Re: Nest predation

[John Bois <jbois@umd5.umd.edu>]

On Thu, 4 Jun 1998, chris brochu wrote:

> I would be far more
> concerned if it showed up in hundreds of putatively unrelated species.
> (Many thanks to the individual who corrected me on anseriform parasitism,
> by the way.)

Then the trait of parental care, since it shows up many species from
ants to humans is more problematic than nest parasitism?
I don't see how the trait showing up in _few_ putatively unrelated species
is more diagnostic than its presence in many. 

> Without a phylogeny, how would you know that nest parasitism is ephemeral?

But we've already constructed phylogenies based upon traits we have great
confidence in.  Would you overturn them on the basis of the trait of nest
parasitism?  All I'm saying is that some traits are more diagnostic than
others.  I agree with you that some behaviors _are_ diagnostic.  I
caution, though, that behavior is an evolutionarily maleable trait.  But I
do understand there are degrees and degrees of maleability (I recently
read a paper pointing out the unreliability of what has been traditionally
regarded as a cladistic Rosetta Stone, mammal teeth). 
I think my difficulty with the particular trait under discussion is that
it seems rather obviously ephemeral--but I suppose many have come a
cropper with such famous last words as that.  And being ephemeral (if it
is) we can move to adaptationist hypotheses such as: given certain
preexisting conditions trait X is likly to evolve at some frequency.