Evolution, fruit flies, and counting

Don’t let any creationist tell you complex things don’t come from simple precursors:

US and Canadian researchers have evolved a population of fruitflies that can count. The result, presented on 9 July at the First Joint Congress on Evolutionary Biology in Ottawa, Canada, supports the notion that the neural mechanisms underlying basic arithmetic skills first emerged hundreds of millions of years ago. It could also eventually offer a key to understanding why some people have problems with numbers…

During a 20-minute training period, flies were exposed to either two, three or four flashes of light — two and four flashes coincided with a vigorous shake administered by placing a electric toothbrush next to the box containing the flies. After a brief rest, the flies were returned to box and shown the light flashes. Despite a dislike for being shaken, most of the flies were not able to learn to associate the negative stimulus with the number of flashes. But 40 generations later, they could.

The researchers caution that the work is preliminary and that they do yet know what genetic changes are behind the insects’ evolved number sense.

What I find interesting is exactly how this constitutes selection pressure. The flies certainly don’t like being shaken, but that’s entirely irrelevant if there isn’t some sort of reproductive advantage to be had from recognizing when the shaking will occur. Clearly there is, and we could speculate all day long as to why flies that associate the flashes with negative stimulus pass on more of their genes than the other flies, but I would like to see some experimental data showing the details. Does shaking disorient the flies? Does it interrupt the mating process? Does it affect fertility? Perhaps the paper that comes from all this can shed some light.

Now excuse me while I go murder the fruit flies that appear to have evolved to make my kitchen just awful for the past week.

Advertisement

Your genes, sleep, fruit flies, mice, and Palin

Despite the fact that she is a whiny, genuinely stupid quitter, Sarah Palin has been popping up all over the place lately. Most recently she has been spouting off some garbage that Obama wants to set up a “death panel” in the health care bill. In truth, the bill calls for discussing one’s living will (and related concerns) with a doctor, should one choose to do that. This serves to better protect the interests of the patient. Such a measure could have avoided that whole Terri Schiavo fiasco. But, again, Palin is genuinely stupid. She never knows what’s going on. She makes this clear – literally – every single time she publicly speaks. She was especially clear when she said some remarkably stupid things about fruit fly research during the campaign season. I mention all this because of some recent research which relied on fruit flies*, and which can have a direct impact on the health of people.

Scientists have discovered the first gene involved in regulating the optimal length of human sleep, offering a window into a key aspect of slumber, an enigmatic phenomenon that is critical to human physical and mental health.

The article is well worth the read, and will probably give a fuller picture than I’m going to give. It’s all about a gene which has some seemingly minor variations, yet these variations (alleles) can drastically affect the health of the carrier.

The researchers found that mutated versions of the gene can affect the time some people go to bed, wake up, and how well they physically, emotionally, and mentally perform throughout the day. For instance, most people need roughly 8 hours of sleep a night, but one gene variant allows some to get back on 6 hours while not experiencing adverse consequences to their health.

And of course, this research was possible due to the contributions of various mice and fruit flies. When researchers would find a particular variant of this gene, they would ‘tinker’ with the same gene in these test subjects and measure the effects. One finding was that genetically engineered mice would compensate far less for sleep deprivation than would the control mice.

It isn’t clear yet exactly what it is about this gene (DEC2) which triggers the change in sleep need, but it may be that it makes protein transcription weaker, but other explanations are possible until more research is done.

*What genetic research doesn’t rely on fruit flies these days?

Ancestral environments and reverse evolution

There’s been a long debate regarding whether evolution can be reversed or not. The general trend has been that it can not. The idea goes that once one evolutionary pathway has been crossed, it cannot be retraced back to its origins. It turns out that is not entirely true.

Says [researcher] Henrique, ‘In 2001 we showed that evolution is reversible in as far as phenotypes are concerned, but even then, only to a point. Indeed, not all the characteristics evolved back to the ancestral state. Furthermore, some characteristics reverse-evolved rapidly, while others took longer. Reverse evolution seems to stop when the populations of flies achieve adaptation to the ancestral environment, which may not coincide with the ancestral state.

What the researchers did was subject fruit flies to various selection pressure for multiple decades, i.e., they changed their environment over and over. The ‘end’ result was fruit flies that were markedly different in their traits as compared to the original specimens. That’s evolution. Children should understand that. What happened next was the researchers mimicked the original environment of the fruit flies from decades gone by. In response, the fruit flies adapted to those environments, possessing many of the same allele frequencies they originally had. What I find particularly interesting is that they did not evolve exactly the same, but they still evolved in a way that was similar to the original phenotypes. This helps to explain why sharks and horseshoe crabs remain so similar for so long: the gene pool of the population centers around certain allele frequencies because, well, they work. Change may happen – in fact, it certainly does – but ancestral pheno- and genotypes can evolve to such similar future counterparts as to make little difference in show, even though we know there to actually be differences, at least in contigency. It’s a bit like how two people of very different backgrounds and even different alleles can come to have the similar tones to their skin. Their evolutionary contigency, or histories, are different, but the result is virtually the same.

Another point of note here is that evolution can produce similar things, but it will almost never produce the exact same thing. The history of life, if rerun, would be much, much different in all likelihood. When exolife is discovered, we’ll have indirect confirmation of this. Until then, it should be important for people to realize that nothing in biology is inevitable – including humans.

Palin and Science

Sarah Palin is spouting off again on science. She still has no idea what she’s talking about.

You’ve heard about some of these pet projects they really don’t make a whole lot of sense and sometimes these dollars go to projects that have little or nothing to do with the public good. Things like fruit fly research in Paris, France. I kid you not.

Here are some links from the first search page on ScienceDaily.com. Search term “fruit flies”.

In Lean Times, Flies Can’t Survive Without Their Sense Of Smell
For Best Pest Detection, Suit The Attractant To The Fruit Fly
Bar Flies: Fruit Flies Searching For Shut Eye: Possible ‘Sleep Gene’ Identified
The Good And The Bad Of A Potential Alzheimer’s Target
Fruit Flies Learn and Remember Better When Lacking One Receptor
Human Aging Gene Found In Flies
Like Sweets? You’re More Like A Fruit Fly Than You Think
One Missing Gene Leads To Fruitless Mating Rituals

There are another 45 pages of results.

Update: I just found a little more info on this earmark. Numbers range from $211,000 to $826,000 (the reason for the discrepancy is unclear). This link gives the upper range. The point of the research seems to specifically rely upon saving California’s olive groves – not that Sarah Palin had any idea, nor that it would have mattered if this was even some of the research into fruit flies that goes to understanding autism.