Welcome to what should probably be a named regular feature here at Dynamic Ecology: Jeremy’s Half-Baked Analogies to Economics!*
I had a thought and I’m not sure what to make of it, or even if it’s original. So I thought I’d share it in the hopes that a reader can enlighten me.
In economics, inflation is a reduction in the purchasing power of a unit of money. It’s often measured as an annualized percentage change in a price index, a weighted average of the prices of a “basket” of goods and services. The contents of the basket obviously need to reflect what consumers actually buy.
Measuring inflation is trickier than you might think. The problem is that consumers react to price changes by changing the quantities they buy. If the price of some good or service rises, consumers often will substitute some other good or service instead. If you ignore this fact, you will badly overstate the extent to which price increases of some goods erode the real purchasing power of a unit of money. But conversely, if you take this fact too seriously, you will understate inflation. Apparently**, economists haven’t come up with a perfect solution to this problem.
I think there’s an analogy here to trying to measure the strength of competition for resources, for instance by measures of resource use overlap. If competition for a given resource (say, a given prey species) gets stronger, so that the resource becomes scarcer on a per-consumer basis, we expect that consumers will respond by substituting other resources instead. That’s the logic of character displacement. Which makes it tricky to summarize the “strength” or “intensity” of competition in terms of a number quantifying how much resource a consumer can “buy” with each unit of foraging effort.
This is why it’s generally a bad idea to use indices of resource use overlap as measures of the strength of competition. Say the abundance of your competitor increases for some reason, causing some of the resources you previously were consuming to become scarce on a per-capita basis. So you move somewhere else, or switch to consuming some other resources instead, thereby reducing or even eliminating overlap with your competitor. But does that mean you’re no longer experiencing competition? If you say yes, isn’t that like saying that there’s no inflation so long as consumers are spending their money on something?
Has anyone else drawn this analogy before, or tried to pursue it further? For instance, has anyone ever looked at whether the price indices economists have developed have applications in ecology? Or is the analogy too loose or half-baked for that?
*Mathematicians are said to be machines for turning coffee into theorems. I’m more of a machine for turning Pepsi into half-baked analogies between ecology and economics. 🙂
**meaning: “as far as I can tell from Wikipedia and a blog post I once read”