Lots to think about here.
In ecological or evolutionary terms, one can think of this in terms of robustness: robust ecosystems, those that can best handle 'perturbations', are also those that can best accommodate diversity and change; in evolution, phenotypic robustness actually allows for a maximum of genotypic change, change that cannot be 'seen' by natural selection because it takes place below the level at which selection can exert pressure on it. I've not studied the ecological analogs of this (perhaps @fdrake will have more to say), but I can only imagine the same applies.
Biodiversity itself can have a regulatory effect. I think the most extreme example of this is a monocultural crop. If a field consists of a single crop everywhere in it, perturbation through disease can quickly wipe out the whole crop. Diversifying land use in the field can increase both single crop yields and the stability of the crop to disease and other externalities like climate change. There's a nexus of articles on Wiki about similar topics, surrounding
polyculture and agro-ecology.
This paper is about biodiversity and stability but asks the questions in terms of scope changes (local,regional,global biodiversities) and
spatial biodiversity (link totally not biased since it's my old boss' paper). In the latter paper, you can see the effect of fortuitous/unfortuitous ways of thinking about space and locality methodologically (which I mentioned in terms of zonation).
AFAIK the mechanisms that link biodiversity to stability are still being researched, so it's far from 'settled science'.
I should add that thinking about methodological constraints in the same manner as ecological realities as I did in the boundary post is very heterodox and probably needs to be taken with a grain of salt.
Next post:
The question of paramatizaion is facinating to me - like, what is the exact status of a 'parameter'? Is it simply 'epistemic', 'merely' a way to gain a handle on things? But it can't be merely that because it has to in some way 'track' a real change occuring in the 'thing/process' itself. So what exactly is happening when you see an 'optimization' of a parameter along a certain dimension in a time series?
Do you mean the time series obtaining a local maximum through 'optimisation' or do you mean an ecological model obtaining a local maximum through optimisation? The relationship of the latter to an ecological model is more a matter of model fitting and parameter estimation than how a parametrised mathematical model of an ecology relates to what it models. The parameters are 'best in some sense' with respect to the data.
Also
@csalisbury:
My intuition - probably along the lines of Csal's distinction between the 'in-itself' and the 'for-itself' - is that most parameters are 'emergent';
But then something happens when a variable in the system can relate to that cycle by, to paraphrase Csal, by 'reflexively taking it's own parameters as a variable that can be acted upon': so humans will cultivate food so that we don't have to deal with - or at least minimize the impact of - cycles of food scarcity and die out like wolves with too few deer to prey on. This is the shift from the 'in-itself' to the 'for-itself', where the implicit becomes explicit and is acted upon as such. And this almost invariably alters the behavior of the system, which is why, I think, the two descriptions of the 'X’wunda trade system' (quoted by Csal) are not equivalent: something will qualitatively change if the system itself 'approaches itself' in Friedman's way
I personally wouldn't like to think about the 'modelling relation' between science and nature in terms of the 'for-itself' acting representationally on the 'in-itself'. Just 'cos I think it's awkward. Will give an example: if you plant a monoculture and it gets destroyed by disease, when the 'in-itself' of the crop gets destroyed, we can say it's because of the 'for-itself' of the vulnerability of the crop to disease in our way of thinking about it. The crop's vulnerability to disease acts as a pattern in nature and a pattern in thought, and there's some kind of functional equivalence of terms. Even if nature sees only the individual plants and their inter-relations, this 'crop through iterated conjunction' still works like the 'crop' which satisfied the properties of monocultures. But this aversion of mine might be because I don't understand Kant very well. Could either of you map the distinction for me insofar as it relates to ecological models?
Of course you can ask how a certain process 'knows' if the level is too high or too low, but it's all just mechanism: because these systems are 'looped', the end product itself influences the rate at which that product is produced. Thus - at another analytic level - the usual alternating-periodic 'sine wave' pattern of certain preditor-prey cycles, which I'm sure you're well, well farmilar with:
I think what allows the aggregation of prey/predators in the model to work like something in nature is that in terms of
exchangability. Let's take wolves and rabbits, the specifics of the wolves don't matter too much since availability of food and food amount required operate on each wolf individually
in the same way as they operate on the the group (scaled up). Rabbits are the same, the specifics don't matter too much insofar as they need to get food, how much food there is and how many predators there are. A way of putting this might be 'the individual is an aggregate of size 1' in these circumstances.
Methadologically, I suppose, the ecological question is always: does the system see itself in the way I'm describing? And if not, how careful must I be with respect to the conclusions I'm trying to draw with my data? And of course one can relate all of this to Heidegger's 'ontological distinction' and the so-called horizon of intelligibility where beings appear as beings, and animals with are 'without world' etc etc. I think a really interesting project would be to try and think these two things together, but I'm not ready to pursue that here! And yeah, all of this should indeed be linked to your other question: "How does nature learn what to care about?"
I think ecology has some complications that aren't present in simpler relationships between model and world. I'm not sure I could make a list of them all, but there's always a difficulty in measuring properties of ecosystems precisely in a manner useful for modelling. It isn't the same for chemistry.
An example,
the Haber process. It works so long as there's air, hydrogen, a catalyst, and a cooling procedure. The terms in the description of the process aren't abstractions, they're the real thing. The algorithm works on real inputs (air,hydrogen) and produces real outputs (ammonia).
Why it works might be conceptually ladened, but procedurally the description it embodies is equivalent to the described, if that makes sense. I don't think the same is true of ecological parameters.