Forskning 
Rosoideae
Phylogeny of the Rosoideae (Rosaceae)
The aim of this project is to clarify the phylogenetic relationships and evolution within Rosoideae of Rosaceae (Flowering plants).
As shown by Morgan et al. 1994, Rosoideae was polyphyletic as traditionally delimited but when some aberrant groups were removed the rest showed good support as being monophyletic.
This more restricted Rosoideae contains a small number of large amorphous genera or generic groups, and a comparatively large set of small to medium sized caldes, commonly treated as separate genera. The large ones have often been split into smaller genera with a large leftover part. Relationships are obscured when species are split off from their close relatives in this way, leaving paraphyletic or even polyphyletic assemblages behind.
Focus of the project:
The phylogeny of species and monophyletic groups (genera) of Rosoideae as a whole.
The main large genera and their satellites are analysed in detail using morphological data and DNA sequence data. Currently, we are working on the following clades: Potentilla, Colurieae, Fragariinae, and Sanguisorbeae.
Rooting issues for Rosaceae and Rosoideae, and the position and phylogeny of certain key clades.
Monophyly of Potentilla
Potentilla, the largest genus, is variable in morphological features and its monophyly was seriously doubted. Several genera which are commonly split off seemed, based on general morphology, to have their closest relatives within Potentilla. In particular, this includes genera such as Duchesnea, Horkelia and Ivesia.
Our analyses of molecular sequence data (nuclear ribosomal ITS and chloroplast trnL/F intron and spacer) have identified the major clades of Rosoideae (Colurieae, Sanguisorbeae, Potentilleae, Rosa, Roperculina [Rosa+Sanguisorbeae+Potentilleae], and Sanpotina [Sanguisorbeae+Potentilleae]). These clades are well supported. Two main clades are supported within Potentilleae: Potentilla and Fragariinae. The latter includes Alchemilla, Fragaria and several segregates from Potentilla.
In terms of generic classification, a reasonable approach following the phylogeny would be to include Argentina (P. anserina and relatives) Duchesnea, Horkelia and Ivesia in Potentilla while excluding Comarum (P. palustris), Sibbaldiopsis (P. tridentata), Drymocallis (P. rupestris, P. arguta and allies), and Dasiphora (P. fruticosa). The excluded are found in the Fragariinae clade.
Colurieae and the Geum/Waldsteinia-group
The Dryadeae (sensu Hutchinson, 1964) has consistently been classified in the Rosoideae until the analysis of Morgan et al.(1994). They generally have achenes with elongate, often plumose, styles. Morgan et al. found that this tribe was polyphyletic and that Dryas and relatives should be removed from the Rosoideae s. str. but it is not clear where its position in Rosaceae is.
Geum, Waldsteinia, and Fallugia has been shown to form a monophyletic group (Morgan et al, 1994; Eriksson et al. 1998) within the Rosoideae. The distribution of morphological characters suggest that some previously recognised genera may be nested within others. Jenny Smedmark works on the phylogeny and evolution of this clade which is now called Colurieae (Smedmark & Eriksson, 2002).
Reticulate evolution due to allopolyploid speciation has been hypothesised to be an important aspect of the group (Gajewski, 1959). We use the single copy nuclear locus GBSSI-1 to investigate this, and the first study is currently in review. It corroborates the idea of allopolyploid evolution, but not any of the details as suggested by Gajewski.
Monophyly and biogeography of Sanguisorbeae
Sanguisorbeae (or Poterieae, sensu Hutchinson, 1964) includes more than a dozen genera which lack petals, seemingly forming (with the exception of Alchemilla) a tightly knit group. A few of these genera are large and some, lacking obvious synapomorphies, are candidates for paraphyletic groups. Our most recent analysis yields a well supported monophyletic Sanguisorbeae within which a petalous clade (Agrimoniinae) is sister to a apetalous clade (Sanguisorbinae). Malin S. Hibbs works on the phylogeny of Sanguisorbeae and currently focuses on the Andean tree Polylepis.
Relationships in the Fragariinae clade
One new clade, 'Fragariinae', emerged from our first ITS analysis of Rosoideae. It comprised Fragaria, Alchemilla and Sibbaldia among others, along with several species of Potentilla. When chloroplast data was added, this clade became well supported. Most of the Potentilla species which are found in this clade have from time to time been segregated into separate genera (Comarum, Drymocallis, Dasiphora, Sibbaldiopsis, Sibbaldianthe). The clade containing Sibbaldia and relatives is a current focus.
Involved in the Rosoideae project:
Torsten Eriksson
+46(8)545 91703
Jenny Smedmark
+46(8)545 91703
Project references:
Eriksson, T., and M. J. Donoghue. 1995. Is Potentilla monophyletic? A phylogenetic analysis of the Rosoideae (Rosaceae) using nuclear ribosomal ITS sequences. Amer. J. Bot. Suppl. 82:128 (abstract 366).
Eriksson, T., M. J. Donoghue, and M. S. Hibbs. 1998. Phylogenetic analysis of Potentilla using DNA sequences of nuclear ribosomal internal transcribed spacers (ITS), and implications for the classification of Rosoideae (Rosaceae). Pl. Syst. Evol.211: 155-179.
Smedmark, J. E. E., and T. Eriksson. 2002. Phylogenetic relationships of Geum (Rosaceae) and relatives inferred from the nrITS and trnL-trnF regions. Systematic Botany 27:303-317.
Eriksson, T., M. S. Hibbs, A. D. Yoder, C. F. Delwiche, and M. J. Donoghue. 2003. The Phylogeny of Rosoideae (Rosaceae) based on sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA and the trnL/F region of chloroplast DNA. International Journal of Plant Sciences 164:197-211.
Kurtto, A., and T. Eriksson. 2003. Generic delimitation and nomenclatural adjustments in Potentilla (Rosaceae). Annales Botanici Fennici 40:135-141.
Smedmark, J. E. E., T. Eriksson, R. C. Evans, and C. S. Campbell. 2003. Ancient allopolyploid speciation in Geinae (Rosaceae): Evidence from nuclear granule-bound starch synthase (GBSSI) gene sequences. Systematic Biology 52:374-385.
Other related references:
Gajewski, W. 1959. Evolution in the genus Geum. Evolution 13:378-388.
Hutchinson, J. 1964. The genera of flowering plants. Oxford University Press, Oxford.
Morgan, D. R., D. E. Soltis, and K. R. Robertson.1994. Systematic and evolutionary implications of rbcL sequence variation in Rosaceae. Amer. J. Bot. 81: 890-903.
Wolf, T. 1908. Monographie der Gattung Potentilla. Bibliotheca Botanica. 16 (Heft 71): 1-714.