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Retroposon evidence for an explosive radiation of Neoaves



Apologies to Mike Keesey; I intended to send this to the whole list:


Mike Keesey <keesey@gmail.com> wrote:

> So more than two major clades descend from the ancestral neoavian
> population.

I don't think that's the point of the paper. There _are_ hard
polytomies, where the lack of resolution is real and reflects multiple
lineages branching right off an ancestral population, but _Neoaves_ is
probably not one of them (Chojnowski et al. 2008, contra Poe & Chubb
2004). Incomplete lineage sorting simply means that there is a
conflict between gene trees and species trees, not that the polytomy
in question is non-resolvable. Internodes at the base of _Neoaves_ are
short (sometimes less than 1 million years long; Chojnowski et al.
2008) and more data are required to resolve them correctly, but large
molecular (and preferably nuclear intron) data sets could eventually
produce a reliable bifurcating tree.


References:

Chojnowski JL, Kimball RT, Braun EL 2008 Introns outperform exons in
analyses of basal avian phylogeny using clathrin heavy chain genes.
Gene 410: 89-96
http://www.biology.ufl.edu/earlybird/Publications/Gene-2008-Chojnowski-89-96.pdf

Poe S, Chubb AL 2004 Birds in a bush: five genes indicate explosive
evolution of avian orders. Evolution 58(2): 404-15

--
David Černý