Time for an overdue update:
Today I overhauled the way reproduction worked.
Previously I was doing reproduction exactly the same way Nick was: Every microbe has an arbitrary reproduction factor. For every full timestep spent reproducing they create a number of new microbes equal to the reproduction factor (set to one in the previous updates). This has two unrealistic consequences I’d like to fix:
- Reproduction takes equally long for every species. This means that giant eukaryotes are taking just as much time to reproduce as tiny P. Thrivium (who breed like rabbits in the real game).
- Food supply is the only limit to how many microbes can exist. This means that autotrophs could keep exponentially growing their population forever, filling the entire patch several times over.
In the simulation, I made microbes gather and compete for clouds of ammonia and phosphate just as they do for food. The amount they need to collect to create one new microbe is based on the composition of their organelles, taken from the source code of the real game. There, I noticed to my HORROR that metabolosomes and thylakoids both cost LESS than cytoplasm. I resisted the urge to correct this because it doesn’t make sense, and will adjust my speedrun strategy in the future.
Anyway, this fixes both issues:
- Now reproduction takes longer depending on the cost of your organelles, and how fast you are at gathering compounds. P. Thrivium has an edge over giant eukaryotes in both departments.
- Because there is only so much ammonia and phosphate in a patch, there can only exist so many microbes at once. Once all the compounds in the patch are used up, that’s it. Naturally, if a microbe dies, he deposits his compounds back into the patch. Otherwise patches would run a net loss and die out over time.
Here are some example scenarios:
A cyanobacterium (1 thylakoid, cell wall membrane) is alone in a patch, what will happen now that he has to work with limited resources like this?
It still grows (almost) exponentially at first, but the graph levels off once ammonia and phosphate run out.
For our next experiment let’s see what happens when we make P. Thrivium compete against Ammoniae Aedifex (one metabolosome and one nitrogen fixing plastid). A. Aedifex will be able to make ammonia out of thin air, but constantly spend ATP doing so:
Unfortunately A. Aedifex was not able to keep up with the ATP costs and quickly starved to death. A look into the internal variables reveals that they were not able to collect glucose fast enough to keep up with their ATP demand once it got below a certain density. Once they go extinct P. Thrivium briefly peaks due to its new lack of competition, and then falls into its equilibrium population.
For the final experiment I want to test how much better metabolosomes really are than cytoplasm. So I pit P. Thrivium against P. Metabolosomus (one metabolosome):
ngl I was completely taken aback by this. P. Thrivium actually held his own! This is the first time in all my testing that a species was able to survive in the face of superior competition. Not only that, but he never actually reaches a stable equilibrium, instead bouncing back and forth between two populations. I suspect that this is a fluke of how various numbers are discretised (like the number of clouds, number of microbes, etc.) and that the population would simply reach 72 in a continuous model. But who knows, irl sometimes shit like this happens too.
I am beginning to suspect that the patch I’ve created might be a bit too harsh, if even super-optimised species like P. Thrivium and P. Metabolosomus are barely clinging on with less population than they started with. That’s why I’ll see you next update when I’ll be recreating some of the patches that are actually in the game.
Until then hmu if there’s some scenario you’d be interested in seeing.