Thursday, May 14, 2009

Biology Query

So here's something I've wondered about for a long time:

Suppose that the endosymbiotic hypothesis is true. Doesn't that mean that there has been at least some inheritance of acquired traits?

Inquiring minds want to know...


Blogger The Mystic said...


8:23 AM  
Blogger Winston Smith said...


9:22 AM  
Blogger Unknown said...

I certainly don't know enough to answer your question, but apparently our reading interests are running along in parallel to some degree. I'm working my way (or perhaps better, stumbling my way) through "The Organic Codes: An Introduction to Semantic Biology," by Marcello Barbieri. If you look at "Life is Semiosis", my reasons for being interested in this guy will be obvious.

The Rev.

10:06 AM  
Anonymous The Dark Avenger said...

I've been familiar with this concept since it was known as the Margulis hypothesis, and even though the Wiki has raised it to the dignity of a theory, using two separate hypothesis for support is a bit weak for a theory as such.

So, that's #1, I don't think much of the idea in the first place.


It is also believed that these endosymbionts transferred some of their own DNA to the host cell's nucleus during the evolutionary transition from a symbiotic community to an instituted eukaryotic cell. This hypothesis is thought to be possible because it is known today from scientific observation that transfer of DNA occurs between prokaryotic species, even if they are not closely related. Prokaryotes can to take up DNA from their surroundings and have a limited ability to incorporate it into their own genome.This is, BTW, how drug-resistance gets transmitted from bacteria to bacteria, via plasmids.

It's not considered an 'acquired characteristic' than an example of acquired DNA that then is replicated and expressed.

1:21 PM  
Blogger Winston Smith said...

Yo, Rev...I read the comment before I saw who left it, and my heart leapt when I thought I'd encountered an unknown weirdo out there interested in such things...

...but it was only you...

1:30 PM  
Blogger Winston Smith said...

Thanks, DA.

But I remain the idea that just because *some* DNA from the endosymbiots transferred into the host (or whatever it's called)...because that sounds like a cheat.

I suppose the question goes something like this: Cell C gets another cell, c, lodged inside it. C's offspring, C', ends up with a cell-like thingy, c', inside *it*. How did the trait *having a c/c'-ish thing inside you* get passed from C to C'? Solely in the normal ways + c passing genetic material into C? Or was there anything else involved? If the latter, it'd sound like inheritance of acquired traits to me.

The above undoubtedly contains several confusions.

1:36 PM  
Blogger lovable liberal said...

The implication of lots of biology being done now, not just the endosymbiotic hypothesis but everything recombinant, is that there's an awful lot of biochemistry going on that doesn't fit into the traditional species concept. Bacteria exchange genetic material all the time, so for instance antibiotic immunity can leap from species to species. Species expression itself is very plastic, to the point at which Lynn Margulis, last I read from her, discounts species distinctions between bacteria.

I don't know enough to judge her claim, but even the species concept for macrofauna is fuzzy, witness interbreeding between closely related species.

There's just no denying that inheritance of acquired DNA/RNA happens. We're even trying to harness it via gene therapies that are heritable.

What still isn't heritable is the acquisition by individual effort of phenotypes. Maybe a better way to state what's true would be: acquired phenotypes do not enter the genome.

But what do I know, I've just read a few popular books. Maybe you should ask PZ Myers.

5:31 PM  

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