Molecular phylogenetics of Euploca (Boraginaceae): homoplasy in many characters, including the C4 photosynthetic pathway.

Frohlich, Michael W; Sage, Rowan F; Craven, Lyn A; Schuster, Sebastian; Gigot, Guillaume; Hilger, Hartmut H; Akhani, Hossein; Mahdavi, Parastoo; Luebert, Federico; Weigend, Maximilian; Thulin, Mats; Doyle, Jeff J; Doyle, Jane L; Vogan, Patrick; Forrest, Alan; Fulcher, Timothy K; Devey, Dion S; Chase, Mark W

We present a phylogenetic analysis using plastid (matK , rbcL) and nuclear (nrITS) DNA for diverse Euploca spp. (formerly Heliotropium section Orthostachys) from the worldwide distribution of a genus and including species encompassing the wide physiological and morphological diversity of the genus. Our results indicate that some remarkably complex features arose multiple times in parallel in Euploca , including attributes of its subsections under section Orthostachys , notably plants that, above ground, consist almost entirely of inflorescences. To elucidate in greater detail the distribution of C4 species in Euploca and Heliotropium s.s. we made > 800 δ 13C determinations, including some from the traditional genus Tournefortia. We greatly increase the number of proven C4 species in Euploca , but found none outside Euploca. Of the tested Euploca spp. c. 28% are C3 or intermediate in carbon fixation pathway. Our phylogenetic results indicate four parallel/convergent acquisitions of C4 photosynthesis or fewer origins with subsequent loss in some species.

MOLECULAR phylogeny; BORAGINACEAE; HOMOPLASY; CARBON fixation; BIOLOGICAL extinction; PLANT species diversity

Botanical Journal of the Linnean Society, 2022, Vol 199, Issue 2, p497

0024-4074

Academic Journal

10.1093/botlinnean/boab082