Wednesday, June 3, 2009 | Reason : Evolution and Biology | print version

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When Evolution Is Not So Slow And Gradual

by Science Daily

Thanks to Scott for the link.
http://www.sciencedaily.com/releases/2009/06/090602133551.htm

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A new article in The American Naturalist finds that guppy populations introduced into new habitats developed new and advantageous traits in just a few years. This is one of only a few studies to look at adaptation and survival in a wild population.

A research team led by Swanne Pamela Gordon from the University of California, Riverside studied 200 guppies that had been taken from the Yarra River in Trinidad and introduced into two different environments in the nearby Damier River, which previously had no guppies. One Damier environment was predator-free. The other contained fish that occasionally snack on guppies.

Eight years after their introduction, the team revisited the Damier guppies to see what adaptive changes they might have picked up in their new environments. The researchers found that the females had altered their reproductive effort to match their surroundings. In the environment where predators were present, females produced more embryos each reproductive cycle. This makes sense because where predators abound, one might not get a second chance to reproduce. In less dangerous waters, females produced fewer embryos each time, thus expending fewer resources on reproduction.
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http://www.sciencedaily.com/releases/2009/06/090602133551.htm

Posted: Wednesday, June 3, 2009 | Permalink

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1. Comment #384385 by F_A_F on June 3, 2009 at 12:05 pm

Man, I really need to get some more guppies! Haven't had them since I was a kid....

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2. Comment #384388 by rod-the-farmer on June 3, 2009 at 12:20 pm

Now, this is just microevolution. Show me a croco-guppie, and I might believe in evolution. Well, no, I won't, I will just come up with another chimera.

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3. Comment #384429 by elpopstardo on June 3, 2009 at 2:18 pm

Yey for guppies.

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4. Comment #384440 by Mr DArcy on June 3, 2009 at 2:53 pm

This could be the living proof of the God of the Guppies!

Sorry I'm off!

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5. Comment #384446 by littletrotsky13 on June 3, 2009 at 3:20 pm

There's something similar in my biology textbook, although it only mentions colours in male guppies (in the predated waters the male guppies were plainer, in the safe ones they were more colourful, as an example of the sexual selection/survival trade-off).

In fact, seeing as they're in the same place, it's most probably the same experiment, just a
little further down the line.

But this is intersting, and expectable, that a more k-growth individuals (larger and fewer offspring)would dominate over r-species (smaller and more) whern the limiting factors are resource competition rather than predation.

We should probably see other things like a slightly increased size and lifespan over time as well, and possibly (like lake Victoria used to be) some diversification as well (I won't hold my breath for the last one though, as it's a small environment they're confined to)

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6. Comment #384490 by Anath on June 3, 2009 at 6:12 pm

@2

You think they would sell crocoguppies in pet stores? I want one.

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7. Comment #384492 by Lord Osis on June 3, 2009 at 6:25 pm

4. Comment #384440 by Mr DArcy "This could be the living proof of the God of the Guppies!"

Spot on. God looks after guppies too - she's been very busy of late...

"In the long run, survival of juveniles is crucial to the survival of the population, the researchers say."

I wonder if that's a direct quote?

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8. Comment #384523 by Arjen on June 3, 2009 at 9:15 pm

This doesn’t surprise me one bit. A few years ago, there was a study done at North Sea cod that had a similar conclusion. Under the pressure of over fishing, the researchers found that cod became sexually mature faster and at a smaller size. Originally cod was sexually mature at 4 years of age and now at 3 (if I remember correctly). It was also noted that cod didn’t grow as large as it usually did. The researcher explained that this had happened because the large cod that reproduced at a later age had a higher chance of being caught before reproduction than smaller cod that were sexually mature at an earlier age. Give it a few generations and a lot of over fishing and presto, the overall population of North Sea cod is now generally smaller and sexually mature at a younger age. There is also a big chance this is a permanent change and that the monster cods that were caught 50 years ago might never get back.

Change within 50 years with notable differences in size. Counts as pretty fast evolution for me and it is because of human influence in the environment.

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9. Comment #384575 by Chris Davis on June 4, 2009 at 2:09 am

I know this is nitpicking, but it would have been nice if the article had made the point that the adaptations were the result of some fish surviving their environment.

The text suggests quite strongly that the fish made the adaptation in order to survive.

Yes, it's just shorthand for the apparently purposeful progress of evolution, but in a public article it would be wise to give a nod to the fact that the actual process works the other way around. The article might be read by children or creationists, after all.

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10. Comment #384595 by Degsy on June 4, 2009 at 4:04 am

Comment 384575 by Chris Davies

I totally agree with you on that one Chris. The article does imply that the changes observed in the guppy populations were intentional changes made by the fish in order to survive. This is obviously not the case, as it is the selective pressures in their new environment that has brought about the observed changes in behavior.

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11. Comment #384600 by weavehole on June 4, 2009 at 4:20 am

What a wonderfully simple idea from these researchers. I doff my prodigiously proportioned cap to them.

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12. Comment #384605 by weavehole on June 4, 2009 at 4:29 am

Re: comment 8 by Arjen

Cod are now sexually mature at 3 years old? Tell me is this good or bad news for pederast priests in the North Sea diocese of the e-pisces-copalian Roman Cod-tholic Chperch.

(sorry )

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13. Comment #384681 by squinky on June 4, 2009 at 6:39 am

Chris Davis

I wholeheartedly agree. I hate reading this inverted way of presenting evolution every time as if all female guppies had a meeting on how to adapt their behavior for survival.

It would be interesting to know (but difficult to exhaustively observe) what percentage of the guppies actually changed their reproductive cycle (i.e. tried a new reproductive strategy or learned a new behavior) vs. how many just died off and it was the 2% in the general population that were already trying the new many-embryo strategy that were selected for and overtook the population.

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14. Comment #384745 by NewEnglandBob on June 4, 2009 at 8:47 am

Guppies 1, creationists 0

I always knew guppies were smarter than creationists.

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15. Comment #384749 by Tyler Durden on June 4, 2009 at 8:57 am

Slightly OT:

Examples of pottery found in a cave at Yuchanyan in China's Hunan province may be the oldest known to science.

By determining the fraction of a type, or isotope, of carbon in bone fragments and charcoal, the specimens were found to be 17,500 to 18,300 years old.

Poor YECs. So much science, so few gaps.

http://news.bbc.co.uk/1/hi/sci/tech/8077168.stm

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16. Comment #384859 by Mr DArcy on June 4, 2009 at 1:23 pm

Poor YECs. So much science, so few gaps.

I'm not so sure about the poor, apart from their poverty of ideas. Try this guy for size:
http://en.wikipedia.org/wiki/Howard_Ahmanson,_Jr

I believe he is one of the supporters of the Discovery Institute.

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17. Comment #384875 by Simon Wilson on June 4, 2009 at 2:09 pm

I agree with Chris, degsy and squinky.

And before I started visiting this site, I wouldnt have thought that there was anything wrong with the article.
(What a great example of evolution! Now I just need to pass this information on to my children - via memes I suppose?).

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18. Comment #387037 by InfuriatedSciTeacher on June 11, 2009 at 6:31 pm

It appears to be difficult for people to avoid assigning agency, even when discussing a directionless process. I would hope that whoever wrote this article would have been mindful of something like that, but I've caught myself speaking in the same manner while teaching and had to add the disclaimer "remember, they survive because they had the right adaptation, not because they decide to adapt." Shades of Lamarck creep back in if you're not careful.

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