families

[Hugh Wilson]

I guess flowering plant families are, in terms of rank and
circumscription, 'human constructs', but this applies to any entity
defined by Science.  While concordance between these 'constructs' and
reality can vary through time, I think that key structural features
held by genera of many flowering plant families link them as part of
a single lineage.  If this linkage (and lineage) is 'real' (something
more than a human construct), then it follows that key (defining)
characters have (or had) a selective function relative to the
phyletic path of the family lineage, competing lineages, and
'cooperating' lineages (maybe insects).  The Asteraceae has, for
instance, had a significant global phylogenetic impact; as indicated
by its current diversity and distribution.

On  3 Mar 99 at 8:06, LUCIANO PAGANUCCI DE QUEIROZ
<lqueiroz at CASCAVEL.UEFS.BR> wrote:


> I think that the question of families as biological units must be addressed
> by different ways than the present debate:
>
> 1. Species and populations have biological reality and, consequently, some
> properties exclusive of these levels. Then, I think it is not possible to
> generalize attributes as competition to supraspecific (human construct)
> levels. If we think a bit more on biological processes can anyone envisage
> a process by which a family act, as a whole, as a selection unity ?
>
> 2. The taxonomic concentration of some families in particular areas, as the
> Rhizophoraceae in mangroves or Dipterocarpaceae in South-eastern Asian
> forests may give the false view that the family is acting as a selection
> unity. If we see this question from a phylogenetic perspective, the
> competitive ability of the family may be seen as one (or some) apomorphic
> traits of its ancestral species that gave this ability to this species. If
> these traits were inhereted by the descendent species the so called
> competitive ability of the family is in fact the effect of enhanced
> competitivity of their component species.
>
> LUCIANO
>
>

Hugh D. Wilson
Texas A&M University - Biology
h-wilson at tamu.edu (409-845-3354)
http://www.csdl.tamu.edu/FLORA/Wilson/homepage.html