Bruce writes (very reasonably):

> At the (very great) risk of being put in my place in no uncertain terms,
>  I'll wander over to Wirt's territory and point out that the evolutionary
>  biology class may now be a poor exmaple. In last week's issue of the
>  journal _Science_, Richard Kerr describes an article in _Paleobiology_
>  which shows that better-adapted species don't usually drive out their
>  predecessors quickly -- even in direct competition with them -- unless
>  some catastrophic event intervenes. The researchers studied an event that
>  happened about 150 million years ago: a new species of a coral-like
>  animal, Bryazoa, arose with the ability to grow faster and change faster
>  than its 300 million year-old predecessor. Yet both species coexisted
>  quite well until 65 million years ago, when the impact-induced mass
>  extinction (the one that likely killed off the dinosaurs) cause a sudden
>  decline in numbers that the newer species recovered from more quickly.
>  Only then did the older species start a slow decline. A short summary of
>  Kerr's report may be found at
>  <http://www.sciencemag.org/cgi/content/summary/288/5465/414>.
>
>  Wirt and Gavin may be right (and I share their opinion of the economists'
>  recommendation), but evolutionary biology doesn't necessarily prove their
>  case.

The problem with all things philosophical, particularly when they deal with
complex systems, is coming to simple and true take-home lessons.

A better example than Bruce's bryozoans is the classical set of experiments
that were conducted by Carl Huffaker at the Univ of California, Riverside in
the late 1950's, when ecology was first being defined as a science. Huffaker
was an agricultural entomologist who specialized in mites and who tended to
work on extremely practical problems, particularly an idea called integrated
pest management. Nonetheless, his late-1950 experiments using mites are now
well known to every ecologist and are considered classical. The work was
published in the UofC journal, Hilgardia, in 1957, if I remember correctly.

Huffaker conducted a series of experiments in terraria with competing species
of mites. In the simplest, most sterile environments (a fixed arena of sand,
with no place to hide and no capacity to "carve out your own niche"), one
species of mite always competitively excluded the others, driving them to
local extinction.

However, as Huffaker made the environment more complex, by either adding
predatory mites or orange peels and the like to increase environmental
heterogeneity, he progressively increased the survival times of even the
non-competitive species. In the most extreme cases, where environmental
heterogeneity was high and species diversity complex, survival times were
extended to essentially infinity by providing for refugia and complex
population cycles.

Wirt Atmar