Moa lineages divergence in PNAS

["calzola@iol.it" <calzola@iol.it>]

in case someone's interested

"Reconstructing the tempo and mode of evolution in an extinct clade of birds 
with ancient DNA: The giant moas of New Zealand" 

Allan J. Baker *, Leon J. Huynen , Oliver Haddrath *, Craig D. Millar ¶, and 
David M. Lambert  

ABSTRACT
The tempo and mode of evolution of the extinct giant moas of New Zealand remain 
obscure because the number of lineages and their divergence times cannot be 
estimated reliably by using fossil bone characters only. We therefore extracted 
ancient DNA from 125 specimens and genetically typed them for a 658-bp mtDNA 
control region sequence. The sequences detected 14 monophyletic lineages, 9 of 
which correspond to currently recognized species. One of the newly detected 
lineages was a genetically divergent form of Megalapteryx originally described 
as a separate species, two more were lineages of Pachyornis in southern and 
northeastern New Zealand, and two were basal lineages of South Island Dinornis. 
When results from genetic typing and previous molecular sexing were combined, 
at least 33.6% of the specimens were incorrectly classified. We used longer 
sequences of the control region and nine other mtDNA genes totaling 2,814 base 
pairs to derive a strongly supported phylogeny of the 14 moa
 lineages. Molecular dating estimated the most recent common ancestor of moas 
existed after the Oligocene drowning of New Zealand. However, a cycle of 
lineage-splitting occurred 4-10 million years ago, when the landmass was 
fragmented by tectonic and mountain-building events and general cooling of the 
climate. These events resulted in the geographic isolation of lineages and 
ecological specialization. The spectacular radiation of moa lineages involved 
significant changes in body size, shape, and mass and provides another example 
of the general influence of large-scale paleoenvironmental changes on 
vertebrate evolutionary history.


Filippo C



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