Niches

I decided to make this thread as a place to discuss the Niche System that will either have to be implemented in Thrive or coerced to occur naturally. This is a phenomenon that will effect most of the game, especially AI and Auto-Evo. I feel this warrants it’s own topic simply because of how important it is as a biological and possibly game concept in it’s own right.

What is a Niche?

In real life, a niche is essentially the “job” a living thing plays in it’s ecosystem. This “job” is determined by countless biological and even abiotic factors that are quite frankly impossible for me to list however, lucky for us it can be abstracted quite far in terms of the effect we’re after. In nature, just about everything can be placed in only a few fundamental niches.

Fundamental Niches

In the absolute simplest terms, niches can be defined by how energy is obtained. This gives use roughly 4 base classes.

  • Producers
  • Primary Consumers
  • Secondary Consumers
  • Tertiary Consumers

Each of these can also be subdivided into even further sub-niches but these cover every living thing as it is. I will describe each of the 4 niches and try my best to link them with the game as we know it.

Producers

Producers are those who create energy and store it. In our game this would reflect as those who primarily dedicate their existence to collecting a raw resource and converting it to Glucose.

This is the niche of Plants and Phytoplankton.

Primary Consumers

Primary Consumers are those who to collect energy by simply harvesting it from producers, avoiding the need to dedicate to the production of Glucose. However, those in this niche must spend a significant amount of time grazing to acquire sufficient Glucose.

This is the niche of Herbivores, Zooplankton, and Parasitic Plants.

Secondary Consumers

Secondary Consumers will collect energy by taking it from Primary Consumers. This seems redundant but it means, an organism can make huge resource/energy gains in very short periods of time.

This is the niche of Predators, Parasites, Ovivores (Egg Thieves), Planktivores (think whales and other such filter feeders), and Opportunist (like mice who will eat both vegetation and bugs)

Tertiary Consumers

Tertiary Consumers are the final consumers in an ecosystem. These are those who act as the ‘final’ passing of energy. They are either insanely hard to kill or only eat that which has rotted or can only be seen as waste product to lower niches.

This is the niche of Apexes, Scavengers, and Decomposers (think mushrooms and certain bacteria).

Connecting the Dots

What does this all mean for Thrive? One phenomenon of life is a tendency to fill every niche. Niches that are already filled will also see competition should interest and methods be too similar, this is why we see variety. Whether by pure mathematical chance/design in the algorithm or an intended explicit function that guides auto-evo and AI behavior to fill base Niches in a particular biome/patch, we must ensure the game reflects this phenomenon or the game will always feel sluggish and the AI lazy.

please feel free to discuss

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I think this is a good start, but I think things may end up being too restrictive if we stick everything into one of these four trophic levels. For one, what if something evolves to prey upon a tertiary consumer, becoming a quaternary consumer? Or possibly even higher? Furthermore, where would decomposers and detritivores fit in this?
Also, trophic levels aren’t always clear cut. Consumers may consume species on multiple different trophic levels, plus some extreme examples exist, like some plants being consumers themselves

It might be more flexible to define niches in terms of not only what energy sources they use, but also how much they rely on them, and where and when they get them. With this extra information, two species could coexist in the same ecosystem, despite getting their energy from the same place(s), by differentiating their niches in some way, like so:
image
The diurnal and nocturnal predators can coexist because they’re technically occupying different niches.
Niches can also be differentiated by hunting in different locations, though the usefulness of this in Thrive is debatable because patches are basically homogeneous throughout, though some may still have some variation (higher vs. lower on a mountain for instance?) and some organisms (think trees) can add some terrain of their own, but that’s definitely too complicated for now.

side note. about day/night cycles

In order for this to be implemented, cycles of activity must also be implemented. A “nocturnal predator” niche can’t be filled by a species that sleeps at night. Also, hunting of a species itself must also take note of the prey’s behavior at different times; a nocturnal predator’s strategies will be much different from a diurnal one if its prey sleeps at night, being focused more on very perceptive night vision, stealth, and ambushing. Also calculating this if a predator’s hunting time overlaps times where its prey is both awake and asleep will be quite difficult…and also, yes, sleep would also need to be implemented. And think about how complex these “calendars” would become with an especially exotic orbit arrangement with tons of eclipses leading to an unusual pattern of irregular day lengths.
I’m getting ahead of myself now, but I think it’s important to consider these things, either so we have a better idea of how to implement them in the future, or so we can decide whether or not it’s within our game’s scope at all.

This strategy (niches based on energy source) might be harder to get correct right away – there’s no guarantee your apex predators won’t still try to eat plankton, for example – but overall it will allow for more flexibility.

This categorization of consumers (Getz categorization) may also prove useful/interesting. These aren’t necessarily names or labels we have to adopt, but it gives a good picture of the variety of different consumer niches:

[it] organizes resources into five components: live and dead animal, live and dead plant, and particulate (i.e. broken down plant and animal) matter. It also distinguishes between consumers that gather their resources by moving across landscapes from those that mine their resources by becoming sessile once they have located a stock of resources large enough for them to feed on during completion of a full life history stage.

Another concern I have is that competition might be too easy to fall into. In real life, every time multiple species eat the same food source and happen to be awake at the same time it isn’t immediately a fight to extinction, but I have to admit I don’t know enough about those situations to know why that is exactly.

Furthermore, on a producer level, there might not be enough variety in energy sources represented in-game to support more than one single “plant” niche per patch, so whichever species is best at photosynthesizing and using up the nutrients from the soil gets all the sun to itself. The paradox of the plankton seems to be relevant to this problem.

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If something evolves to prey upon a Tertiary Consumer, that thing would become a Tertiary Consumer and the thing it preys upon would either become a Secondary Consumer if formerly an apex predator as it is no longer Apex and the chain has extended, or they would both be Tertiary Consumers. Decomposers are the majority of the Tertiary Consumers.

I mentioned this. Niches can be subdivided into smaller niches down to individual species/families of animal, and things within a niche can consume each other, some can even switch niches just by having the wrong personality or behavior (like with herbivores eating meat out of desperation and still digesting it while risking disease). The point of the big 4 is to identify the Macro Niches that we will need absolutely everywhere. You can think of them as Base Classes to assign the most basic hierarchy logic. From there, we can always add more nuance since we’ll have a solid base.

i’m not sure i follow this logic, but it’s super late so i’ll be going to bed after this.
how does a predator preying on a tertiary consumer change that species’ trophic level and make it secondary? You don’t start preying upon a (former) apex predator and see it suddenly start only eating herbivores. the chain has been extended, not squished down.
And, in the other scenario, how would this predator also be a tertiary consumer if it’s one extra step up from the tertiary consumer it preys upon in the food web?

Perhaps you’re right about this being a more solid base than I imagined, but i still think having a limit of 4 base trophic levels, at which apex predators are defined to only be on the fourth, is not the best idea.

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I think hard coding niches is a bad idea given the wide range of possible energy sources creatures can rely on, for example, where is a iron chemolithoautotrophy on that, i feel like defining ecosystems via hard coding will limit us significantly. Perhaps some kind of niche partitioning algorithm that dynamically adds and removes trophic levels would be better. It would also mak ethings less earth centric, for example, where is a predatory plant, on it.

The Trophic Levels would be generated according to energy available in accordance with the 10% law, and the Niches would be generated according to those Trophic Levels but it’s unlikely to vary much if our game assumes the Sun being the primary source of energy given the narrow conditions needed so life isn’t either nuked by the sun or frozen by the cold of space (though, again what’s important is energy so it can probably come from other places). I’m trying to make a model to show off how this would all work on a patch given X amount of energy and better explain.

The game does not assume the sun is the primary energy source, in fact in the vents the primary energy source is hydrogen sulfide. This will also be the case for frozen moons (which are part of our plan) They will rely on thermoplasts heat generated from the planet squishing the moon as it orbitsand sulfide and such, not light.

There are ecosystems on earth that don’t rely on the sun, for example in hydrothermal vents. And underwater caves (primarily hydrogen sulfide in that case)

Deep sea ecology: hydrothermal vents and cold seeps | WWF?

This means that the niche system needs to be generic enough to work in the case of hyfrothermal vents and other more wild ecologies.

It would be that generic, the only thing that matters for what I propose is energy. But like I said, if we don’t make things other than the Sun very viable throughout the game, then the result will always be more or less the same given the nature of the Sun.

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In fact even now in the microbe stage, we need to support niche partitioning in the case of sunlight, hydrogen sulfide and iron chemolithoautotrophy as primary energy sources (admittedly we made iron auto-litho-trophy more powerful than real life) But you get the point

Good, im just making sure this is brought up right away :slight_smile:

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In the case of iron its more bizarre though, they are autotrophs that have to seek out their food. SO it needs to support that weirdness and detect similar weirdness. (not that a colony of litho-autotrophic prokaryotes cant live on top of iron particles and be stationary in that way, so maybe its not an issue)

But even with sunlight, we get carnivorous plants in real life, so it cant be too harsh, we should be able to get plants that are a bit less of a producer and more of a consumer. But can still hold that producer niche.

Edit:
Also, as @Narotiza brought up, it is always more then the base 4 trophic levels of niches, you can have two consumers, one in the trees, and one on the ground and they will be the same trophic levels, but their niche prohibits competition (one is in the tree one isn’t so they do NOT compete) that’s the whole concept of niche partitioning that is why it happens, is so creatures don’t have to compete, this partitioning can be so extreme that all it is is a different beak shape for drinking nector from a differnet flower, it is so atomized and those two species dont compete. And so i think Naros suggestion of adding new niches that are “attached” to the different trophic levels is a more cohesive and effective way.Niche differentiation - Wikipedia But tahts just my opinion.

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What you’re referring to is still compatible with there only being 4 Trophic Levels (like in real life). This is because Trophic Level can be fractional. Humans are a solid example because we eat things quite regularly from different levels, so our Trophic Level is something of an average. I’ll explain what I’m thinking of better soon, I’m going to be dropping a big post here soon.

Also, I specifically stated earlier that a Trophic Level could have different sub-niches.

I think it’s important that niches be tied as closely as possible to energy sources and other organisms that exist in the ecosystem, so the player understands their niche as something closely intertwined with the ecosystem, rather than a box that’s open for them. If niches are generated just according to energy input and patch characteristics, it doesn’t seem to actually be rooted to anything, and might even suddenly disappear because patch conditions worsen.
This is all based on my understanding of what you’ve been suggesting, but it’s possible I’ve misunderstood (or my understanding is incomplete compared to what’s in your head right now) so I’ll be awaiting your Big Post
Can you elaborate on what these sub-niches would specifically entail? What’s their relation to other niches?

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If energy is contained in organisms, than that would be a modifier that says a niche must be able to interact successfully with said container to obtain energy (so kill it and eat it).

Sub-niche is if we decide we need more specific niches beyond just Trophic Level. Right now the auto-evo just makes things on seemingly pure RNG and 90% of the time the designs are unfocused and plain bad (especially compared to the player). Trophic level would at least set up very basic forms of Niches and a pattern of predation. Sub-Niches are where Patch Modifiers get involved. Patch Modifiers are any pre-existing condition that effects how many Niches there are, and what can be a member of a Niche. So for example,

Altitude – It is sensible that members of the first Trophic Level would vary in size, meaning light would be available in different amounts at different altitudes as taller members block it. We may simplify and implement something that splits Niches for small, medium, and tall members. So, we now have 3 Niches so far. Each Niche would also have requirements of different levels of shade tolerance as light would be less available the shorter a member is (due to larger/taller members blocking light).

Because of various confusions around my explanation I have decide to make a model demonstrating how Niches would work, and how they might be generated.

Before we get into the model I should clarify how Trophic Levels work better and why there’s generally about 4 (decomposers are usually set to the side or classed with whichever is final) and how I envision Niches being handled to some extent.

In nature, there is something that occurs known as the 10% Law. In essence, at each level only 10% of energy can be passed on. The following image demonstrates:
image

Using this law, we can establish the most basic information and hierarchy we need to help define our Niches (In particular, we can class prey and predator AI). So, a niche in the 2nd Trophic Level would primarily list prey in the 1st Trophic Level, a niche in the 3rd Trophic Level might list items in the 2nd, and so forth. It’s also possible for a Niche’s Trophic Level to be fractional, or something of an average, so one could have prey in various levels which is realistic as most Tertiary Consumers don’t spend all their effort on difficult prey like lesser predators and often eat other things too.

As mentioned before, generally speaking there are only about 4 Trophic Levels due to the Sun. Only so much energy can be gained from it and this limits the depth of such hierarchies. It could be made possible to have more energy available in Thrive to extend how many levels are possible but, assuming the Sun is the most viable, the results will generally be similar every time as there is a narrow range of energy life can withstand from the Sun.

Another key piece of information we get from this is a rough idea of biomass and maybe to some extent diversity. If there is only so much energy available in each level, then it makes sense only so many organisms can exist, and they can only take advantage of so many methods especially as energy becomes more and more difficult to obtain.

I made this chart to illustrate how perhaps, Niches could be constrained by energy available. You could use the energy available to cap not only how many Niches are possible but, how much energy they are able to take advantage of. In the chart I assume 1 unit of energy is required for a Niche to be viable but, this could be tweaked of course.
image

One thing you might notice in my chart is the mention of “Patch Modifiers”. A Patch Modifier is a factor that effects the Niche Count, and how diverse they may have to be. For example, there could be a modifier for Location. It is perfectly possible that energy is not distributed evenly across a Patch, this means there would have to be different Niches for places that are significantly different within the patch or a Niche would have to be able to overcome these differences. There’s also the fact, a place might not be easily reachable from another, which again may mean different Niches. A good example of this could be the difference between a Cave in the patch, and an open area. Another obvious situation is Altitude. If there is energy available higher up, it makes sense there would be Niches to take advantage of greater heights (or able to dig if there is energy down below).

Now for the actual model.

For this model I will be using a fairly basic patch, it is entirely flat land to make things easy and to demonstrate how things may work. There is 5000 units of energy available from the Sun.
image

So, now going through the Trophic Levels we see there are 4 Levels assuming the sun is the only energy source in this patch. The 4 Levels are:

Trophic Level 1 – Producing 500 units of energy

Trophic Level 2 – Producing 50 units of energy

Trophic Level 3 – Producing 5 units of energy

Trophic Level 4 – Producing .5 units of energy (so we’ll say not enough for a new level)

We also have Decomposers; they will act to remove whatever surplus there is left and will produce certain necessary compounds.

Now that we have our levels, which already act as very broad niches themselves, we must configure the sub-niches they contain. We do this through Patch Modifiers. Some basic Modifiers we can use for this example are as follows:

*Day/Night – When is energy available? When is there light?
*Location – Where along X & Y is there energy?
*Altitude – Where along Z is there energy?
*Nutrients – Where is there Nutrients (so stuff like compounds) and in what quantities?
*Containers – Is energy being contained?

And you could potentially keep making more of these as you need to describe different conditions like temperature, how much light there is, etc.

Having these modifiers, let’s model our first Trophic Level.

Trophic Level 1

Day/Night – This modifier would not do an exceptional deal for the first Trophic Level as they can only use light in this situation to produce energy, not the darkness of night. However, this could add a conditional to our current single Niche that members must be able to survive X hours without light (night).

Location – Currently, light evenly distributes across the patch, this modifier would do nothing for now.

Altitude – It is sensible that members of the first Trophic Level would vary in size. We may implement something that splits Niches for small, medium, and tall members. So, we now have 3 Niches so far. Each Niche would also have requirements of different levels of shade tolerance as light would be less available the shorter a member is (due to larger/taller members blocking light).

Nutrients – We could assume the soil is not perfectly the same everywhere in this particular patch. Therefore, we would split up Niches further between those who can cope with varying kinds of soil. We will do another 3-way split to represent poor, decent, and rich soil on each Niche. This gives us 9 Niches.

Containers – This one is interesting. For Trophic Level 1 energy is quite easily available by simply using Photosynthesis however that also means other members effectively contain some energy that may be usable. Taking advantage of this won’t necessarily make them Trophic Level 2 however, as they could still primarily rely on the Sun and only use other members as a supplementary energy source. We will do a 2-way split for members who take energy that is being contained and those who simply focus on photosynthesis. This gives us 18 potential Niches to fill.

Total number of open Niches: 18 splitting up 5000 units of energy. These Niches have a lot of energy between them so it is possible as the game goes on they could split even more, or we could make even more detailed modifiers (for example, there would of course be modifiers that take further into account who is already populating the patch)

Here is my depiction of a patch with 18 different Niches based on the earlier qualities:
image

This is Part 1 and I will continue tomorrow but, please share your thoughts or confusions to me.

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I think I understand the concept a bit better now, though I do have some comments, which I’ll go over here.

I mentioned in this in the Discord already, but I always thought patches were intended to mostly be uniform throughout, definitely not varied enough to contain a cave, nor places like rivers or ponds, whose features are totally different; all of those would probably have to be their own patches, connected to our first one.

However, I suppose that’s not to say patches wouldn’t have some variation within them – it’d be impossible not to. For instance, the bathypelagic patches cover about 3 kilometers of water, and while sunlight wouldn’t vary at all (you get none), pressure would be massively different depending on how deep you are.
Furthermore, a mountainous patch would have terrain of varying steepness and altitude, leading to different requirements of sure-footedness, cold resistance, and tolerance of lower oxygen levels. With fully homogeneous patches, best we could do is “terrace” the mountains, creating individual patches for each piece of the terrain within a certain altitude, which would lead to… a lot of patches.
image
While things like rivers and caves would be too different to consider part of something like a “forest” patch, I think subtle variation in patches is an idea we could embrace, as it could support new niches. And any divisions between what you would’ve considered one patch could be crossed by considering migration (somehow) in our models.

I’m not sure I like this. 3 is a pretty arbitrary number (and would also lead to pretty samey-looking ecosystems, like the three size categories of Plants in Spore). Giving different height niches for just the primary producers feels like us pushing our earth-centric, land-centric viewpoints onto our virtual ecosystems. What about aquatic environments? Do we adopt a different set of rules? In an early patch uncolonized by “plant” life, there will be very little incentive to grow tall, except to perhaps peek over rolls in the terrain that might overshadow you. It is competition between “plants” that would be the main force driving them to reach higher and higher in an arms race of tallness.

If “plants” grow tall, then it should be because they have reason to. If they don’t, and somehow find some other strategy that works just as well… awesome!

It does mean a lot of extra thinking on our part though; instead of simply having different slots, we need applicable organisms to go “growing taller would be a beneficial adaptation because it increases my ability to capture energy and harms my competitors’ ability to capture energy” or “it would be beneficial because I’m currently in shadow (either due to terrain or taller organisms) and I want to increase my energy input” or even “growing taller would be a beneficial adaptation, but it’s very tricky to do so due to energy or resource limitations, so I will focus more on more easily tackleable issues” and also we need to make sure species don’t try to hog every energy source in the ecosystem by making sure it’s counterproductive to do so in some way.

Producer niches in particular are something I’ve worried about quite a lot. Since they’re all using the same energy/nutrient sources, wouldn’t only one species prevail due to the competitive exclusion principle? How do we get the biodiversity we see on terrestrial ecosystems on earth? Does size play a bigger factor than I’m realizing? Maybe intra-patch variation could help a bit.

I do like this, since it’s quite broad and could be used to contain energy from a number of sources, from living organisms, to carcasses and waste, to rocks in the environment (iron?) that need to be broken down in order to be utilized.


I think the main thing that bugs me about this system is that niches come from the patch, not other organisms.

I’ve been thinking about this on my own a bit and it’s definitely a tricky subject to figure out! I’ll wait for when you’re done communicating your concept since it’s probably gonna be a lot and I wanna fully understand your take on the system first. In the meantime, I can give some thoughts on how I see things working I guess. It’s more of an explanation of how an ecosystem would form with little in terms of implementation, so it might not be particularly useful.

Ecosystem formation

Let’s start with a totally barren patch, entirely devoid of life. In this state, it doesn’t have any niches.

The patch has a list of all abiotic energy sources inside it. This would include not only sunlight, but also compounds that indirectly grant energy like hydrogen sulfide, iron, and glucose (don’t forget glucose! in the vents, super early microbes will thrive off of it before it disappears for good and processes like chemosynthesis and iron chemolithoautotrophy become necessary)

It would also contain a compound pool, which accounts for all compounds contained within the patch, many of which are essential for the development of life; from gases in the air, to nutrients in the earth, to compounds dissolved in the water. There might also be some overlap between the compound pool and the energy sources. The pool would contain nitrogen in the form of compounds like ammonia, phosphates, and maybe even compounds we haven’t considered implementing yet, like calcium and sulfur.

Life, in other parts of the world, will soon come to colonize this patch. It could arrive here because life in some other patch evolved in a way that unintentionally grants it access to it, or it could have intentionally evolved to start exploiting this patch’s resources (which opens up a whole 'nother can of worms if species can see other patches in the world and “aim” for them)

The first species in this patch will be producers, because the only energy in this ecosystem is in the form of sunlight and certain compounds. They will require certain processes in order to exploit these energy sources – for instance, those that want to exploit the sun’s energy will need both photosynthesis (which produces glucose) and a process that allows them to make energy from glucose (even glycolysis, though orgs. with aerobic respiration will immediately have a huge advantage) Either way their productivity will be limited, however, because many nutrients will be locked in the earth therefore be very difficult to access.

The next species in this patch might be decomposers, because the dying producers are leaving behind an untapped source of leftover energy and nutrients (detritus). Decomposers help to return these nutrients to the compound pool, but this time in a more accessible nature, eventually creating a layer of fertile soil (alongside help with erosion and organisms that can break down rocks?) greatly boosting the productivity of the ecosystem. Again, the energy input hasn’t changed at all, but rather the amount of accessible nutrients did.

I’ve already expressed my confusions on plant niches so I won’t elaborate much here, but maybe different lineages of producers will show up in the patch, or those already there will diversify into different forms.

There still remains a massive untapped source of energy – living producers. (maybe also recently-dead producers that aren’t dead yet and can be shared with the decomposers? i’m getting ahead of myself) Primary consumers will eventually show up, and the diversity that already exists in this patch will allow quite a few new niches to arise. (what’s stopping some organism from showing up and just eating everything it can get its mouthparts on? Would that happen initially, only to eventually be pushed away from certain producer species by other organisms becoming more specialized to eat them?)

And so on, the cycle continues; some species might evolve (or arrive) that are capable of eating meat; if descended from herbivores, they might be omnivorous, occasionally catching smaller prey, but soon more species adapted purely for eating meat will appear until eventually it slows down and stops because the energy from the sun or whatever can only go so far.

And all the new organisms in this ecosystem will still leave behind energy in their carcasses and waste, and all of that (which doesn’t go to some scavenger or something) goes straight to the decomposers.

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When I mentioned there being 3 niches based on height, I just kinda pulled that number out of thin air. Also, my demo is going to show off, a Patch that is already somewhat developed. You could of course substitute 3 with an equation that adds niches as the game goes according to variations in altitude where energy can be found with different requirements of shade tolerance (this is why there is not only trees in the world). A niche is more to say how energy is divided in a given patch and how you can get it. An easier to understand example is, if there is energy in birds or some flying thing, then there should be a niche (or even niches) who can gain enough altitude to kill said birds and take their energy at the least.

Ok here’s some thoughts of my own, I have few ideas in terms of implementation I’m afraid but hopefully it’s still helpful in some way.

All/Full Concepts



Sunlight availability (that’s right it’s another desmos calculator)



Not much to see here (besides some cool creature silhouettes i guess)
These are some pretty basic (and bad) representations of food webs, defined only by colored rings around certain species that represent which species are preying upon them, without any regard for the nuances of how different predators would prey on the same organism, and how they may or may not compete.


Here I get into some ideas on nutrient/compound flow. This patch has certain amounts of different compounds both in the soil and the air, which are then stored in the producers who use them to grow, and then in the consumers who eat them, and so on. The energy produced by producers can only go so far and dies with the apex predators, while the flow of nutrients is fully cyclical: every organism here “creates” extra food sources for carcasses and (if applicable) waste, however only the blue apex predator’s is shown due to lack of space in this totally cramped diagram. Carcasses and waste would be eaten by decomposers, cycling the compounds back into the environment.

I also wondered how agents would be treated, and assumed they would just break down (during decomposition?) instead of endlessly bioaccumulating.

I quickly decide I’m getting ahead of myself, before immediately pursuing the idea further.



The cycle starts at the sun. Each patch has a total input amount of sunlight, representing how much light hits the entire surface of the patch in total. Some of this energy is harnessed by producers in the patch, based on their number, size, and how much light they reflect/absorb. The remainder is lost, either hitting non-productive parts of the ecosystem (like barren soil or a non-producer) or being reflected by producers.

Our producers take in sunlight, as well as vital compounds from the compound pool, both from the soil and the air. A majority of their gross energy intake is used up in respiration and lost through heat (forest green arrow turning red), while some of the net energy (lime green arrows) remains unexploited in detritus (lime green turning beige – the color may be misleading, these arrows still hold energy!), either in waste left by the organism due to imperfect digestion of material, or carcasses of the organism itself. (Detritus may be a confusing word for what I’m referring to, though I heard it technically applies?)
The remainder of that, probably about 10% of the input, is free for predators to consume, and this becomes their gross energy intake, and so on.

Note how the energy and compounds arrows are almost always paired together past the producers, as consuming any organic food source will also grant the consumer the nutrients present in it.

Nothing consumes living apex predators, so all of its net energy becomes detritus, which accumulates with the detritus of all other species in this patch, alongside it and the others’ compounds, which all goes straight to the decomposers. Nothing eats the decomposers in this patch, so all of their energy that isn’t lost as heat turns into detritus, which feeds into the total detritus pool, eventually cycling back to them.
Also note the transparent detritus arrows representing marine snow, if it existed in this patch (which it doesn’t). It comes in, some of it is able to be utilized, and the rest disappears (into another patch!)

Please note the incompleteness of this concept! It only represents a limited food chain, and I haven’t considered how things might work with a full food web. Also note the lack of any scavengers whatsoever.
Also there may be multiple, more specialized decomposers rather than one species that eats everything, however they should be quick to evolve to take advantage of any unexploited detritus, leaving hopefully nothing undecomposed in most developed ecosystems
I haven’t thought about what might happen if no decomposers exist in an environment. Nutrients in the soil may slowly be drained. (though how soil got there without decomposers in the first place is a bit questionable – see the “ecosystem formation” section in my previous post)…Would concentrations disappear over the course of several generations? Would the effects of this infertility start to take effect as soon as the generation where producers take root in the environment?



Here’s a multi-patch view of the movement of marine snow! Its ideas are similar to the previous diagram, except now each colored circle represents a patch, and the heart, its entire ecosystem.

The Epipelagic (topmost patch) is by far the most productive patch, producing the vast majority of the energy used in this water column, with the dim Mesopelagic just below it being a very distant second.

(The producers in) its ecosystem take in sunlight and compounds dissolved in the water (from the compound pool – same idea as last time, just with no soil). Most of the energy and compounds in the ecosystem flow normally, like shown earlier – most of it is lost as heat, the rest goes through its food web until reaching the apex predators, and most of the detritus is consumed by decomposers (and scavengers!), its compounds cycled back into the environment.
However, some of this detritus gets loose, represented by the compound and detritus arrows (purple and beige) splitting off and heading down into the Mesopelagic.

The Mesopelagic produces some of its own energy from the remaining sunlight, but it also gets a very small amount of its energy from some of the marine snow dropping down from above while their waste contributes to the remainder.

The Bathypelagic patch below it is unable to produce any energy, however it is still unable to sustain some life due to having even more marine snow than the Mesopelagic patch had to work with.

Finally, the Abyssopelagic floor patch is no different in terms of energy production, however it is different in that the detritus has no lower patches to escape to, giving detritivores and bottom feeders plenty of opportunity to consume all the marine snow that arrives in their patch.

As noted in the concept (along some questions about aquatic decomposition) it was kinda stupid of me to copy and paste the compound pool and compounds arrows for each patch. The arrow going to the lower ecosystems should’ve been smaller as there’s less life to use dissolved compounds, and in turn less compounds to recycle back into the water and less to lose as marine snow.
(Also, should the Abyssopelagic floor patch’s compound pool have a “soil” section? Where would decomposers recycle the compounds to? The water? The seafloor? A bit of both?)



Here’s some ideas on how producers in a “forest” ecosystem might compete for light. Each species casts a “shadow” on its environment, and the extent of that shadow depends on the species’ height, while its opacity depends on the species’ population and how effective it is at blocking light.
For instance, even though the first producer in my first “forest” (looks like a tall, desaturated, crooked “T”) is by far the tallest of them all, the shadow it casts is extremely weak because its population is very low.

(Total shadow opacity by height. Note the tall producer’s very faint shadow.)


I made a visual calculator (yes, it’s another desmos thing i spent way too much time polishing) for the availability of sunlight throughout a patch here.

The upper-right quadrant shows how the available energy from sunlight (y axis) changes as you increase your distance from the ground (x axis). Note the vertical dotted lines dividing the changes in sunlight intensity, color-coded to represent different species’ shadows.
The upper-left quadrant shows the percentage of the total input sunlight each species takes in.
The bottom-right quadrant shows the horizontal size of each organism compared to the patch’s land area, which together calculate the amount of light blocked by a certain species.

The blocking of light is also directly tied to the amount of sunlight a species gets in total.

Shaded regions of the patch could help to spawn new niches adapted for lower levels of sunlight. For instance, if a single lone producer species somehow grew tall and blanketed most of its ecosystem, there would still be an unexploited energy source in the dim sunlight slipping through the canopy, and thus niches waiting to be filled.

I thought maybe this pattern of energy being used in a “hierarchical” order could also be used to model how much energy consumers get from shared food sources, but it’s too orderly and doesn’t reflect competition whatsoever.
Finally I thought a bit about “animals” casting shadows too, which seems weird but I considered it for the sake of keeping our mechanics non-earth-centric, Just In Case. Just imagine a dense, massive herd of colossal beasts slowly lumbering across the continent – they’d definitely have an impact on the light levels of most biomes. Most producers would have to adapt to a constantly dimmer lifestyle, but some may take the challenge and attempt to grow so tall they tower over even the massive animals.
(Shadows would have to become less opaque as you get higher up in order to incentivize doing so for NPCs, so the sunlight availability graph might actually look something like this:)
image



Back to nutrient/energy flow!
I added some extra eaters-of-dead-stuff to our ecosystem from before: A scavenger (lanky greenish-yellow animal) that eats carcasses (but not dead plants) and a worm that eats poop.

Here, I broke down all the different forms of detritus into unique food sources, rather than treating it as just one. (Except I’m just now realizing that the fecavorous worm doesn’t have any, so let’s just say it’s immortal)
This allows different species to take advantage of largely different detritus sources, rather than having everything going to one decomposer species – now just some of everything is going to them. Again, I haven’t taken competition for shared food sources into account yet!

I also showed what marine snow would look like if it existed in this patch (it does not) – maybe even it too could be composed of different detritus sources, from small flakes to mostly-intact carcasses from above, like dead whales drifting to the bottom of the ocean.


That’s it for that big clump of concepts, but I still have another image made in an entirely different graphics program to get through:

I was intending to do a step-by-step demonstration of how life could colonize a barren niche, but I feel like I’m still missing a lot of pieces.


I start with a patch and define all its abiotic variables. Sunlight, temperature, and pressure should all be self-explanatory. However I fleshed out the compound pool idea a little more here: patches have “inexhaustible compounds,” which now that I’m thinking about it is a very inaccurate name. It includes the gases in the air (or water) and the minerals in the rock (only if your patch has land, mid-ocean patches just have water). Though their composition may be harder to change than that of soil, it is entirely possible for life to have an effect on them, especially gases (like what happened with the great oxygenation event, or is planned to happen with all the glucose in the vents)
Additionally, terrestrial patches may have a soil layer, which, if it exists at all, may just start out as the same minerals in the rock, however life may help to make it fertile over time. Precipitation also exists, which I’m still not too sure about.
This patch has no soil and very little water precipitation.

Now that we know the patch’s conditions, we know what sort of life can and can’t live there.
First, a helpful key:


The colored arrows represent compounds (or energy sources) flowing into various processes. The size of the arrowhead/triangle represents the amount required for the process to sustain the organism properly, while the thickness of the line before it represents the amount the organism is able to get from the patch. A hollow arrowhead means a process requirement isn’t being met, as do the red outlines and arrows. (I switch from one to the other kinda arbitrarily, sorry)


This species is better adapted to this patch due to its low water requirement and ability to break down rock for important compounds (and could be likened to lichen)


There may be situations where a patch’s conditions aren’t always constant, however. This patch lying in the intertidal zone is a good example, but the same idea could be used to account for differences between day and night, and all sorts of other different “states” of a patch.
This patch is underwater half the time, so it periodically switches between being terrestrial and aquatic (+benthic, because it includes a floor). Note how the variables change, and how gases are replaced by water and vice versa.
In order for a species to survive here, it will have to be able to survive in both versions of the patch. (At least for as long as the patch remains in one state for any one time. So holding your breath for 6 hours if you can’t breathe underwater is technically a viable strategy)


A comparison between two species, and how either fares in both the terrestrial state (left) and the aquatic state (right). Note how the bottom one is able to effectively extract necessary gases from both the water and the air.


Finally, here’s our very first patch and our very first species. Normally, ecosystems need to be fueled by producers adapted to converting things like sunlight or certain compounds into energy, but very early game, the vent patch will have massive amounts of glucose, essentially the (other) currency of energy, free for all sorts of species to take in and convert into ATP through glycolysis or respiration. This might actually discourage autotrophy for a few generations, as seeking out unique energy sources in order to produce a compound that’s already freely floating around might be suboptimal compared to floating around and basking in the free energy. However as the levels of glucose drop, species will have to adapt to survive their new environment; some will become producers, and those that don’t will either go extinct or learn to eat the producers.

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