubt you would describe classical mechanics as the belief that an object dropped on earth will fall towards the ground, for example.

[Ronald Hyde]

I'm not thinking so much of explaining evolution as defining it, because once you've defined it, it pretty much 'explains' itself.

This may be part of why it was accepted so widely in the scientific community despite having no obvious mechanism.

[Jens]

(I agree to what have been stated by Dmaisky, Arete and CharonY above)

 

Darwin has based his concepts of evolution on animals and plants. Microbiology did not exist at this point in time. That there are occasionally more things than tiny mutations and selection (like cell mergers, horizontal gene transfer, hybridization) does not mean that anything is wrong with the findings before.

 

Even Woese who is in favour of a predominant role of horizontal gene transfer in the phase before Bacteria, Archaea and Eukarya have been formed (this is in debate -- I personally do not share this view), also states that it is not the predominant way of evolution afterwards.

 

The fact that for plants and animals (or better all multicellular Eukarya) clear trees can be obtained by analyzing the DNA for the ribosomal RNA definitely shows that there is a gradual evolution.

 

Or in a more scientific way:

If you analyze evolution trees of the complete genome for multicellular Eukarya you very rarely (if at all) have genes which show a clearly different tree (indicating horizontal gene transfer of any kind including species hybridization). So it is a clear exception.

So we do not need to make a religious believe out of it (and we never should ). We can measure what happened in the past.

 

If animals as different as dogs and cats never merged in the hundreds of millions years in the past, it is not a good assumption that this will happen in future (even if it definitely happend with microorganisms). And as soon as we actually find a case of real merge of complex multicellular species (in higher animals and plants) in the phylogenetic tree of a complete genome, I will change my mind (since it is not a religous believe ). This surely will be a nobel price.

[Ronald Hyde]

(I agree to what have been stated by Dmaisky, Arete anc Charon above)

If animals as different as dogs and cats never merged in the hundreds of millions years in the past, it is not a good assumption that this will happen in future (even if it definitely happend with microorganisms). And as soon as we actually find a case of real merge of complex multicellular species (in higher animals and plants) in the phylogenetic tree of a complete genome, I will change my mind (since it is not a religous believe ). This surely will be a nobel price.

 

I don't think you will find that. But you may find cases where a gene that degrades a particular insecticide is transferred from an insect to a bacterium

and then on to other insects. And 'sideways' transfer of genes may have been more common with simple bacteria because higher organisms have more

protective wrapping around their DNA.

[darryl88]

What, exactly, do you want commentary on? What is the point you wish to

discuss?

 

There is no point in repeating all of the same comments about non-Darwinian evolution or the extended synthesis becuase it seems two other users have already started a large debate about it on another forum and said many of the same things as me and cited the same papers as me. I suggest if users are interested to carry on the conversation to head over here. Cheers. http://www.thescienceforum.com/biology/30496-extended-evolutionary-synthesis.html#post358195

[Ronald Hyde]

There is no point in repeating all of the same comments about non-Darwinian evolution or the extended synthesis becuase it seems two other users have already started a large debate about it on another forum and said many of the same things as me and cited the same papers as me. I suggest if users are interested to carry on the conversation to head over here. Cheers. http://www.thescienc...html#post358195

 

I think we've pretty much discussed everything, and reached the conclusion that evolution is a process and that it's important to understand it's

mechanisms and that names and philosophical approaches are not so important.

 

But your comments are most welcome.

[Jens]

I don't think you will find that. But you may find cases where a gene that degrades a particular insecticide is transferred from an insect to a bacterium and then on to other insects.

 

I Agree.

 

And 'sideways' transfer of genes may have been more common with simple bacteria because higher organisms have more protective wrapping around their DNA.

 

Actually bacteria have specific proteins with the purpose to exchange genes. That is the reason why it is more common in Bacteria. It is their replacement for sexual reproduction.

[CharonY]

Technically, horizontal gene transfer is uncoupled from reproduction and is therefore not a replacement. Before the rise of sexual reproduction, the mechanisms for the transfer of genetic information between different individuals and reproduction were quite independent of each other.

[Jens]

Technically, horizontal gene transfer is uncoupled from reproduction and is therefore not a replacement. Before the rise of sexual reproduction, the mechanisms for the transfer of genetic information between different individuals and reproduction were quite independent of each other.

 

I agree. Sorry for my very unprecise wording. Let me try it with other words:

 

Sexual reproduction makes it possible to combine successful genes in one organism, which have evolved independently in seperate chains of individuals. Bacteria do not have sexual reproduction. But they also have a way to combine successful genes in one organism. They use transfer of genetic information facilitated by specifc proteins. So lateral gene transfer is obviously more common in bacteria.

[darryl88]

Hello,

 

I recently have been reading a lot of books on evolution and I have discovered many evolutionary mechanisms that are not usually discussed on internet forums. When we see talks on forums about evolution or other websites etc usually only natural selection, mutations or genetic drift is discussed as the mechanisms that cause evolution. But what if these mechanisms are not actually driving evolution? What if other mechanisms/processes are just as important or more important?

 

Here is a list of the mechanisms/processes I have found:

 

 

gene flow, genetic draft, genetic hitchhiking, horizontal gene transfer, endosymbiosis, symbiogenesis, paleopolyploidy (genome duplications), group selection, internal selection, kin selection, social selection, somatic Selection, autoevolution, molecular drive, niche construction, saltationism, self-organization, epigenetics, Semiotics, hybridization, natural genetic engineering, orthogenesis, nomogenesis, hopeful monsters, directed mutagenesis, morphogenetic fields, transposable element (jumping genes), hox genes, controlling elements, Phenotypic plasticity, Quantum evolution etc

 

Any opinions about any of these?

[ydoaPs]

For the most part, those aren't different mechanisms, but rather terms describing things the previously mentioned mechanisms do or how they work.

[darryl88]

For the most part, those aren't different mechanisms, but rather terms describing things the previously mentioned mechanisms do or how they work.

 

 

 

What makes you say that? Do you have some examples?

[Arete]

What makes you say that? Do you have some examples?

 

Gene flow, horizontal gene transfer and hybridization all describe the same process.

 

Stochastic evolution and genetic drift describe the same process.

 

etc.

[Ophiolite]

How many threads do you intend to start on the same topic darryl88? What is your aim? The majority of the mechanisms you have spoken of are recognised by the biological consensus and, indeed, were developed/discovered by the biological consensus. It is not earthshattering news to learn that evolutionary theory ..... evolves. Why do you think it is?

[darryl88]

The majority of the mechanisms you have spoken of are recognised by the biological consensus and, indeed, were developed/discovered by

the biological consensus.

 

Define the "biological" consenus. And actually most of those mechanisms are denied by the neo-Darwinian synthesis.

 

It is not earthshattering news to learn that evolutionary theory .....

evolves.

 

I have been saying this for a long time but users on internet forums only seem to mention genetic drift or natural selection and it is getting very boring seeing this becuase evolution is far more complex than just those mechanisms, why are all the other mechanisms and processes ignored and never mentioned? Can you explain?

Edited November 8, 2012 by darryl88

[ydoaPs]

And actually most of those mechanisms are denied by the neo-Darwinian synthesis.

 

How sneaky of those biologists to disagree with themselves!