[ExI] 5th Grade Science Fair -- Evolution

Kelly Anderson kellycoinguy at gmail.com
Sun Mar 25 23:17:29 UTC 2012

2012/3/25 Giovanni Santostasi <gsantostasi at gmail.com>:
> Do you buy the flies from a biological supplier?

I bought them online, the Commercial Size... You could buy a smaller
kit, but I wanted enough stuff to go multiple generations.

> Which one? Would be interesting to see a graph of average speed as a
> function of generation number.

That's what we're hoping for. We have a little graph now, but it's not
terribly interesting so far. Also, it seems that they are getting
larger, so I'm looking for a sensitive scale to weigh them.

> How many generations you got so far?

We have the Control, a First Generation Selected and a Second Generation.
If control speed is 1
First generation speed is around 1.4
Second generation speed is around 3.7

> Could
> you get the speed of individual flies (if not all, at least a good sample?).

What we did was take a video, then cut the video off in a video editor
at the starting point, then took frame shots at 4 seconds, 8 seconds
and 12 seconds. Then we counted how many flies were in various
sections of the cup (sometimes we had to refer back to the video to
see what was going on in the still frames) and then figured the
average length they would have to go to get to that part of the cup,
and the rest was just simple math.

> It would be interesting to see the distribution of the individual flies
> speeds to see if there is a change in distribution.

The fastest flies are a bit faster, but the majority of the difference
seems to be that there are fewer flies content to sit on their butt at
the bottom of the cup.

> Another thing to be
> careful about is when you take the speeds, try to do it at the same time of
> the day and under same light conditions, because circadian rhythms could
> affect the speed.

We race two cups at the same time and video them both side by side.
That way, for any given race, we know how much faster the group we are
measuring is compared to the control.

> That could be an interesting follow up of your study
> (maybe for next year project). How the flies in each generation change their
> rhythms, do they become more synchronized with the from biological rhythms?
> Make sure to keep similar light-dark cycles conditions during the
> experiment.

The thing that I'm curious about is whether the improvement will peak
out at some point... whether there is a point beyond which they simply
will not improve any more. And of course, it would be super cool if we
actually got a new species... but I'm not counting on that... :-)
Might take hundreds of generations to do something like that, but it's
going faster than I thought so far, so we'll see.


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