Data from: Plastome phylogenetics of tribe Eriachneae and evolution of C₄ photosynthesis in subfamily Micrairoideae (Poaceae)

Tribe Eriachneae in subfamily Micrairoideae is one of the least explored
of the ca. 22 C4 lineages in the grass family (Poaceae). Whereas many C4
lineages are more species-rich, more morphologically disparate, and wider
ranging than their C3 sisters, Eriachneae has fewer species, less
disparity, and covers a far smaller geographical area than its C3 sister
tribe Isachneae. Tribe Micraireae, which is C3 and sister to Eriachneae
and Isachneae, occupies habitats more similar to C4 Eriachneae than C3
Isachneae. Evolutionary analyses within the subfamily are hindered by the
lack of a phylogenetic framework for any substantial sample of species.
Additionally, only a handful of members of Micrairoideae have been tested
for photosynthetic pathway. This study presents the first well-resolved
phylogeny of Eriachneae based on full plastome sequences from almost half
of the species in the tribe. Photosynthetic pathway is tested for 47
species representing all three tribes of Micrairoideae using carbon
isotopes to test the assumption that C4 is restricted to Eriachneae.
Habitat preferences among the tribes are estimated using bioclimatic data,
with multivariate analyses showing that habitats of Micraireae and
Eriachneae are more similar to each other than either is to Isachneae, and
the range of environments is greater in Isachneae than in Eriachneae. All
measured Eriachneae are confirmed to be C4, and all Isachneae are C3.
Evolutionary interpretation of these results is necessarily preliminary,
and greater phylogenetic sampling in Isachneae is needed to estimate
diversification rates and ancestral habitats, but subfamily Micrairoideae
appears to be an interesting exception to general patterns of C4 evolution
in grasses.