Re: Livezey and Zusi's big bird morph analysis [...]

[Michael Habib <mhabib5@jhmi.edu>]

> > What really makes me raise an eyebrow is that Livezey and Zusi not
> > only find a grebe/loon clade, but also a owl/falconiform clade
>
> This one, however, is also found by the last few molecular analyses, 
> as well as by Mayr taking *Messelastur* and the like into account.

I hadn't seen it show up in the molecular analyses; I'll take a look at 
that.  I was aware that Mayr found a raptorial clade using Messelastur 
and company.  However, Mayr's analyses seem to have a similar trend 
wherein the analyses consistently find groups previously considered 
"convergent" to be sister taxa instead (such as penguins and 
plotopterids).  When that keeps happening consistently, I start to 
question character choices.  He could be right on the money, I admit, 
I'm just a bit cautious about it at present.

> > a falconiform clade including cathartids
>
> What's so bad about that one?

There isn't anything bad about it, per se.  The problem is same as 
mentioned above; ie. the shear number of clades previously considered 
functionally convergent that this new analysis finds to be closely 
related.  It could be that, indeed, all of those homoplastic hypotheses 
were incorrect.  I remain skeptical at present, however, because it 
seems a bit suspect that *all* of those clades would end up being 
closely related after all.  It increases the likelihood that many of 
the characters they are using carry a high degree of functional signal. 
 And I do admit to a certain degree of personal bias; as rampant as 
functional convergence is in most groups, I suppose I've always 
expected to see similar trends in birds.  I have no qualms about it 
being shown otherwise, though.  More tests with expanded versions of 
the new dataset should help give weight one way or the other.  Until 
then, I'm a bit skeptical but still very impressed with the work that 
went into the Livezey and Zusi tree.


Cheers,

--Mike H.