[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Mesozoic roots of parrots and passerine birds



evelyn sobielski <koreke77@yahoo.de> wrote:

> Interesting. The former looks like several loci adding up (they tend to be 
> "somewhere in the vicinity" according to most loci)

If "somewhere in the vicinity" means "they are both land birds", then
yes. I don't know of any locus other than FGB-int7 that supports a
sister-group relationship between Passeriformes and Picocoraciae,
though.

> Mousebirds are notoriously "jumpy" (and IONO how much to trust their 
> purported relationship to *parrots*).

Yes, the current land bird page on ToLweb
(http://tolweb.org/'Land_Birds'/26410) sums it up nicely: there are
eufalconimorphs, picocoracians, and many pesky little clades such as
mousebirds whose relationships are not well understood. However,
(parrots + passerines) win over (parrots + mousebirds) by a margin of
two nuclear genes and retroposon data.

> So it looks like this is not an aggregate signal, but more likely one locus' 
> particularly pronounced signal. Well I hope I'll find this out some time in 
> '12/'13. I'll let you know.

I look forward to it.

> I might compare signal distribution supporting particular "clades" ("loud and 
> clear" singleton vs weaker but aggregate signal) in various loci while I'm at 
> it. Has this ever been done, comparing multiple loci and seeing  where they 
> propose a phylogeny that diverges from e.g. majority-rule consensus?

I am not sure I understand you, but Ericson et al. (2006) presented
trees based on individual genes (showing which groupings are driven by
which loci and what clades are recovered only with all data combined),
as well as a tree based on all genes except for beta-fibrinogen; and
Hackett et al. (2008) performed individual gene partition and
gene-jackknifing analyses as well.

> The take home message of "Metaves" is apparently that there are strong 
> "signals" that are false, and that these cannot be foltered out by the usual 
> analysis protocol.

Well, how do we know that FGB-int7 is not the key to deep neoavian
divergences? I know that Morgan-Richards et al. (2008) "tested" and
"falsified" the Metaves/Coronaves divergence with mitochondrial data,
but it would be much more surprising to me if they corroborated it,
given that mtDNA and nuclear-DNA trees differ from each other in so
many aspects. Ericson et al. (2006) showed that four other nuclear
loci are sufficient to overthrow many shallow relationships that
resulted from an analysis of FGB-int7 alone (Bucerotidae + Trogonidae,
Passeriformes + Picocoraciae, Sphenisciformes + Phalacrocoraciformes,
Podargidae + Columbidae, Phoenicopteridae + Caprimulgidae, ...), but
18 are not enough to overthrow a single deep one (Metaves/Coronaves).
Is it not strange?

(But then, I'm ignorant of phylogenomics. Maybe it is not strange at
all, and I just said something really stupid. If so, please correct
me!)


References:

Ericson PGP, Anderson CL, Britton T, Elżanowski A, Johansson US,
Källersjö M, Ohlson JI, Parsons TJ, Zuccon D, Mayr G 2006
Diversification of Neoaves: Integration of molecular sequence data and
fossils. Biol Lett 2(4): 543-7

Hackett SJ, Kimball RT, Reddy S, Bowie RC, Braun EL, Braun MJ,
Chojnowski JL, Cox WA, Han K, Harshman J, Huddleston CJ, Marks BD,
Miglia KJ, Moore WS, Sheldon FH, Steadman DW, Witt CC, Yuri T 2008 A
phylogenomic study of birds reveals their evolutionary history.
Science 320(5884): 1763-8

Morgan-Richards M, Trewick SA, Bartosch-Härlid A, Kardailsky O,
Phillips MJ, McLenachan PA, Penny D 2008 Bird evolution: testing the
Metaves clade with six new mitochondrial genomes. BMC Evol Biol 8: 20
-- 
David Černý