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RE: Tuataras are the roadrunners of molecular evolution.



I was wondering if the rate estimate might be inflated by assuming that the
early Holocene bones were ancestral to modern samples, whereas common sense
would suggest they might well be distinct species, or in any case that their
mitochondrial lineages had split much earlier.  I expected to be reassured
by reading the paper and seeing a cladogram and coalescence estimates (at
the very least), but I don't see this basic issue addressed either there or
in the online supplement, though there is mention there of sequences
clustering by geographic region regardless of date. Is the analysis OK, do
you think?

On the other hand, what would hyper-variable mitochondrial control regions
have to do with rate of morphological (or indeed physiological) evolution?

-----------------------------------------------
Dr John D. Scanlon, FCD
Riversleigh Fossil Centre, Outback at Isa
riversleigh@outbackatisa.com.au
http://tinyurl.com/f2rby
 
"Get this $%#@* python off me!", said Tom laocoonically.

-----Original Message-----
From: David Marjanovic [mailto:david.marjanovic@gmx.at] 
Sent: 02 March, 2008 9:11 AM
To: DML
Subject: Re: Tuataras are the roadrunners of molecular evolution.

Cool! I'll download it on Monday.

> The tuatara of New Zealand is a unique reptile that
> coexisted with dinosaurs and has changed little
> morphologically from its Cretaceous relatives.

Not so fast. For example, the closure of the lower temporal bar is 
secondary, and throughout the Mesozoic rhynchocephalian diversity was 
non-negligible...

> Tuatara have very slow metabolic and growth rates,
> long generation times and slow rates of reproduction.
> This suggests that the species is likely to exhibit a very
> slow rate of molecular evolution.

That's right, but these features are most likely all rather recent.

> tuatara have the highest rate of
> molecular change recorded in vertebrates.

:-o