Having publicized the existence of my in-browser software I’m beginning to get questions. One of the more frequent ones is “What do I do in/with 100 Places?” 100 Places is designed to teach about niches and niche partitioning in ecology. It’s also designed to simplify this a lot so the only way to make organisms different is by choosing how they allocate their energy. All organisms use the same resource (space) and get the same amount of energy per turn (100). Only the allocation of energy (and some human-friendly things like names and colors) can differ between species. So here are some basic things you can do with it:
- Demonstrate competitive exclusion. This is simple. I’m going to make four identical species, differing only in color and name. Since I want this to go quickly I’ll up their ability to survive in harsh squares (allowing them to populate the whole board lets runaway ecological dominance runaway properly) and steal that energy from their ability to resist herbivores and disruptive events. See below, complete with totally awesome species names1.So what happens when we start the simulation running? Well, the board almost immediately fills. However, WeaselBait loses out in the mad scramble, and ends up with less individuals than the others.The graph is extremely choppy at this point, since nothing has any resistance to the herbivores wandering through and the disruptive events (let’s call them storms) and so large open patches are constantly appearing and then being filled. But by the mid-200 turns Kataklysm has (somewhat ironically) lucked out and has a commanding population lead. Somewhere around turn 600 Harmaggeddon shuffles off this mortal coil. At this point Kataklysm has a population of 79 (remember, 100 is the maximum population of everything put together) and so any open spot immediately gets spammed by Kataklysm seeds. By turn 750 PoofyPants is gone, too, and only Katakylsm and WeaselBait (which, ironically, looked worst-off at the beginning) are left. Around turn 900 it’s all over – nothing is left but Kataklysm, which is presumably high-fiving its teammates and yelling, “COMPETITIVELY EXCLUDED!” at the other species.
This example is a particular sort of competitive exclusion in that the winner is random because all species are identical. However, it demonstrates the idea very clearly. Even though all the species function exactly the same and so there is no “best” species2 there is still only one survivor.
Obviously, one other thing you could do with this is play with the environment and organisms to see under what conditions/what kind of organisms does the resolution of the scenario (i.e., the extinction of three species) take longer. Does apparent coexistence last longer in some scenarios? Probably. I have a suspicion that I should have turned down the rate of disruptions to make things resolve quicker in my example.
- Can you make an organism that can push the generalist that is auto-created at the beginning of the simulator into extinction every time? This is also competitive exclusion but of a different sort since here there is a “best” species. This should also be easy since the generalist is literally just allocating the same amount of energy to every task. Some tasks are probably not worth that energy and so it shouldn’t be hard to design an organism that takes energy from these tasks and puts it somewhere more useful.
- 100 Places is named 100 Places because there are only 100 Places and places are the only resource the simulated organisms (I think of them as plants) need. How many species can you get into stable coexistence in just 100 places?
- Habitat variation should make it easier for more species to exist stably. The default habitat has a harshness range of 0-50. If you up the range to 0-100 can you cram in a few extra species and keep it stable? If you drop the range to 0-20 can you still get a bunch of species to coexists? What’s the effect of absolute harshness, anyway? Is 0-50 a whole different ball game than 50-1003?
- What is the effect of herbivores and disruption? They are very similar as game mechanics (although herbivores are constant and hit one square at a time while disruptions are random and hit multiple squares) but since organisms have to allocate energy to deal with them separately you can have organisms resistant to one but not the other. In theory (Intermediate Disturbance Hypothesis) you should be able to balance out a slow-reproducing, highly competitive species with a fast-reproducing, non-competitive species if herbivores/disruptions kill of individuals of the competitive species at the right frequency. Too much disruption and you lose all the slow-reproducing species and too little and the competitive species squeezes the non-competitive species out of existence.
During all of this you will also see some rather classic ecological growth curves.