families

[Thomas Pape]

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 and therefore we cannot
have descent with modification.

According to Pieter Winter: "there is a possibility that a whole family may
inherit [a] non-adaptive trait...". But families cannot replicate and
therefore cannot inherit anything (yet their constituent species replicate
and thus can inherit).

The constituent parts (species) of any family may share various traits and
for this reason "act" in a similar manner. The family itself, however, does
not act at all as this would imply some evolutionary, regulatory or
feed-back mechanism to govern the 'acting'.

Thomas Pape
Department of Entomology
Swedish Museum of Natural History
Box 50007
SE - 104 05 Stockholm
SWEDEN

thomas.pape at nrm.se
http://www.nrm.se/en/pape.html.en
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