Terrestrial Ecosystems through Time, the money graph

It's been a while since I've read a paragraph that has wildly changed how I look at the world. I'm so jaded! Anyhow, here it is:

The Recent is a poor analogue for nearly all aspects of Paleozoic ecosystems except for those of the latest Permian. The lack of tetrapod herbivory, the narrow spectrum of plant-insect interactions, the importance of detritivory as the base of the food chain, and the strong partitioning of ecological resource space along widely divergent phylogenetic lines in plants are themes that run throughout most of the Paleozoic. Because of these and other fundamental differences, ecological models based on the present cannot be applied to Paleozoic examples in a uniformitarian manner.

Rough translation: life on land, until about 250 million years ago, was to modern land-based ecosystems much like what a mercantilist, caste-based economy is to a modern market economy. You know the kind: this ethnic group does this, while that ethnic group does that, and those guys? they take care of the horses; and there's never a winner without a loser. Of course, right after a modern ecology got established in the late Permian, the Earth got whacked with the largest documented extinction event ever. Ah well.

Comments

[The New York City Math Teacher]

But examples from the mid-Paleozoic on show that ecological unit assemblages, even when based on monocultural prime producers, are persistent and relatively static under stable conditions.

page 262, paragraph 4:
The wetland ecosystems of the Late Carboniferous, viewed from a shorter "ecological" time scale, do appear to have been persistent for remarkably long periods (2-3 My) in terms of taxonomic composition and dominance-diversity characteristics. Overall the persistence of the vegetation is even longer when viewed in ecomorphic terms. This suggests that such communities were resistent to invasion by new taxa with biomechanically superior traits, or that long-term ecosystem persistence suppressed the evolution of biomechanically superior forms by limiting safe sites for their ecological establishment. Biotic change appears to coincide with changes in prevailing climate, which accompanied the formation of Pangaea during the late Carboniferous and Permian. Although interpretation of temporal changes within floras and faunas is somewhat confounded (at million year time scales) by taphonomic factors, a basic signal can be detected: long intervals of persistence punctuated by short intervals of change. These patterns of relative persistence of ecosystems, resistance to biotically induced change, and major response to marked change in extrinsic conditions appear to characterize most of Post-Carboniferous time to the present.

So, I guess that, drawing the political economical analogy to which you allude more explicitly - organizations of trades and clades that fill the trades don't tend to get reorganized through intrinsic coevolutionary processes, but instead through exogenous crises.

Does that mean that Mother Nature is sipping tea with Karl R. and Rosa L.?

[Carlos]

So, I guess that, drawing the political economical analogy to which you allude more explicitly - organizations of trades and clades that fill the trades don't tend to get reorganized through intrinsic coevolutionary processes, but instead through exogenous crises.

Well, at that time. Also, it's not only the trade-clade thing that's peculiar, but the lack of interaction between the clades. What exogenous crisis caused greater plant-insect cooperation?

There's also a subtler theme here of terrestrial plant biomass and turnover. The tree habit seems to be a natural form for plant life to fall into; but we have grasslands now, instead of giant forests.

[A New York City Math Teacher]

From Late Carboniferous to the present, I thought the paragraph said.

What exogenous crisis caused greater plant-insect cooperation?

I'd guess that plant vascularization is a response to the combined selection pressures of herbivory and climate change. I'd guess further that the movement away from spore-mediated and vegetative propogation is also related to trade-diversification on the part of insect primary consumers. I also think it's a significant hint that detritivory predates herbivory during the same period.

Comes back to extrinsic climate factors then, as sea level excursions, changes in rainfall, and changes in temperature differentially stressed local biomes. Synergistic relationships between primary producer plants and their associated primary consumers (relationships pertaining to consumption systems and to patterns of propogation in stressed habitats) could act as a selection for plant and insect traits enabling higher forms of cooperation.

[Carlos]

NYCMT, I read that sentence as saying that particular ecosystems are persistent, not that the Paleozoic pattern is persistent.

The problem with the argument in your second paragraph is that it seems to be exactly the opposite of what happened. Look at current ecologies. The ones with the richest variety of plant-insect interactions are the ones whose environment has varied the least. Also, the timing is off.