Taxonomy & Evolution

Uncovering the evolutionary history of the Potentilla genus

Can new genomic tools help us to understand the evolution of polyploid species?

It can be challenging to reconstruct the more ancient branches of the tree of life, given complicating factors such as rapid speciation and hybridisation between species. The genus Potentilla (strawberry-like herbs in the flowering plant family Rosaceae) has been the subject of several phylogenetic studies but resolving its evolutionary history has proven to be particularly difficult. These previous analyses recovered six groups (the Argentea, Ivesioid, Fragarioides, Reptans, Alba and Anserina) but the relationships among some of these clades differ between data sets. Specifically, the Reptans clade, which includes the type species of Potentilla, has been noticed to shift position between plastid and nuclear ribosomal data sets. Low copy nuclear (LCN) markers could help to resolve relationships in this tricky genus, as they would allow us to better trace polyploidization and hybridization events.

The tormentil – Potentilla erecta – of the Reptans clade, is widespread in Europe and western Asia. Image credit: N.L. Persson.

In a new study published in AoBP, Persson et al. address known challenges about relationships in the Potentilla genus by analysing DNA sequences from different regions of the genomes of representative species. In addition to chloroplast and nuclear ribosomal data, they analysed four LCN markers to elucidate the position of the Reptans clade in the evolutionary history of the genus. They present a new well-supported phylogenetic tree that provides a fundamental tool for understanding the evolution of species and their traits in this plant group. Persson et al. found no evidence of hybridization or allopolyploidization in the evolution of Potentilla species, and suggest that other processes, such as incomplete lineage sorting, were likely involved in early evolution. They highlight that autopolyploidization events possibly occurred later in the Reptans and Ivesioid clades. The authors conclude by highlighting the importance of LCN markers in the study of the evolutionary history of polyploids, revealing patterns that could not have been discovered with chloroplast or nuclear ribosomal data alone.

Researcher highlight

Nannie Linnéa Persson is currently finishing up her PhD thesis in plant systematics at the University of Bergen, Norway. Her main research interest concerns the evolutionary history of polyploids, and the thesis deals with reticulate evolution among cinquefoils (the genus Potentilla in the rose family, Rosaceae).

Nannie grew up in Växjö, Sweden, completed a master thesis on grass systematics at Stockholm University in 2015, and later worked at the Natural History Museum in Stockholm digitalizing the algae collection, before moving to Bergen. She is also a photographer (https://nannie.se/), and a dedicated naturalist (https://inaturalist.org/people/nannie).

Future plans include post-doctoral work in plant systematics, and later she wishes to work with natural history collections.

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