families as biotic units?

[Richard Jensen]

For some insights to tis question, see

    Mohler, C. L. 1990. Co-occurence of oak subgenera: Implicatons for niche
    differentiation. Bull. Torrey Bot. Club 117: 247-255.

The two subgenera (now referred to as sections) of oaks native to the eastern
US (section Quercus = white and chestnut oaks; section Lobatae = red and black
oaks) have been treated in the past as genera and as subfamilies.  While this
does not get to the level of family, we must recall that many (most?; at least
in angiosperms) families (as another responder noted) are human constructs that
may bear no relation to real evolutionary units (i.e., putatively monophyletic
entities).

I doubt that these families act as units of selection.  That implies a degree
of cohesiveness that I don't perceive among the genera and species within the
family.  Are Fagus, Castanea, and Quercus (beech, chestnuts, oaks) evolving as
an entity or as separate groups?


--
Richard J. Jensen              TEL: 219-284-4674
Department of Biology      FAX: 219-284-4716
Saint Mary's College         E-mail: rjensen at saintmarys.edu
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