Friday, October 30, 2009 | Science : Genetics | print version

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Junk DNA Mechanism That Prevents Two Species From Reproducing Discovered

by ScienceDaily

Thanks to rod-the-farmer for the link.
http://www.sciencedaily.com/releases/2009/10/091026220018.htm

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When two populations of a species become geographically isolated from each other, their genes diverge from one another over time.

Eventually, when a male from one group mates with a female from the other group, the offspring will die or be born sterile, as crosses between horses and donkeys produce sterile mules. At this point, they have become two distinct species.

Now, Cornell researchers report in the October issue of Public Library of Science Biology (Vol. 7, No. 10) that rapidly evolving "junk" DNA may create incompatibilities between two related species, preventing them from reproducing. In this case, the researchers studied crosses between closely related fruit flies, Drosophila melanogaster and D. simulans. Nearly 100 years ago, scientists discovered that when male D. melanogasters mate with female D. simulans, normal males survive, but the female embryos die.

"It has remained an unsolved problem," said Patrick Ferree, the paper's lead author and a postdoctoral researcher in the lab of co-author Daniel Barbash, an assistant professor of molecular biology and genetics. "The question is, what are the elements that are killing these female hybrids and how are they doing that?"
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http://www.sciencedaily.com/releases/2009/10/091026220018.htm

Posted: Friday, October 30, 2009 | Permalink

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1. Comment #428379 by Mitch Kahle on October 30, 2009 at 7:50 pm

Can a Republican mate with an ass?

There seems to be plenty of evidence that they can.

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2. Comment #428385 by Rumraket80 on October 30, 2009 at 8:17 pm

Every time I read something about fruitflies and genetic research I am reminded of Sarah Palin and the potential catastrophe she would have made as vice president.

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3. Comment #428386 by caraz84 on October 30, 2009 at 8:22 pm

i'm confused does this mean a mongrel dog is infertile???

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4. Comment #428393 by Sally Luxmoore on October 30, 2009 at 8:45 pm

Comment #428386 by caraz84

i'm confused does this mean a mongrel dog is infertile???

No, because pedigrees are not separate species. All dogs are still the same species and can therefore interbreed - though it would be inadvisable to try it with breeds at the extremes of size, for example.

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5. Comment #428394 by Mitch Kahle on October 30, 2009 at 8:50 pm

@caraz84
"i'm confused does this mean a mongrel dog is infertile???"

The mongrel is a mixed-breed dog. All dog breeds are the same species, and thus able to mate and reproduce.

As for Sarah Palin . . . I'm not sure, clearly she's not evolving.

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6. Comment #428413 by TIKI AL on October 30, 2009 at 10:59 pm

Mitch @ 1: "Can a Republican mate with an ass?"

Yes, and unfortunately their offspring are NOT sterile.

If you are looking for an interesting hybrid, may I suggest Bengal cats. (Asian leopard cat/siamese)

They are much more intelligent and make better pets than Asslicans.

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7. Comment #428415 by mordacious1 on October 30, 2009 at 11:22 pm

Hmmm...if the definition of "junk" DNA is that it's DNA that now has no purpose, then if it's found that it keeps species from interbreeding, is that not a purpose? I suppose that it doesn't have the original purpose, but that can be said of a lot of DNA, no?

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8. Comment #428416 by Shane McKee on October 30, 2009 at 11:39 pm

Oh, how creationists/ID-iots love finding that "junk" DNA isn't useless! Of course we have known that "junk" DNA has lots of "function" (none of which was worked out by creationists, of course), but it's particularly sweet to see how its "function" ties in with evolution.

This is interesting stuff; it may have relevance to the fascinating phenomenon of sympatric speciation, where species diverge, even though they occupy the same geographic locale, and in theory should be able to interbreed OK. but they can't/don't. Lovely!

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9. Comment #428427 by Quine on October 31, 2009 at 12:07 am

Comment #428415 by mordacious1:

Hmmm...if the definition of "junk" DNA is that it's DNA that now has no purpose, then if it's found that it keeps species from interbreeding, is that not a purpose?

I would think of it more as a loss of capability rather than the gain of deficiency. While two populations are separated, there is no selection pressure to maintain the capability to interbreed (selection pressure which keeps sweeping out mutations deleterious to breeding within the separate populations). If interbreeding capability is lost, and some are thrown back together, those who spend energy attempting to interbreed may be at enough of a disadvantage to be subject to losing in competition with those who select mates that are genetically closer. That would select for those who don't try it. Once they all stop trying there is, again, no selection pressure to evolve back to interbreeding capability.

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10. Comment #428434 by Sally Luxmoore on October 31, 2009 at 12:43 am

Comment #428394 by Mitch Kahle

As for Sarah Palin . . . I'm not sure, clearly she's not evolving.

She has, however, passed on more of her DNA to the next generation (and even a third generation already) than most of us have - and that is all that counts!
You want to beat her? You've got to outbreed her!

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11. Comment #428435 by Branko on October 31, 2009 at 12:45 am

I beat her by one.

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12. Comment #428451 by j.mills on October 31, 2009 at 3:02 am

Okay, further to Quine's point that something like this might arise as a difference between separated populations because no selection pressure resists it... But if that's so, it is not that a particular mechanism has been selected, only that an incompatibility has arisen. Therefore, is there any reason to suppose that the fertility impediment between species A and B would be the same as that between C and D? In other words, might the incompatibility between each pair of closely related species be unique to that pair, rather than the 'same difference' in each case? It would follow that this research is only an indicator of the kinds of difference that might arise, rather than a universal mechanism like a HOX gene. Thoughts?

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13. Comment #428462 by Quine on October 31, 2009 at 4:56 am

Comment #428451 by j.mills:

... only that an incompatibility has arisen.

I think of it as a capability that has been lost. The reason I make the distinction is that we are always pointing out to Creationists that mutation followed by Natural Selection can generate new design information, whereas in this case the loss of capability is, in fact, from the increase of entropy they so love to try to hold against us.

Therefore, is there any reason to suppose that the fertility impediment between species A and B would be the same as that between C and D?

No, I would not expect A and B to differ the same way that C and D differ except as the respective distributions of random mutations may overlap. However, I have not seen any data on this or even know if someone is looking at it.

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14. Comment #428472 by carbonman on October 31, 2009 at 6:29 am

This is interesting, focusing thought as it does upon loaded words like 'purpose' and 'junk' as applied to DNA. Bottom line is, DNA tends to pop up in whatever forms get copied most, and if that causes a fork in Eden's River then so be it.

The role of junk DNA in speciation came up in Science Daily about 4 years ago, linked on the same page as this story.
http://www.sciencedaily.com/releases/2005/10/051020090946.htm

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15. Comment #428476 by russkid on October 31, 2009 at 7:02 am

Can a Republican mate with an ass?

There seems to be plenty of evidence that they can.

They can, and win because liberals have not yet figured out how reproduce homosexually.

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16. Comment #428506 by alexhouse on October 31, 2009 at 12:38 pm

It seems to me that posters aren't taking this very seriously; Isn't this a key finding on the mechanism of speciation?

I've always wondered how the facility to speciate evolved - what advantage does not being able to reproduce with a distant relative bring? This facility seems to be much reduced in domesticated species so that quite different varieties can interbreed - on the other hand, is this just because it is a direct result of time based deterioration in the junk DNA?

Cool stuff.

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17. Comment #428519 by j.mills on October 31, 2009 at 1:31 pm

alexhouse:

this facility seems to be much reduced in domesticated species so that quite different varieties can interbreed

That's because the populations aren't really isolated - breeders keep cross-breeding and experimenting. If we destroyed all dogs except great danes and chihuahuas, then without artificial intervention they would be bound to become genetically incompatible eventually; but as things stand there are all kinds of intermediate mongrels that unite all dogs into one breeding population. Also, although domestication is (these days) directed, and thus probably more rapid than 'natural' selection, it's still taken place over a much shorter timescale than in natural speciation.

what advantage does not being able to reproduce with a distant relative bring?

It doesn't need to: it only has to bring no disadvantage not to have that facility. Mutations that cause divergence aren't selected against because the host organism is not disadvantaged in the local population.

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18. Comment #428533 by TIKI AL on October 31, 2009 at 2:29 pm

How surprising that a person who is on the record against liberals, gays, and health care reform can't string a complete sentence together:

"They can, and win because liberals have not yet figured out how reproduce homosexually." ...russkid @ 15.

If it talks like a troll, and hates like a troll...

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19. Comment #428568 by RosaleneS on October 31, 2009 at 4:50 pm

I would like to respond to Quine regarding “junk DNA.” I believe your definition is incorrect. Junk DNA would best be defined as that concerning which we are ignorant. Perhaps you should consider some of the positive exploration into the function of the DNA. I could recommend some reading material that does not arbitrarily eliminate lines of inquiry because of personal preference. Would you not agree that truth is truth and to defy laws of nature often produces fatal results?
I suggest that being an intellectually fulfilled atheist on the basis of Darwinian naturalism might have been possible in the 19th century, however to continue to hold on to this argument in the 21st century constitutes denial of the facts and refusal to explore research along productive lines of questioning. Countering with insult and innuendos only betrays the lack of a cogent argument.
I would challenge you to read Dr. Steven Meyer’s most recent book concerning the construction of the cell.

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20. Comment #428576 by dumbcountryhick on October 31, 2009 at 5:18 pm

FORMAT ERROR: X CHROMOSOME D. MELANOGASTER

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21. Comment #428583 by Quine on October 31, 2009 at 5:47 pm

Comment #428568 by RosaleneS:

I would like to respond to Quine regarding “junk DNA.” I believe your definition is incorrect. Junk DNA would best be defined as that concerning which we are ignorant. Perhaps you should consider some of the positive exploration into the function of the DNA.

?? I did not mention "junk DNA" so what exactly are you referring to?

I suggest that being an intellectually fulfilled atheist on the basis of Darwinian naturalism might have been possible in the 19th century, however to continue to hold on to this argument in the 21st century constitutes denial of the facts and refusal to explore research along productive lines of questioning.

?? What was that about and where did it come from?

P.S. See these notes of recent research by Eric Lander put up by PZ.

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22. Comment #428588 by phil rimmer on October 31, 2009 at 6:09 pm

Comment #428583 by Quine

?? What was that about and where did it come from?

Dunno. But we know where its headed....

http://en.wikipedia.org/wiki/Stephen_C._Meyer

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23. Comment #428594 by Quine on October 31, 2009 at 6:22 pm

Comment #428588 by phil rimmer:

Dunno. But we know where its headed....

(SSSSH! I wanted her to step into it deeper first.)

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24. Comment #428605 by InfuriatedSciTeacher on October 31, 2009 at 7:14 pm

Flagged as offensive... try to be less of a scumbag next time.

Would you not agree that truth is truth and to defy laws of nature often produces fatal results?

No, I wouldn't agree... you're insisting on a positivist ideal of truth that went out the window with Hume in the 18th century. And while it's nice to have alternate explanations, I/we don't need the science to demonstrate that your religious belief is inane... it does that all on its own. Truth is our best effort at understanding the world, and while things can be false it's not possible to definitively state something as true, merely very close to it. That's a nice case of projection you have there too, have you thought about getting that treated?

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25. Comment #428609 by alexhouse on October 31, 2009 at 8:04 pm

I think a couple from the opposition have realised the importance of this finding. Proof of time based enforced speciation based on degradation of junk DNA is absolutely key. The argument for speciation by semi-permeable boundaries - or even just distance always seemed a bit weak. We had to assume it happened but.... Add this to the model and I think it is unassailable.

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26. Comment #428614 by phil rimmer on October 31, 2009 at 8:46 pm

Quine

Glutton!

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27. Comment #428618 by Quine on October 31, 2009 at 9:11 pm

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28. Comment #428627 by phil rimmer on October 31, 2009 at 10:03 pm

For punishment.

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29. Comment #428646 by crookedshoes on November 1, 2009 at 1:25 am

the "junk" label is akin to the popular idea that 90% (or some high number) of the brain does nothing. I always think that if you analyzed electrical wires and telephone poles, you'd conclude that telephone poles do very little. But, they do a whole bunch. same with the "other percent of your brain" and all the "junk" DNA.

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30. Comment #428653 by RPG070012 on November 1, 2009 at 1:56 am

Some humans beget starile children, is there something to this?

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31. Comment #428656 by j.mills on November 1, 2009 at 2:37 am

First post from RosaleneS smacks of Dembski-points... I look forward to the second.

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32. Comment #428657 by Quine on November 1, 2009 at 2:49 am

Comment #428656 by j.mills:

I look forward to the second.

I suspect it was a drive-by.

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33. Comment #428661 by russkid on November 1, 2009 at 3:07 am

15. Comment #428476 by russkid on October 31, 2009 at 7:02 am

Flagged as offensive... try to be less of a scumbag next time.

Back at you.

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34. Comment #428699 by TIKI AL on November 1, 2009 at 3:55 pm

"Back at you." = I know you are but what am I?

I haven't seen the vaunted "kindergarten defense" used in quite some time.

If your jammies have a trap door on the back, please accept my apology for being strident.

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35. Comment #428748 by BillySands on November 1, 2009 at 7:59 pm

I saw an advert for Meyer's book saying he had a peer reviewed scientific paper on the subject. Actually, it was a review, not an original research article.

The review was of course bollocks http://pandasthumb.org/archives/2004/08/meyers-hopeless-1.html and apparently proper peer review protocol was not follwed and seemes to have been allowed without review by an ID sympathser http://en.wikipedia.org/wiki/Sternberg_peer_review_controversy

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36. Comment #428796 by russkid on November 1, 2009 at 10:55 pm