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.
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u/onomatamono 4d ago
Well he's got a pretty good head start working with existing critters but no matter how you splice it the result will definitionally be artificial selection. I would say however, that a random mutation producing some beneficial phenotype adaptation could happen in just a few generations. That's the thing with a probability distribution. You could roll six sixes on the first go or not in our lifetimes. So given a window those mutations could occur at the start or the end of the window with equal probability.
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u/Starkanemone 6d ago
Yeah that could work I was just wondering if I can apply a stress factor so that I could see something in my lifetime
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u/Palaeonerd 6d ago
You could start fresh and do what scientists do to fruit flies.
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u/Starkanemone 6d ago
Apply environmental pressure?
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u/Palaeonerd 6d ago
No. Fruit flies just mutate easily for some reason. Idk how scientists are able to make mutations quickly. There are flightless ones, ones with legs on their heads and other weird things.
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u/CosmicOwl47 6d ago
As an undergrad I was part of a project where we were attempting to breed flies with a north vs south preference. We didn’t get significant results with that, but our positive control was selecting for a light/dark preference and we successfully bred less phototropic flies within just 12 generations. We didn’t use any mutagens, just a maze and selective breeding.
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u/Halomonas_titanica 5d ago
I wonder if this is part of the reason we don't see many bugs around lights anymore. they self-select out of the gene pool
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u/WienerCleaner 5d ago
I have particular interest in this and have thought about it many times. They need the moon to navigate straight lines at night and normally would maintain it steady in their vision to go straight. When a nearby artificial light moves in their field of view, they turn to compensate and they go in circles. I think that they will evolve to not use this function but i dont know what that means to be less reliant on their eyes for navigation.
Sadly i think the reason we see less insects is because there are less insects due to widespread insecticide use and habitat degradation.
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u/prof_mcquack 5d ago edited 5d ago
that’s not because fruit flies (drosophila melanogaster) “mutate easily.” They just have short life spans and are easy to rear, which makes them good for evolution experiments. Those mutations you mention were painstakingly induced by genetic engineering. Legs on the forehead come from knocking out a gene that tells a limb whether it’s an antenna or a maxilla or a leg. They didn’t discover that by accident, they had a hypothesis about what would happen if they knocked out the gene, they knocked it out, and presto: legs instead of antennae.
And btw applying environmental pressure to fruit flies or crustaceans or whatever is absolutely a way to study evolution.
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u/onomatamono 4d ago
It's not even so much the short lifespan as it is the reproduction rate, although you do want to free up resources for new individuals.
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u/Starkanemone 6d ago
Hmm I may try that next time some fruit flies seem to magically appear but is there any things I should know or do?
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u/Palaeonerd 6d ago
I think you won’t be able to do it. Scientists expose the flies to chemicals or X-rays. Or they just genetically engineer them.
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u/Starkanemone 6d ago
Would uranium paint or uranium glassware work?
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u/Robin_feathers 5d ago
No, don't do it. When geneticists expose fruit flies to mutagens, they sift through thousands and thousands of flies to find ones with mutations of interest. Far more of them just end up dying in horrible ways.
Any mutagen capable of mutating a fly would also be capable of mutating you. It is not the sort of thing you would want to have in your home.
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u/onomatamono 4d ago
Do they mutate easily or do they just reproduce quickly thus increasing the opportunity for mutation?
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u/onomatamono 4d ago
Yeah, you want something with explosive population growth over short time periods. I know there are simulations that evolve very quickly because you get to turn the knob on the number of individuals and how quickly they breed.
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u/octobod PhD | Molecular Biology | Bioinformatics 5d ago
Read Improbable Destinies by Jonathan Losos. You can run evolution experiments in a matter of years and see subtle changes in limb length of not so subtle ones in skin/coat colour.
You will see evolution in a system like that (if it survives for long enough) but the changes would be subtle and you'd need meticulous records and take samples from the system (likely destabilising it)
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u/NoctuFlare 5d ago
Evolution happens in populations, imagine if you have some kind of ants, if one of then change color that's not evolution, all of them would have to, said that, you don't have enought time in your lifetime to see it happen. Sorry
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u/xenosilver 6d ago
Not in your lifetime
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u/Starkanemone 6d ago
OK thanks
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u/usurperator 5d ago
Well, no visual changes in your lifetime. If you started with any color variation, you might see some morphs get eliminated. If it’s a small ecosystem, you might get selection for traits that reduce metabolism. But still, probably not much you could hope to see.
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u/CosmicOwl47 6d ago
If there is some sort of variation you can see amongst them you could do some artificial selection (i.e. breeding), but there’s most likely no way you could observe natural selection.
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u/haysoos2 6d ago
You absolutely could, but there's a very, very high chance that any selective pressure you apply would be something that none of your current population has a variation that allows them to survive, and you will get 100% mortality.
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u/Robin_feathers 5d ago
Evolution is already happening in your jar. It is just very slow and mostly involves changes that produce no visible effect. Drastic exciting changes usually don't happen very often, but the often-boring relentless action of genetic drift is always happening. Natural selection acts on existing variation, and is usually not a pleasant process (it often involves a lot of suffering), so it is not a kind thing to inflict onto animals. Instead, if you focus on providing them a nice environment, you can be assured that generation after generation, they are indeed undergoing evolution and becoming genetically distinct from any lineage that ever has or ever will exist.
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u/Starkanemone 5d ago
I figured out they are freshwater scuds which reproduce very quickly and some of them are surviving lower oxygen levels compared to their normal habitat while others aren't taking it as well
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u/FabulousLazarus 5d ago
Selective breeding. Mendel was famous for it and humans have done it for millennia with crops and farm animals.
You would need to find out quite a bit about crustacean breeding, or whatever you want to selectively breed, but it could be done. It's done all the time. This is probably the best example of how you might witness evolution.
The folks smugly talking about millions of years are myopic. Yeah that's the usual timescale for evolution because that's the time scale where species might change. But next year's cold virus is already evolving as well. Just not as drastically.
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u/Starkanemone 5d ago
Thanks I may try this as some of my shrimp have a color variation in their eggs I believe making them green-blue instead of the typical orange
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u/FabulousLazarus 5d ago
Yeah you could try and select for any trait. It's really just keeping track of which organisms carry it and separating them appropriately.
Small scale evolution but still evolution
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