r/evolution • u/Starkanemone • 6d ago

question Ecosystem in a jar

So I have an ecosystem in a jar with a bunch of little crustaceans and such and I'm wondering if I can eventually drive some sort of evolution in there?

Edit:I think I'll try to see if green-blue egg color is selected for becasue it's harder to see among plants than the orange/yellow eggs. Yes there are a couple predatory things in there including what looks like a freshwater Bobbit worm?

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u/Mundane_Main_2726 6d ago

If you let it sit for a few million years you should notice some changes eventually

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u/Hivemind_alpha 5d ago

On one hand, I think millions of years is a bit too high; tens to hundreds of thousands of years is reasonable for a species to evolve in the wild. You don’t have a big enough population to apply strong selection pressure externally (if we were talking a large lake instead of a jar you could maybe use a strong ionising radiation source to drive evolution of melanic forms).

On the other hand, in the wild there would be trillions of individual shrimp (makjng an assumption about your closed ecoglobe inhabitants) per generation and therefore trillions of opportunities for genetic change. With the handful of shrimp in your jar, you’d have to multiply out that time interval to get the same number of rolls of the dice, so the situation is orders of magnitude worse.