BIRD PHYLOGENY, DNA, MOL. CLOCKS *YAWWN*

["D.W.Naish" <dwn194@soton.ac.uk>]

Ronald Orenstein helpfully posted part of the Sibley et al avian phylogeny as
determined by DNA-DNA hybridisation. Their assumption is that times involved in
their genetic experiments represent real divergence times amongst taxa, and thus
constitute accurate molecular clocks. Most of you will have a better idea of the
weaknesses in this scenario than I, so I guess it needs no further comment - -
but as has become evident through the recent debate on molecular clocks and the
conclusions drawn (Chip Pretzman's work), posted here, workers in different
fields will take sides.

A wide variety of data is needed for an accurate phylogeny, and this is nowhere
more evident than in Sibley et al's work. They seem to have answered, or at the
very least shed a new perspective on, various previously troublesome avian
relationships, but their data often does not agree as well with conclusions
drawn from anatomical/palaeontological evidence as many geneticists imply. 

For example... see this bit here..

> Class Aves
> Order Ciconiiformes
> Suborder Ciconii (the above minus the shorebirds and gulls)
>     Infraorder Ciconiides
>         Parvorder Ciconiida
>               Superfamily Phoenicopteroidea (flamingos)

For as long as ornithology has been a science, flamingos have been put into just
about every conceivable bird taxon that might house them - with waterfowl
(Anseriformes), with storks etc (Ciconiiformes), with waders etc
(Charadriiformes) blah blah blah.. - and the Sibley et al analysis puts them
together with 'traditional' Ciconiiformes, like ibises and storks. BUT (one of
my favourite party-lines) _Juncitarsus_, a little wader from the Eocene Messel
fauna, has *proved* that flamingos are derived stilts (recurvirostrids - avocets
in this family too, waders of the Charadriiformes)*. Incidentally, recently
published observations of nesting colonies of Banded stilts (_Cladorhynchus
leucocephala_) show that they do exactly the same weird thing as breeding
flamingos (huge colonies on flat islands in remote, hostile lakes), and thus add
some behavioral support to this. 

Sooo - phylogeny as elucidated through DNA is by no mean the last, or the right,
word. That's why so few ornithologists group the subjects in their books as per
Sibley et al. 

*the hypothesis put forward by Feduccia in 'Age of Birds' before the discovery
of _Juncitarsus_ I might add - Tim!!

"Sex? I'd rather have a cup of tea"

AMAZING ARNIE-ISMS NO. 3
"He's dead tired"

DARREN NAISH