Eventually, in a culture of a billion cells, a few have become resistant. Expose the culture to antibiotics, and the resistant cells survive, and eventually take over the culture.
They do not ‘become’ resistant, they ‘are’ resistant regardless if you expose them to antibiotics or not – and if this resistance was not present they would all obviously die once exposed regardless if mutagens were present. To say otherwise is adding a purpose, direction, or plan to evolution. Naturally speaking; nothing becomes ‘resistant’, or is ‘beneficial’, or ‘selects’ anything. It is - or isn’t --- regardless of the situation. There is no ‘choice’ in this matter and basically natural selection boils down to survival and reproduction – that’s it…
(soapbox mode)Honestly, in a naturalistic evolutionary view – life is nothing more than fire in the way it feeds and continues in this fortuitous world it happened upon. It is basically a chemical reaction that started, grew, feeds on the current environment, changes with the wind, and will ultimately burn out. (/soapbox mode)
I notice that since your original claim -- that the only reason for antibiotic resistance in a population is their existence from the beginning -- has been soundly refuted, you're going off on a complete and total tangent, addressing claims that no one made.
How many ways can you spin the obvious? One bacterium starts as nonresistant, it is allowed to breed and mutate, some in later generations become resistant, which part do you not understand?
That is false. They are all descended from a single cell. In the absence of mutation, they are all either resistant or non resistant. If the original cell was non-reistant, and a descendent is resistant, then the descendant became resistant.
I'm unable to figure out what your difficulty is here. Do you want to parse the word 'became'? Or do you deny the truth of how I've described the experiment?
Naturally speaking; nothing becomes ‘resistant’, or is ‘beneficial’, or ‘selects’ anything.
When a salt crystallizes from water, it becomes crystalline. There is no implication of purposefulness in the ordinary meaning of the word 'becoming'.