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Re: Morpho v molecular (was Re: Tinamous: living dinosaurs)



> But what
> if (from a
> molecular perspective) problematic taxa are lurking
> somewhere among
> these thousands of species?  We sample the small
> groups (like extant
> hippopotamids and ratites) to exhaustion, because we need
> to, and
> because we can.  But when we recover the phylogenetic
> position of the
> Muridae based on a handful of murid species, there is no
> point testing
> all 600 murid species.  This isn't intellectual
> dishonesty, it's
> commonsense: let's focus our resources on the problematic
> taxa that
> are hard-to-place.  Nevertheless, what if there are
> card-carrying
> murid species that, based on molecular data, were to fall
> outside the
> Muridae?  We'll never know unless we test them
> all.  I'm not saying we
> *should* do this.  I'm just pondering the consequences
> of *if* we did.

_Panurus_ is not a "paradoxornithid" (which are sister to the core sylviids) 
but something fairly unique. But "paradoxornithid" samples being not well 
accessible outside China (where most of them live), _Panurus_ was used as 
stand-in for that group. So for the first half of this decade, it was believed 
that "paradoxornithids" are well removed from sylviids (and timaliids, which 
are sister to "paradoxornithids" + core sylviids).

Only since the studies of Cibois et al. (2006 onwards) is a good taxon 
selection of Sylvioidea even possible. There hasn't been a morphology-based 
study due to lack of material and difficulty of analysis, but the molecular 
results are already good enough to tell that the traditional (qualitative) 
classification was way off. 

It's obvious from the data that there was first a north-south split between the 
sylviids s.l. and the timaliids s.l. - almost certainly in eastern Asia -, with 
the former subsequently splitting east-west into, respectively, 
"paradoxornithids" and core sylviids. Himalayan orogeny and/or ice-age 
aridification of Central Asia seem to have something to do with it, as the 
fossil record (meager as it is) shows that the major lineages of Sylvioidea had 
separated by the mid-Miocene but probably did not originate before the 
Oligocene.


Regards,

Eike