Human Evolution-Bacteria Conjugation

[PhysicsFan11]

I don't see any indication that it would have occurred very early or very late. Estimating the probability precisely looks like a huge challenge.

So, with regards to the E.coli evolution experiment, would modifying the culture medium of the E.coli change it from, as noted earlier, a purifying selection process to a diversifying one? If the E.coli were placed in a more natural environment with amplified survival pressure, could we expect diversification of E.coli phenotypes?

 

[mfb]

That is possible.

 

[PhysicsFan11]

It would be remarkable to see if this diversification (over many generations) led to something similar already seen in nature, or if entirely new phenotypes came about.
It would conversely, be quite consequential if the diversification process (in this setting) fell flat and not much came from it, beyond prior observations.

 

[PhysicsFan11]

So the different kinds of environments could be: varied temperatures, light/dark exposure, pH variances, tepid versus turbulent environments (that which would simulate wave action, for example) and variations in nutrients and base chemistries. This would mimic conditions found in nature.

 

[Drakkith]

So the different kinds of environments could be: varied temperatures, light/dark exposure, pH variances, tepid versus turbulent environments (that which would simulate wave action, for example) and variations in nutrients and base chemistries. This would mimic conditions found in nature.

There have been a great many such experiments. One of the first was William Dallinger's experiment from 1880-1886 in which he gradually increased the temperature of samples of bacteria from 60 F to 158 F. The initial population of bacteria couldn't survive at a temperature anywhere near 158 F. Conversely, the population that could survive at 158 F could no longer survive at the original 60 F temperature.

A huge number of similar experiments have been performed since then that do exactly what you're asking about. Here's a PHD thesis from Alex Hall on the subject: https://www.era.lib.ed.ac.uk/handle/1842/3977