Horizontal gene transfer contradicts neodarwinism?

[PIT2]

Here a newsstory about horizontal gene transfer:

Horizontal gene transfer (HGT) is a cross-species form of genetic transfer. It occurs when the DNA from one species is introduced into another. The idea was ridiculed when first proposed more than 50 years ago, but the advent of drug-resistant bacteria and subsequent discoveries, including the identification of a specialized protein that bacteria use to swap genes, has led to wide acceptance in recent years.
http://physorg.com/news89292896.html

Compare with neodarwinism:

Neo-Darwinism generally denotes the integration of Charles Darwin's theory of the evolution of species by natural selection, Gregor Mendel's theory of genetics as the basis for biological inheritance, random genetic mutation as the source of variation, and mathematical population genetics.
http://en.wikipedia.org/wiki/Neodarwinism

Since gene swapping by organisms causes genetic variation, does this contradict neodarwinism which claims genetic variation is caused by random mutations?

 

[jim mcnamara]

HGT had another name 40 years ago. It was a done deal then. It was known that unrelated bacteria species could sometimes acquire traits from each other. You have virus DNA in some of your cells now, as we speak.

"Random genetic mutation" means random changes to genes and gene expression. Is it limited to mean that the mutation is by base-mess-ups only where the source DNA is from the organism itself? No. Crossing over, incomplete meiotic conjunction (meiotic drive), partial penetrance: all contribute to variation and to variable gene expression.

We are are all just leaky bags of chemicals - all us living things. Among the chemicals us organisms leak is DNA. It's in human saliva and fingerprints. The smaller the organism the sloppier things get. At the single cell procaryotic level it's close to chaos.

So I don't see a connection.

 

[PIT2]

HGT had another name 40 years ago. It was a done deal then. It was known that unrelated bacteria species could sometimes acquire traits from each other. You have virus DNA in some of your cells now, as we speak.

I posted the wrong source link in my first post. The story says that the idea was ridiculed 50 years ago, which is perhaps why u say it was a done deal. However, it now seems to be gaining acceptance.

"Random genetic mutation" means random changes to genes and gene expression. Is it limited to mean that the mutation is by base-mess-ups only where the source DNA is from the organism itself? No. Crossing over, incomplete meiotic conjunction (meiotic drive), partial penetrance: all contribute to variation and to variable gene expression.

...

So I don't see a connection.

I know wikipedia can be an unreliable source, but in the article about symbiogenesis it states:

It is a fundamental principle of classical neo-Darwinism, or population genetics theory, that mutations arise one at a time and either spread through the population or not, depending on whether they offer an individual fitness advantage. There is a major body of scientific work, both theoretical and experimental, based on this paradigm. Those who have worked in the field tend to regard its foundation as unassailable.

Nevertheless, the neo-Darwinist perspective remains vulnerable to challenges like that of Margulis because its experimental support comes overwhelmingly from the laboratory, not from the wild. We understand clearly how artificial selection works in the laboratory, but there is legitimate controversy over whether nature's laboratory works in just this way. Indeed, genome mapping techniques have revealed that family trees of the major taxa appear to be extensively cross-linked—possibly due to lateral transfer of genes carried by bacteria, as Margulis predicted.http://en.wikipedia.org/wiki/Symbiogenesis

Also in other sources people have written about HGT as being a new paradigm, or 'a revolution in biology'. Like this one:

Biology's next revolution
Here we explain why we foresee such a dramatic transformation, and why we believe the molecular reductionism that dominated twentieth-century biology will be superseded by an interdisciplinary approach that embraces collective phenomena.
http://www.nature.com/nature/journal/v445/n7126/full/445369a.html

 

[russ_watters]

Since gene swapping by organisms causes genetic variation, does this contradict neodarwinism which claims genetic variation is caused by random mutations?

Swapping genes doesn't add any diversity to the gene pool, so there must still be a way to generate new genes.

 

[Moridin]

does this contradict neodarwinism which claims genetic
variation is caused by random mutations?

Swapping genes doesn't add any diversity to the gene pool, so there must still be a way to generate new genes.

Wikipedia is not a reliable source to acquire accurate information. What you are speaking of is the Synthetic Theory of Evolution¹. Mutations is not the only source of genetic variation or diversity. There is also recombination and gene flow². These two is a major part of the increase of genetic variation.

¹ http://anthro.palomar.edu/synthetic/default.htm
² http://www.talkorigins.org/faqs/faq-intro-to-biology.html

 

[russ_watters]

Your two links contradict each other on recombination: the first says it does not add new alleles and the second says it does.

Gene flow, though does not create new genes (as said in your link), it just moves existing ones from on species to another. That creates diversity within a species, but doesn't change the total number of genes in the biosphere. Maybe that seems like splitting hairs, but when the biosphere was all bacteria and other single cell organisms, the total number of genes in the biosphere was pretty limited and creating new ones was important.

In any case, I think the problem with the OP is simply a misreading of the wik article. Hairsplitting over definitions and particulars aside, the article does mention both recombination and gene flow and links separate articles that discuss them in more detail, including discussing horizontal gene transfer. No contradictions to be found.

 

[jim mcnamara]

russ -
gene flow is usually defined as between individuals of the same species - but individuals in different populations. Not usually between members of different species.

And. Gene flow can add new genes to a population, if not a species.

 

[PIT2]

In any case, I think the problem with the OP is simply a misreading of the wik article. Hairsplitting over definitions and particulars aside, the article does mention both recombination and gene flow and links separate articles that discuss them in more detail, including discussing horizontal gene transfer. No contradictions to be found.

My question was based on the wiki article of symbiogenesis. The newsarticle about horizontal gene transfer last week (the one in OP)reminded me of it.

Symbiogenesis is the merging of two separate organisms to form a single new organism. The idea originated with Konstantin Mereschkowsky in his 1926 book Symbiogenesis and the Origin of Species, which proposed that chloroplasts originate from cyanobacteria captured by a protozoan. Today both chloroplasts and mitochondria are believed to have such an origin; this is the endosymbiotic theory.

In Acquiring Genomes: A Theory of the Origins of Species, biologist Dr. Lynn Margulis argued that symbiogenesis is a primary force in evolution. According to her theory, acquisition and accumulation of random mutations are not sufficient to explain how inherited variations occur; rather, new organelles, bodies, organs, and species arise from symbiogenesis. Whereas the classical interpretation of evolution (neo-Darwinism) emphasizes competition as the main force behind evolution, Margulis emphasizes cooperation.
http://en.wikipedia.org/wiki/Symbiogenesis

HGT supports margulis theory of symbiogenesis, but if it doesn't contradict neodarwinism then i wondered how her theory of symbiogenesis does.

There are some parts of neodarwinism that seem to be assaulted by HGT. The nature article (which is no longer available for free) said that the concept of 'species' was no longer valid. And other sources say that the concept of a 'common ancestor' was also challenged by it, and that the tree of life wasnt really a tree anymore but more like a spiderweb.