Evolution of leaf anatomy and photosynthetic pathways in Portulacaceae

• Premise of the study: Portulacaceae is a family with a remarkable diversity in photosynthetic pathways. This lineage not only has species with different C 4 biochemistry (NADP‐ME and NAD‐ME types) and C 3 ‐C 4 intermediacy, but also displays different leaf anatomical configurations. Here we addressed the evolutionary history of leaf anatomy and photosynthetic pathways in Portulacaceae. • Methods: Photosynthetic pathways were assessed based on leaf anatomy and carbon isotope ratios. Information on the NADP‐ME and NAD‐ME C 4 variants was obtained from the literature. The evolutionary relationships and trait evolution were estimated under a Bayesian framework, and divergence times were calibrated using the ages obtained in a previous study. • Key results: C 4 photosynthesis is the main pathway in Portulacaceae. One clade (Cryptopetala), however, includes species that have non‐Kranz anatomy and C 3 type isotope values, two of which are C 3 ‐C 4 intermediates. The ancestral leaf anatomy for the family is uncertain. The analysis showed one origin of the C 4 pathway, which was lost in the Cryptopetala clade. Nevertheless, when a second analysis was performed taking into account the limited number of species with NAD‐ME and NADP‐ME data, a secondary gain of the C 4 pathway from a C 3 ‐C 4 intermediate was inferred. • Conclusions: The C 4 pathway evolved ca. 23 Myr in the Portulacaceae. The number of times that the pathway evolved in the family is uncertain. The diversity of leaf anatomical types and C 4 biochemical variants suggest multiple independent origins of C 4 photosynthesis. Evidence for a switch from C 4 to C 3 ‐C 4 intermediacy supports the hypothesis that intermediates represent a distinct successful strategy.