(September 13, 2016 at 10:03 pm)Tiberius Wrote:(September 13, 2016 at 5:28 pm)RoadRunner79 Wrote: Perhaps it would be more apparent in real time, but I didn't see them stop much at all.
Watch the video again from 0:49 until 0:53. Remember, this is a timelapse across 11 days, so 4 seconds in the video is several hours in real life. The bacteria were reproducing quickly before and after that point in the video. There's a clear moment (when they reach the antibiotic) when they just don't reproduce in that direction, until a mutation occurs (at 0:53).
I was watching compared to the normal rate of expansion.... I still think that this could be explained as a bottleneck, and that some bacteria where at least partially resistant before... more study would be required.
Quote:What I seen could possibly be explained as a bottleneck, where most of the bacteria where not able to survive in the antibiotic, but some where. Once they got through, then they where able to spread in the new medium and start reproduction again.
I think you're missing the point. The bacteria are all the same species at the beginning (the same strain) and none of the original strain were able to survive in the antibiotic. Bacteria reproduce by splitting themselves in half, making an almost identical copy of themselves, so unless these resistant bacteria were introduced externally somehow (which is certainly a possibility that I suspect they looked into / controlled for), they must have come from the original strain after several generations.
If the original strain was not resistant to the antibiotic, and some of the strain's descendants are, that means they evolved the ability to resist the antibiotic at some stage, through a mutation.
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I understand that they are all the same species (a form of E. Coli) I believe. My point was to minimize the initial genetic diversification within the starting group. Bacteria are highly adaptable, and the changes are more pronounced under stress. I'm not saying that it definitely isn't evolution (change over time). But I think that there are other possibilities.
While I would like more trials, I did re-watch the video; and there are two samples here on either side. If you watch, while the left side falls behind a little, and there is a definitive spot in the middle which struggles near the end, they for the most part keep up with each other. I would predict, that this would be repeatable, as to the point I made previously.
