Abstract

C4 photosynthesis has evolved on at least 66 independent occasions within angiosperms. This convergence is remarkable, as the C4 phenotype consists of a complex set of biochemical, cellular and anatomical adaptations. Although recent advances have been made into understanding the regulation and molecular evolution of C4 genes, many important questions surrounding C4 evolution remain: what is the number and order of evolutionary events required to generate C4? Have multiple C4 lineages evolved via the same molecular changes? What has facilitated the multiple origins of C4 photosynthesis? In this seminar I present the first computationally-driven approach towards defining the number and order of evolutionary events generating C4 in multiple lineages. Using data from C3, C4 and C3-C4 intermediate species from 44 independent studies, we modelled C4 evolution as a dynamic process within a space defined by 16 phenotypic characters. Using novel inferential machinery, we have characterised the evolutionary pathways on this space that are compatible with the observed phenotypes of C3, C4 and intermediate species. From this we can construct a more detailed blueprint of the number and order of changes required to generate C4 through evolution.