<< Any instance of convergent evolution that we perceive, no matter how small,
catches our attention as  evolutionary biologists; and I think this is
appropriate.  If you are interested in documenting evidence of adaptation
through natural selection, instances of convergence are a goldmine.  I do
not deny that selection is real, or that it can cause adaptive evolution,
including convergence.  There are two important point to make here, as I see
it.  First, correctly identifying evidence of the effects of past selection
is different from finding evidence that selection has been more important
than drift.  I think there is good reason, for example, to think that the
combination of selection and drift can be a far more potent adaptive process
than selection alone.  You did not actually point to the distinction between
drift and selection in your statement.  You only said that "the environment
has the last word."  

TH
I meant that selection had the final word.
And that which best adapted to the environment, no matter its drift change, was
that which was selected.



GH
If you did not intend this statement to distinguish
between drift and selection, then the implications meaning of your statement
is too vague to me to be able to respond intelligently to it.  I would agree
that all dissipative systems are responsive the external contingencies, at
least until they senesce into a more rigid state.  However, putting the
primary responsibility for design on the external environment seems to me to
take too much for granted the engine of work and change that is inside of
the system.  Second, it ignores alternative reasons for phenotypic
convergence. 

TH
Would you comment a little more on the above?





 Holistically-oriented developmental biologists, like Brian
Goodwin, recognize the existence of generic morphological outcomes that can
come about for different reasons (rather than, for example, shared selective
pressures).  I don't personally think that this point of view is a valuable
basis for understanding the extent of convergence manifested between
placental and marsupial mammals, but it could be an important part of that
story and should not be implicitly dismissed as if it did not exist.

Cheers,

Guy
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