orthogenesis, anagenesis, canalization

[Ken Kinman]

John Grehan wrote:
>The idea of evolution in one direction is not the "essence" of
>orthogenesis. The
>idea that orthogensis was restricted to a "linear" evolution was promoted
>by Darwinians and then denounced because evolution involved divergence.
**********************
     How confusing things can become when evolutionary terms themselves
"evolve".  I guess I really need to read that 1985 article in Systematic
Zoology.
     In the meantime, at the risk of looking foolish, I am wondering how the
terms anagenesis and cladogenesis might fit into this discussion.  And also
a concept often used in developmental biology, "canalization", which I
assume often tends to suppress cladogenesis in favor of anagenesis.  Is
there some relationship between the terms anagenesis and orthogenesis, or am
I mixing apples and oranges?  Perhaps it partly depends on which definition
you accept?
                    --------Ken Kinman


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