Data from: Phylogeny and temporal diversification of the New World pond turtles (Emydidae)

We present a comprehensive multigene phylogeny and time tree for the
turtle family Emydidae. Our phylogenetic analysis, based on 30 nuclear and
four mitochondrial genes (23,330 total base pairs) sequenced for two
individuals for each of the currently recognized species of the subfamily
Emydinae and two species from each of the more species-rich Deirochelyinae
genera, yielded a well-supported tree that provides an evolutionary
framework for this well-studied clade and a basis for a stable taxonomy.
We calibrated an emydid time tree using three well-vetted fossils, modeled
uncertainty in fossil ages to reflect their accuracy in node dating, and
extracted stem/crown ages of a number of key diversification events. We
date the age of crown emydids at a relatively young 44 Ma, and the crown
age of both contained subfamilies at roughly 30 Ma. One deirochelyine
clade, which includes the genera Graptemys, Malaclemys, Pseudemys, and
Trachemys and contains 11% of all turtle species, dates to 21 Ma just
prior to the mid-Miocene climatic optimum, suggesting a potential causal
link between warm, moist conditions and rapid species accumulation of
these highly aquatic turtles. Both nuclear DNA data alone and in
combination with mitochondrial DNA support the monophyly of an inclusive
genus Emys containing the old world species orbicularis and trinacris and
the new world blandingii, marmorata and pallida. Given that all members of
this group were originally aligned in the genus Emys and that the age of
the clade is roughly equal to other emydine genera, we strongly support a
classification that places these five species in a single genus rather
than the alternative three-genus scheme (Emys (orbicularis, trinacris),
Actinemys (marmorata, pallida), Emydoidea (blandingii). The phylogeny and
resulting time tree presented here provides a comprehensive foundation for
future comparative analyses of the Emydidae that will shed light on the
historical ecology and conservation prioritization of this diverse
chelonian clade.