Punctuated Equilibria

The left hand most picture is what strict phyletic gradualism would predict for a complete fossil record; species evolve continuously, and, if the fossil record were perfect, we would see a nice smooth continuum in morphology in all lineages.The middle picture is supposed to represent Punctuated Equlibrium. According to that model, speciation events take place quickly (a few tens of thousands of years) in small locations, and so should be largely missing in the fossil record. What we would then see are lots and lots of transitional fossils (the black linettes) with small gaps between them.The picture on the right represents the creationists incorrect view of the fossil record -- very, very few transitionals with no clear indication of lineages.

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I agree, Minnemooseus - I don't think the diagram really captures the difference. That seems to be more about perceptions of the completeness of the fossil record than patterns of PE versus PG.I'm more accustomed to seeing diagrams like this one (from this site).

I would think "textbook gradualism" would be represented more by straight lines between known species fossils, for the same amount of change in time, while punkeek would be represented more by a zig-zag line between known species fossils --- IF you need a diagram to represent such development.I noticed the wikipedia had a whole section on misconceptions" There is still change in species over time, just at different rates, some better represented in the fossil record than others.

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Moose, it would be my interpretation thet the gaps in the lines are intended to represent the periods of change that are indeterminate w/r/t their exact time of occurrance or length of the period of transition.I think the intent of the diagram is to show only that smooth transtional lines cannot be safely inferred.I would further comment that the concept of 'punctuated equilibria' is a very useful one for shaking up conventional thought by virtue of the simple fact that it broke a rather iconic assumption that change was happening all around us in all species at *relatively constant rates*, when in fact the rates are very different among taxa and habitats and, most importantly, historical circumstances.