Molecular phylogeny of Cremolobus (Brassicaceae) supports the recognition of the new genus Yunkia and demonstrates the high habitat diversity of tribe Cremolobeae

Abstract

Cremolobus is a genus of seven species distributed along the Andes from northern Argentina and Chile northward into Colombia, and it inhabits a variety of different environments from humid habitats, such as the Yungas in Bolivia and Argentina or the Andean Paramos in Colombia and Ecuador, to the arid regions of the Sechura Desert in Peru. This genus, together with Aimara and Menonvillea, form the South American tribe Cremolobeae, which is morphologically defined by the indehiscent and 1-seeded schizocarpic silicles. To date, phylogenetic analyses in the tribe were mainly focused on Menonvillea and Aimara, but there are no prior studies on Cremolobus. In this paper, we first studied the phylogenetic placement of Cremolobus within Cremolobeae using ribosomal nuclear (ITS) and chloroplast (trnL-F, trnH-psbA, rps16 intron) data, including a comprehensive sampling of taxa. We also analysed morphological variation among species, emphasizing habitat adaptation and characterizing main lineages within the genus. Additionally, we studied the biome/habitat preference by the species and main lineages of Cremolobus and other members of the tribe, as well as characterized their climatic niches along the environmental space. Results from our analyses support the monophyly of Cremolobus excluding C. subscandens and C. bolivianus, which are transferred here to the new genus Yunkia. Furthermore, species of Cremolobeae inhabit a wide diversity of habitats along the Andes that are associated with high ecomorphological diversity and, therefore, differing in this aspect from the related tribes Eudemeae and Schizopetaleae. Climatic niche comparison recovered low niche overlap between main lineages of the tribe, but high similarity among species of the same lineage, suggesting the presence of phylogenetic niche conservatism in the tribe. Systematic implications of these results, including a key distinguishing Yunkia from the remaining genera of Cremolobeae and a synopsis of its species, are also provided.

Key words:

• Andes
• CES clade
• climatic niche evolution
• Cruciferae
• hypervolumes
• molecular phylogeny
• South America

Acknowledgements

We thank the directors, curators, and collection managers of the herbaria listed (Appendix S2). Special thanks to Lone Aagesen, Juan M. Acosta, Ariel Lliully Aguilar, and Huber Trinidad for their help in the field trips, Marcelo Moreno for preparing the line drawings, and Fábian Tricarico (Museum of Natural Sciences ‘Bernardino Rivadavia’) for his help in the scanning electron microscopy. Botanical collections were conducted under the permits: APN N° 1103 (Argentina), VMABCC N° 026/09 (Bolivia), SERNANP-PNH CUT N° 001297-2017 and SERFOR/DGGSPFFS AUT-IFL N°2016-036 (Peru).

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2020.1739777.

Associate Editor: Nadia Bystriakova

Additional information

Funding

This work was funded by ANPCyT (Agencia Nacional de Promoción Científica y Tecnológica) grant PICT-2016-0096, CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas) grant PIP-112-201301-00124CO, and the National Geographic Society grant #9841-16, for which we are profoundly grateful.