Turtle draft genomes support sister-group to archosauria (free pdf)

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com

A new online open-access paper:


Zhuo Wang, Juan Pascual-Anaya, Amonida Zadissa, et al.
The draft genomes of soft-shell turtle and green sea turtle yield
insights into the development and evolution of the turtle-specific
body plan.
Nature Genetics (advance online publication)
doi:10.1038/ng.2615
http://www.nature.com/ng/journal/vaop/ncurrent/abs/ng.2615.html
http://www.nature.com/ng/journal/vaop/ncurrent/pdf/ng.2615.pdf


The unique anatomical features of turtles have raised unanswered
questions about the origin of their unique body plan. We generated and
analyzed draft genomes of the soft-shell turtle (Pelodiscus sinensis)
and the green sea turtle (Chelonia mydas); our results indicated the
close relationship of the turtles to the bird-crocodilian lineage,
from which they split ~267.9–248.3 million years ago (Upper Permian to
Triassic). We also found extensive expansion of olfactory receptor
genes in these turtles. Embryonic gene expression analysis identified
an hourglass-like divergence of turtle and chicken embryogenesis, with
maximal conservation around the vertebrate phylotypic period, rather
than at later stages that show the amniote-common pattern. Wnt5a
expression was found in the growth zone of the dorsal shell,
supporting the possible co-option of limb-associated Wnt signaling in
the acquisition of this turtle-specific novelty. Our results suggest
that turtle evolution was accompanied by an unexpectedly conservative
vertebrate phylotypic period, followed by turtle-specific repatterning
of development to yield the novel structure of the shell.


Also:

http://phys.org/news/2013-04-turtle-genome-analysis-evolution-turtle-specific.html