Pterosaurs & paleogenomics

[Tim Williams <twilliams_alpha@hotmail.com>]

Organ, C.L. and Shedlock, A.M. (2008).  Palaeogenomics of pterosaurs and the 
evolution of small genome size in flying vertebrates.  Biology Letters 
FirstCite Early Online Publishing.  DOI: 10.1098/rsbl.2008.0491

http://journals.royalsociety.org/content/ll3905jh513jv850/fulltext.html


Abstract: "The two living groups of flying vertebrates, birds and bats, both 
have constricted genome sizes compared with their close relatives.  But nothing 
is known about the genomic characteristics of pterosaurs, which took to the air 
over 70Myr before birds and were the first group of vertebrates to evolve 
powered flight.  Here, we estimate genome size for four species of pterosaurs 
and seven species of basal archosauromorphs using a Bayesian comparative 
approach.  Our results suggest that small genomes commonly associated with 
flight in bats and birds also evolved in pterosaurs, and that the rate of 
genome-size evolution is proportional to genome size within amniotes, with the 
fastest rates occurring in lineages with the largest genomes.  We examine the 
role that drift may have played in the evolution of genome size within 
tetrapods by testing for correlated evolution between genome size and body 
size, but find no support for this hypothesis.  By contrast, we find evidence
 suggesting that a combination of adaptation and phylogenetic inertia best 
explains the correlated evolution of flight and genome-size contraction.  These 
results suggest that small genome/cell size evolved prior to or concurrently 
with flight in pterosaurs.  We predict that, similar to the pattern seen in 
theropod dinosaurs, genome-size contraction preceded flight in pterosaurs and 
bats."

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