Macroevolutionary trends and diversification dynamics in Atripliceae (Amaranthaceae s.l., Chenopodioideae): a first approach

BRIGNONE, NICOLÁS F.; POZNER, RAÚL; DENHAM, SILVIA S.

ANNALS OF BOTANY

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2022

0305-7364

* Background and aims. Atripliceae evolved and diversified by dispersals and radiationsacross continents on both hemispheres, colonizing similar semi-arid, saline-alkalineenvironments throughout the world. Meanwhile, its species developed different lifeforms, photosynthetic pathways, mono- or dioecy, and different morphological features inflowers, fruiting bracteoles, and seeds. In this study, we introduce a first approach to themacroevolutionary patterns and diversification dynamics of the Atripliceae to understandhow time, traits, speciation, extinction, and new habitats influenced the evolution of thislineage.* Methods We performed a molecular phylogenetic analyses and clade age estimation ofAtripliceae to apply time-, trait- and geographic-dependent diversification analyses, andancestral state reconstructions, to explore diversification patterns within the tribe.* Key results Opposite diversification dynamics within the two major clades of Atripliceae,Archiatriplex and Atriplex clades, could explain the unbalanced species richness betweenthem; we found low mean speciation rates in Archiatriplex clade and one shift to higherspeciation rates placed in the branch of the Atriplex core. This acceleration indiversification seems to have started before the transition between C3- and C4-metabolism, and before the arrival of Atriplex in the Americas, and matches with the MidMiocene Climatic Optimum. Besides, the American species of Atriplex exhibit slightlyhigher net diversification rates than the Australian and Eurasian ones. While time seemsnot to be associated with diversification, traits such as the life form, photosyntheticpathway, and plant sex may have played a role as diversification drivers.* Conclusions Traits more than time played a key role in Atripliceae diversification, andwe could speculate that climate changes could have triggered speciation. The extreme aridor saline environments where Atripliceae species prevail may explain its particularevolutionary trends and trait correlations compared with other Angiosperms and highlightthe importance of conservation efforts needed to preserve them as genetic resources todeal with climatic changes.