families

[Frederick W. Schueler]

Thomas Pape wrote:
>
> The original question by Allan Shanfield was:
>
> "Do families act as biological units?"
>
> Families are (or should be) monophyletic groups of species. They have a
> spatio-temporal circumscription and as such they exist.
>
> But do they "act as biological units"? The answer depends on what is
> meant by a biological unit - and what is meant by acting?
>
> Families do not evolve. Families cannot replicate cannot
> have descent with modification.
>

* isn't the question here really: "Are the apomophies used to
characterize [monophyletic] taxa as families the kind which have
predisposed the species in the family to predominantly retain membership
in a single ecological guild?"

I think the answer is that this is highly unlikely. Some families have a
conspicuous ecological unity, but others have evolved into niches which
are all over the map, and even if such ecological unity was a criterion
for the category "family" there's no assurance that the sister group of a
taxon so selected will have a parallel ecological unity in another guild.

fred schueler.
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