Molecular data and ploidal levels indicate several putative allopolyploidization events in the genus Potentilla (Rosaceae).

Mats Töpel,Torsten Eriksson,Magnus Lundberg,Bente Eriksen

doi:10.1371/currents.rrn1237

Abstract

Several naturally occurring hybrids in Potentilla (Rosaceae) have been reported, but no molecular evidence has so far been available to test these hypotheses of hybridization. We have compared a nuclear and a chloroplast gene tree to identify topological incongruences that may indicate hybridization events in the genus. Furthermore, the monophyly and phylogenetic position of the proposed segregated genera Argentina, Ivesia and Horkelia have been tested. The systematic signal from the two morphological characters, style- and anther shape, has also been investigated by ancestral state reconstruction, to elucidate how well these characters concur with the results of the molecular phylogenies. Six major clades, Anserina, Alba, Fragarioides, Reptans, ivesioid and Argentea, have been identified within genus Potentilla. Horkelia, Ivesia and Horkeliella (the ivesioid clade), form a monophyletic group nested within Potentilla. Furthermore, the origin of the proposed segregated genus Argentina (the Anserina clade) is uncertain but not in conflict with a new generic status of the group. We also found style morphology to be an informative character that reflects the phylogenetic relationships within Potentilla. Five well-supported incongruences were found between the nuclear and the chloroplast phylogenies, and three of these involved polyploid taxa. However, further investigations, using low copy molecular markers, are required to infer the phylogeny of these species and to test the hypothesis of hybrid origin.

Highlights

The position of genus Potentilla L. (Rosaceae) in the tribe Potentilleae, subfamily Rosoideae, has been corroborated by both morphological and molecular data [1] [2] [3]
We found style morphology to be an informative character that reflects the phylogenetic relationships within Potentilla
More recent studies [5] [6] [7] have added to the inter-generic classification of the tribe Potentilleae, but little has so far been published on phylogenetic relationships within Potentilla [2] [3] [8] [9] [10]

Summary

Introduction

The position of genus Potentilla L. (Rosaceae) in the tribe Potentilleae, subfamily Rosoideae, has been corroborated by both morphological and molecular data [1] [2] [3]. Wolf [4] presented the most extensive taxonomic work to date on the infra-generic relationships in the genus. He recognized 305 species as well as numerous naturally occurring hybrids and based his observations on morphological data. He divided the genus into six subsections based on the shape of the style and its position on the ovary and named them Rhopalostylae, Nematostylae, Closterostylae, Conostylae, Gomphostylae and Leptostylae (Fig. 1). More recent studies [5] [6] [7] have added to the inter-generic classification of the tribe Potentilleae, but little has so far been published on phylogenetic relationships within Potentilla [2] [3] [8] [9] [10].

Methods

Results

Discussion

Conclusion