Data from: C4 photosynthesis promoted species diversification during the Miocene grassland expansion

Identifying how organismal attributes and environmental change affect
lineage diversification is essential to our understanding of biodiversity.
With the largest phylogeny yet compiled for grasses, we present an example
of a key physiological innovation that promoted high diversification
rates. C4 photosynthesis, a complex suite of traits that improves
photosynthetic efficiency under conditions of drought, high temperatures,
and low atmospheric CO2, has evolved repeatedly in one lineage of grasses
and was consistently associated with elevated diversification rates. In
most cases there was a significant lag time between the origin of the
pathway and subsequent radiations, suggesting that the ‘C4 effect’ is
complex and derives from the interplay of the C4 syndrome with other
factors. We also identified comparable radiations occurring during the
same time period in C3 Pooid grasses, a diverse, cold-adapted grassland
lineage that has never evolved C4 photosynthesis. The mid to late Miocene
was an especially important period of both C3 and C4 grass
diversification, coincident with the global development of extensive, open
biomes in both warm and cool climates. As is likely true for most “key
innovations”, the C4 effect is context dependent and only relevant within
a particular organismal background and when particular ecological
opportunities became available.