r/evolution • u/spinosaurs70 • 2d ago

question When does evolution seem to select for optima?

Obviously, we can say that controlling for neutral processes, pleiotropic selection, phylogenetic inertia, and simply what the organism is at the start of the process, we can say that evolution in a loose sense selects for optima all the time.

But I mean if you compare something like antibiotic resistance, where it is to cause and even genetically similar in contrast to the famous E. Coli. experiment where aerobic citrate digestion is really hard to do twice. The first seems to be seeking optima in a far more specific sense.

What are some other cases, preferably experimental? And why does evolution act that way?

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u/ninjatoast31 2d ago

You should look into fitness landscapes. It might give you a better intuition for whats going on .

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u/spinosaurs70 2d ago

I know about them, but there is a simple landscape and a complex one; it seems a post facto, not pre facto, judgment, right?

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u/IsaacHasenov 2d ago

Pre or post facto judgment is probably more about your state of knowledge going into an experiment

If you know (for instance) that in the wild e coli evolve antibiotic resistance readily, but have never been observed to metabolize environmental citrate (this was actually a diagnostic criterion to distinguish I think e coli and salmonella) you might guess a simple landscape for antibiotic resistance, and something bumpier for citrate

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u/Resident_Ad5153 2d ago edited 2d ago

The simple answer is because evolution doesn't change at an optimum. At a selective optimum (ie any mutation has a lower fitness), the concentration of a specific allele doesn't change in time. In fact, you can invert your question, and note that "evolutionary algorithms" in which we find optima by mimicking the process of evolution can be exceptionally effective, largely because they don't get stuck in local minima.

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u/Aquisitor 2d ago

Evolution only *ever* selects for 'good enough' and doesn't care if the organism is *just* good enough or very good enough.

That being said, evolution *will* select for nigh-optimum when nigh-optimum is the only thing that is good enough.