Farewell to Species - reticulation

[Thomas DiBenedetto]

Richard Jensen wrote:
a phenetic classification is often to be preferred when it comes
to stability and information content.
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It is my understanding that phenetics never found widespread favor precisely
because it was not a stable system, and that it failed to provide
information in its most useful context. Although the true phylogeny is not
something we can ever be certain to have discovered, it does stand as an
objective goal which can act as a stabilizing factor to the various studies
which attempt to approximate it. Using "overall similarity" as the criterion
for a classification seems to be obviously less stable, since the criterion
itself entails a subjective judgement.
Furthermore, I think that there is a widespread sense in the biological
community that the classification around which we build our naming system
should be reflective of phylogeny. The hierarchy of genealogical
relationships is, to me, obviously the context in which one must anchor ones
understanding of all of the characteristics of taxa. Evolution should be the
central organizing prinicple for the study of biological phenomena, and it
is beyond my comprehension why anyone would advocate for a non-phylogenetic
classification to be the basis of our naming system.

It is interesting that, beyond the issues of stability and information
content (both of which I think are very weak arguments for phenetics) the
best that can be said of a phenetic classification is that it sometimes
yields good historical groupings, despite the fact that it doesnt try to.
I would prefer to try for good historical groups, and to get them as often
as possible.

Tom DiBenedetto
tdib at dccmc.org