[Re:] families, biogeograhy, evolution

[Thomas Schlemmermeyer]

Still adding more points (probably rather questions than answers) to this
very interesting thread:

On (    Wed, 3 Mar 1999 22:13:10 -0500), John Grehan <jrg13 at PSU.EDU> wrote:

>A lot of "Neotropical" taxa are not Gondwanan elements at all, but Pacific.

Are gondwanian elements elements that show transpacific, transatlantic and
and transindian relations at the same time, and are restricted to the southern
hemisphere?

>Selection doesn't really have to be at the family level
>>but rather at the individual level (godknows what problem "group
>>selection" brings forth).
>
>It my be that families or other higher taxa represent the ancestors of
>the subordinate taxa, and that this ancestor not only constrains subsequent
>evolution, but also may contribute to a "bias" in the subsequent evolution
>of characters within the separate lineages of the descendant taxa.

I feel like disagreeing somewhat. In my eyes, families or higher taxa are
rather endpoints of evolution than ancestors.
As I tried to make clear, effective selection, giving rise to great evolutionary
novelties, should occurr on stages, when there is only one or few lineages.
I think this is sometimes called the concept of bottleneck.

Maybe due to such a bottleneck selection the peculiar and unique apomorphies
arose which define some higher taxa.

I agree that it would be interesting to look on how developmental, biochemical,
ontogenetic or other constraints of the ancestor helped to form
the unique shape of its descendants. Has this to do with theory of complex
systems?

I do not understand a lot of botany, but in zoology, it may make some sense
to speak of winner and loose faunas.
Any zoologist know examples? (I will look for that as well...

   cheers   Thomas