<It seems most of the discussion here in regards to evolutionary models is
about what some might  call 'directional selection' (my wife's term) or
what I more loosely refer to as a constant evolutionary model but we should
also keep in mind that there is the 'punctuated' model of evolution.>

As far as I know the two main models are gradualism (Slow and steady over
time) and punctuated equilibrium (periods of little change followed by
rapid change, in part based on the old model of catastrophism).

Directional selection is generally selection in one direction (toward one
extreme of a trait), e.g. selection in favor of larger bees, or smaller
bees, or more hygenic etc.  This is opposed to stabilizing, diversifying,
or sexual selective pressure (there's other names for the same thing as
well).

I resent a different post on the same subject, darn gmail keeps getting me
with excessive quotes thanks to their hidden text.

Jeremy
West Michigan

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