families

[PIETER WINTER]

LUCIANO DE QUIROS wrote:

=22If 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 ?

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.=22

In this scenario the ancestral species=27 apomorphy is interpreted as an =
adaptive trait. In that case I would agree that the derived species, even =
if all of them maintained this trait, merely inherit it and do not have =
any increasing advantage.

The one process which one can invoke and speculate on, however, is the =
hitch-hiker effect (as I understand it at least), where an apomorphy =
develops in the ancestral species which has no adaptive significance at =
that stage, but is linked genetically to a different, adaptive trait. As =
long as this link is not lost along the way, and till such time has =
elapsed that we can speak of a family (or any supra-specific taxon for =
that matter), there is a possibility that a whole family may inherit this =
non-adaptive trait.
At this stage the environmental selective pressures could change so that =
the once non-adaptive trait now has adaptive value. Only in this (probably =
very far-fetched) hypothetical scenario, would I envisage that a family =
act as a unit by means of a simultaneously increasing advantage over =
species of other families. The condition would then be that the same =
environmental change occurs at the same time over the total geographic =
range of the family. Seems like a tall order to me, but is perhaps food =
for thought.

Any comments?

Pieter Winter