Symposia
Seeing the network for the trees: Methodological and empirical advances in reticulate evolution
Exploring the Possible Role of Hybridization in the Evolution of Photosynthetic Pathways in Flaveria (Asteraceae), the Prime Model of C4 Photosynthesis Evolution
Presenting Author
Diego Morales-Briones
Description
Flaveria (Asteraceae) is the prime model for the study of C4 photosynthesis evolution
and seems to support a stepwise acquisition of the pathway through C3-C4 intermediate
phenotypes, still existing in Flaveria today. Molecular phylogenies of Flaveria based on
concatenated data matrices are currently used to reconstruct the complex sequence of
trait shifts during C4 evolution. To assess the possible role of hybridization in C4 evolution
in Flaveria, we re-analyzed transcriptome data of 17 Flaveria species to infer the extent
of gene tree discordance and possible reticulation events. We found massive gene tree
discordance as well as reticulation along the backbone and within clades containing C3-C4
intermediate and C4-like species. An early hybridization event between two C3 species
might have triggered C4 evolution in the genus. The clade containing all C4 species plus
the C4-like species F. vaginata and F. palmeri is highly supported in our phylogenetic
analyses, but it might be of hybrid origin involving F. angustifolia and F. sonorensis
(both C3-C4 intermediate) as parental lineages. Hybridization seems to be a driver of C4
evolution in Flaveria and likely promoted the fast acquisition of C4 traits. This new insight
can be used in further exploring C4 evolution and can inform C4 bioengineering efforts.