Data from: Evolutionary bursts in Euphorbia (Euphorbiaceae) are linked with photosynthetic pathway

The mid-Cenozoic decline of atmospheric CO2 levels that promoted global
climate change was critical to shaping contemporary arid ecosystems.
Within angiosperms, two CO2-concentrating mechanisms (CCMs)—CAM and
C4—evolved from the C3 photosynthetic pathway, enabling more efficient
whole-plant function in such environments. Many angiosperm clades with
CCMs are thought to have diversified rapidly due to Miocene aridification,
but links between this climate change, CCM evolution, and increased net
diversification rates (r) remain to be further understood. Euphorbia
(∼2000 species) includes a diversity of CAM-utilizing stem succulents,
plus a single species-rich C4 subclade. We used ancestral state
reconstructions with a dated molecular phylogeny to reveal that CCMs
independently evolved 17–22 times in Euphorbia, principally from the
Miocene onwards. Analyses assessing among-lineage variation in r
identified eight Euphorbia subclades with significantly increased r, six
of which have a close temporal relationship with a lineage-corresponding
CCM origin. Our trait-dependent diversification analysis indicated that r
of Euphorbia CCM lineages is approximately three-fold greater than C3
lineages. Overall, these results suggest that CCM evolution in Euphorbia
was likely an adaptive strategy that enabled the occupation of increased
arid niche space accompanying Miocene expansion of arid ecosystems. These
opportunities evidently facilitated recent, replicated bursts of
diversification in Euphorbia.