Convergent Evolution

[Jennifer]

See here.

A gene in Asian monkeys that may have evolved as protection against a group of viruses that includes HIV has been identified by Harvard Medical School researchers, who add that their finding suggests the current AIDS epidemic is not a new kind of scourge.

....This is the second time a TRIM5-CypA hybrid gene has been identified in monkeys. The other one -- TRIMCyp -- was found in South American owl monkeys in 2004. But it's not likely that these two gene combinations arose from a single common ancestor, the Harvard researchers said...

This sort of thing is discussed all the time in the lab -- examples of convergent evolution, where a particular type of gene mutation is so beneficial that it arises (or very similar genes arise in separate unrelated species.

The eye is a similar process... where many eyes as we know them are wired in a backwards manner (the optic nerve runs into the eyeball on its way out, rather than just being affixed to the outside)... but a few unconnected marine species exist where the eye is wired in a "sensible way" -- suggesting that the eye structure evolved concurrently on parallel tracks, and the variation between attributable to the original random mutations.

Thoughts? Comments?

[Randomnity]

Yep, cool isn't it? It's remarkably common, actually...one of the many cool things about evolution.

That monkeys have already evolved some form of protection against AIDS though, that's pretty interesting. Although it sounds like it's more like protection against a whole family of less recent viruses (I don't remember exactly what lentiviruses are) that just happens to include AIDS.

[elfinchilde]

from the viewpoint of one who majored in microbiology:

convergent evolution is hardly a surprise. Because by Darwinian principle: Only the fittest survive, and adaptability is the key to survival. Hence, in all species, the genes that code for a specific trait that ensures survival will live on, whilst weaker members possessing 'undesirable traits' will die off. This ensures that the strongest live on to pass on their genes.

So if there was a virus that could target more than one species, for instance, then naturally, all the species which the virus targets will inevitably possess same/similar genes that confer protection against the virus. Because those species that did not, would have died out. Hence different species would posses the same/similar genes that confer a desirable trait.

Point of information: Monkeys developing genes against HIV. It has been postulated, but never proven, that AIDS (more specifically, the HIV virus) came about due to bestiality, originating from Africa, and transported throughout the world by sailors. The monkey equivalent is SIV--simian immunodeficiency virus. That has been around and acknowledged for decades, if not centuries.

HIV, however, only came into light in 1978, when a sailor was warded with a 'strange disease' in San Francisco. Subsequently, the cases exploded, and today, you have the AIDS pandemic.

So the possibility is that the virus simply mutated so as to be better virulent in humans, as compared to simians (ie, monkeys). Hence the parallel genes that protect against HIV--and SIV--exist in other species.

Additional information: (yes, a digression)
HIV is interesting in that it is a retrovirus--unique amongst the viruses in that it can survive both in DNA and RNA form: with the DNA form being a latent stage, explaining one of the reasons why HIV is so difficult to target in medical treatment.

Most living species possess only DNA, with RNA being a short phase when cells are reproducing. However, certain viruses genomes are made of RNA only. These are more rapidly mutating, as they lack what is known as a proof-reading function, which the DNA replicase enzyme possesses. Hence, there is less fidelity to the 'original script', which allows for greater species variation. Therein the second 'advantage' the HIV virus has: rapid RNA mutation.

[Jennifer]

Originally Posted by elfinchilde

from the viewpoint of one who majored in microbiology:

Neat, thanks!

convergent evolution is hardly a surprise. Because by Darwinian principle: Only the fittest survive, and adaptability is the key to survival. Hence, in all species, the genes that code for a specific trait that ensures survival long enough to reproduce will live on, whilst weaker members possessing 'undesirable traits' will die off before they can reproduce. This ensures that the strongest live on to pass on their genes.

Small tweak just to clarify it for others. (see bold)

I think one of the points where people get confused (and why I enjoyed this article) is that they are operating under the notion that almost all mutation will be bad mutations, therefore a "good change" doesn't seem believable to them.

Not only are good changes possible, but they are replicated in various species and actually do occur.

[elfinchilde]

Originally Posted by Jennifer

Neat, thanks!



Small tweak just to clarify it for others. (see bold)

I think one of the points where people get confused (and why I enjoyed this article) is that they are operating under the notion that almost all mutation will be bad mutations, therefore a "good change" doesn't seem believable to them.

Not only are good changes possible, but they are replicated in various species and actually do occur.

No problem about the tweaking, thanks! I sometimes type stream-of-consciousness. So editing is much appreciated.

And yes. Mutations by themselves are never good or bad per se. It is what nature dictates for survival, that says if it is a good or bad mutation.

Using HIV again as the example (since it's quoted already), there are some people around who are naturally more resistant to the virus than others, due to some genes which they possess. In effect, this can be considered a good mutation, handed down from generations, and showing itself only when HIV surfaced in the human population.

H5N1 (bird flu) is the other example. There are some people, as well as birds, and other animal reservoirs, which have evolved/possessed immunity to this deadly disease. This is again due to genetic mutation--or more precisely, genetic variation. Sometimes it's rapid, sometimes it's not. All depends on the species, and the rate of the disease spreading.

note: because of the DNA/RNA thing---genetic mutation tends to occur much, much more slowly in animals, including humans, than in bacteria and viruses. In that sense, the microbes have one-up on us. Plus, one generation in humans is about 25 years, whilst for bacteria/viruses, it may be as short as a few hours. So generational mutation occurs much more swiftly in a same time frame for bugs than for us.

[Jasz]

thanks for the interesting discussion guys. now lunch is over.

[Nocap]

Originally Posted by Jennifer

See here.



This sort of thing is discussed all the time in the lab -- examples of convergent evolution, where a particular type of gene mutation is so beneficial that it arises (or very similar genes arise in separate unrelated species.

The eye is a similar process... where many eyes as we know them are wired in a backwards manner (the optic nerve runs into the eyeball on its way out, rather than just being affixed to the outside)... but a few unconnected marine species exist where the eye is wired in a "sensible way" -- suggesting that the eye structure evolved concurrently on parallel tracks, and the variation between attributable to the original random mutations.

Thoughts? Comments?

I'm not sure I understand: You're saying that the eye was two separate entities which eventually became one, to, presumably, serve a stronger or at least more important function? And that this is parallel (not timewise) to the way the anti-aids gene in those asian monkeys developed?

If that's the case then ears are largely the same way are they not?

[Jennifer]

Originally Posted by Nocapszy

I'm not sure I understand: You're saying that the eye was two separate entities which eventually became one, to, presumably, serve a stronger or at least more important function? And that this is parallel (not timewise) to the way the anti-aids gene in those asian monkeys developed?

If that's the case then ears are largely the same way are they not?

No. I'm saying the structure of the eye did not evolve just once. It looks like two separate strands of organisms separately developed it, as a response to environmental needs. But in the one strand, the optic nerve wired one way, and in the other, the strand wired backwards. Both work and are similar... but the specifics differ. (I think I read this in Dawkins' "The Blind Watchmaker.")

Just like with these monkeys, two different strands developed the same sort of useful protein separately.

[Nocap]

Of course

[Athenian200]

I'm afraid I didn't garner much from this. It seems like all I can infer is that similar environmental pressures can cause unrelated organisms to develop similar adaptations independently, and that seems fairly reasonable to me. What's strange about that?

Two scientists independently invented semiconductors around the same time, with the main difference being that one was produced with Germanium, and the other with Silicon... seems like a similar scenario in a way.