Plato, Ecology and Vacant Niches. Or: What Does a Retired Professor do in His Spare Time?
Here I show what a retired professor does in his spare time. He popularizes science, as in this example!!
In a previous post I discussed Platonian archetypes and their application in ecology, with special emphasis on vacant (empty) niches. In this post I present an illustrated example.
Because the species illustrated exist in the mind of their creator, they must be considered to be archetypes. Both species have an organ, the balloon arising at their anteriors, which allows them to occupy a niche, the stratosphere, by lifting them into it whenever threatened by an enemy or in pursuit of an enemy. However, since both species have not yet made it into nature, this niche is still vacant. Of course, some people say that the niche does not yet exist, because the species have not yet occupied or “created” it. Ignore this nonsense! Scientific work should not be reduced to a squabble about semantics.
Note also that the vicious cycle continues. You may not have conquered a new niche to escape from enemies, but they will follow anyway.
April 22nd, 2008 at 11:44 am
Hmm, I don’t think ‘infinite’ vs. ‘finite’ is a good way to discuss this- it is too much like angels and pins!
Imagine Antarctica is a model of niche-space. We will make a mathematician’s approximation and consider it to be an infinite plane of ice. Somewhere in the middle is a cluster of Emperor Penguins, representing an ecosystem. Sure, there is in theory an infinite number of niches which they might occupy. But most species will not be able to move into a vacant niche at all: they will be hemmed in by others. There will only be a finite boundary around occupied niche space across which movement can occur.
(Not originally my point, but provoked by the analogy: moving into many of these possible niches will only be possible if a group of species collectively occupies a slab of niche space- otherwise they will freeze to death.)
(And, of course, you can fit fleas in between the penguins- but there is a physical limit on the possible smallest size of an organism, so this cannot proceed ‘ad infinitum’)
April 22nd, 2008 at 11:57 am
“Hmm, I don’t think ‘infinite’ vs. ‘finite’ is a good way to discuss this- it is too much like angels and pins!”
“Hmm, I don’t think ‘infinite’ vs. ‘finite’ is a good way to discuss this- it is too much like angels and pins!”
I don’t quite follow. Nowhere do I suggest that a niche is infinite, nor do I suggest that the number of niches is infinite. The point is whether evolution has filled all potential niches or not. Fossil evidence very strongly suggests that it has not.
Further, habitat is only one of the large number of niche dimensions. There is no niche without a habitat, but in addition you have, for example, seaonality, hosts (for parasites etc.), latitudinal range etc.etc. In my imaginary example of the “balloon animals”, they have to be able to withstand the extreme cold at high altitude and they must be able to store sufficient food. All these are niche dimensions, among many others. And only a particular part of each dimension is utilized by a species, i.e., each dimension has a finite extension for each particular species.
April 22nd, 2008 at 12:15 pm
Hmm, I am not sure where I got ‘infinite’ from. My apologies! I am reading things that are not there.
Of course I agree completely that evolution has not filled all potential niches. If that is the point we are arguing, we are arguing with very silly people! We can ignore everything else they say because they are obviously foolish persons.
My analogy was trying to map all of niche-space into a two or three dimensional continuum: I know there are so many other dimensions. And the point I am trying to make is this:
*Some bits of niche space are likely to be very densely occupied, so that the assertion ‘all niches are occupied’ would be a good one within that region.
*Some bits of niche space are likely to be largely unoccupied, so an early colonist (whether it is first to arrive on an island, or first to develop ballooning) has a lot of freedom to speciate.
April 22nd, 2008 at 12:37 pm
“*Some bits of niche space are likely to be very densely occupied, so that the assertion ‘all niches are occupied’ would be a good one within that region.”
Even this is not as clear-cut as it seems. Each species “creates” niches for others, e.g., for symbionts, parasites, commensals, predators, etc., and so there may even be more vacant niches in the species-rich tropics than in other regions. - But it is true of course for species at the same ecological “level”, e.g. insectivorous birds.
April 23rd, 2008 at 2:55 pm
I have just come across a reference to a book that deals with the problem of Plato and ecology:
Cambridge University Press
0521804302 - Philosophy and Biodiversity - Edited by Markku Oksanen and Juhani Pietarinen
http://assets.cambridge.org/052180/4302/excerpt/0521804302_excerpt.htm
Here is an excerpt:
“This volume pays special attention to Aristotle’s “mentor,†Plato. According to Arthur Lovejoy’s classical work The Great Chain of Being, Plato was the first to make extensive use of the idea that the actual world consists of all possible kinds of living beings. The world is a plenum formarum, full of all kinds of beings that ever can exist, and it is the better the more kinds it contains. This idea, which Lovejoy called the Principle of Plenitude, has played a very important role in Western philosophy (Lovejoy 1964; Knuuttila 1999). The principle was adopted by Christian theology, which for centuries taught that the omnipotent God has created the world as perfect and hierarchically structured, admitting of no disappearance of its constituents. It implies the idea that the number of species remains fixed because nothing can disappear from the great chain of being, or scala naturae: whenever and wherever a local extinction was noticed, it was nothing but a local matter and the missing species must have survived elsewhere (Moore 1999, 109).”
May 4th, 2008 at 5:04 pm
[...] This is the second in a series on idle professors. For the first click here. [...]