Torsten Eriksson

• PhD
• Professor (Associate) at University of Bergen

UsingDNAsequencedatafromnuclear ribosomal ITS in combination with plastid trnLF spacer and trnL intron data, we show that Sibbaldia is a polyphyletic assemblage. It falls into five separate clades of Potentilleae, three within Fragariinae and two within Potentilla (Potentillinae sensu Soja ´k).Toa large extent, our results are congruentwithSoja ´k’...

Rubiaceae are one of the largest families of plants, with ;13,000 species. In this study, we have estimated the phylogeny for 534 Rubiaceae taxa from 329 genera with up to five different chloroplast regions by Bayesian analysis. It resulted in a highly resolved tree with many strongly supported nodes. There is strong support for the three subfamili...

Aim When hypotheses of historical biogeography are evaluated, age estimates of individual nodes in a phylogeny often have a direct impact on what explanation is concluded to be most likely. Confidence intervals of estimated divergence times obtained in molecular dating analyses are usually very large, but the uncertainty is rarely incorporated in b...

Potential events of allopolyploidy may be indicated by incongruences between separate phylogenies based on plastid and nuclear gene sequences. We sequenced two plastid regions and two nuclear ribosomal regions for 34 ingroup taxa in Fragariinae (Rosaceae), and six outgroup taxa. We found five well supported incongruences that might indicate allopol...

Low copy gene phylogenies and ploidy levels reveal a possible history of allopolyploidy in Sibbaldia and close relatives.

Data from whole genome sequencing of 29 species from all genera in Fragariinae were analysed (4258 nuclear genes and plastome sequences). Clades are well supported, but conflicts remain, suggesting that hybridization, in combination with polyploidy, has played a role in the evolutionary history of the Fragariinae.

Classification of Potentilla L. has varied considerably through time. Some authors have collapsed all of the Potentilleae tribe into a single genus, while others have divided it into more than 20 genera. All those classifications, except for the one that collapsed them all, have rendered the genus Potentilla polyphyletic. We discuss Potentilla from...

The genus Potentilla (Rosaceae) has been subjected to several phylogenetic studies, but resolving its evolutionary history has proven challenging. Previous analyses recovered six, informally named, groups: the Argentea, Ivesioid, Fragarioides, Reptans, Alba and Anserina clades, but the relationships among some of these clades differ between data se...

Background: Most cinquefoils (Potentilla L., Rosaceae) are polyploids, ranging from tetraploid (4x) to dodecaploid (12x), diploids being a rare exception. Previous studies based on ribosomal and chloroplast data indicated that Norwegian cinquefoil (P. norvegica L.) has genetic material from two separate clades within Potentilla; the Argentea and th...

Premise: Microsatellite markers were developed for sandmyrtle, Kalmia buxifolia (Ericaceae), to facilitate phylogeographic studies in this taxon and possibly many of its close relatives. Methods and results: Forty-eight primer pairs designed from paired-end Illumina MiSeq data were screened for robust amplification. Sixteen pairs were amplified...

The reticulate evolutionary history of Potentilla norvegica L.

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 a...

Unlabelled: Premise of the study: The Condamineeae have in previous molecular studies been shown to be part of an early-divergent clade within the subfamily Ixoroideae, together with the tribes Calycophylleae, and Hippotideae, and genera of the former Cinchoneae and Rondeletieae. Generic relationships within this clade have, however, remained la...

Alchemilla (the lady's mantles) is a well known but inconspicuous group in the Rosaceae, notable for its ornamental leaves and pharmaceutical properties. The systematics of Alchemilla has remained poorly understood, most likely due to confusion resulting from apomixis, polyploidisation and hybridisation, which are frequently observed in the group,...

Biological nitrogen fixation (BNF) is an important source of nitrogen input in many natural ecosystems. The rice production today depends on large amounts of chemical nitrogen fertilizer, which is an environmental hazard in rice producing areas. Better exploitation of BNF is one way to reduce the use of chemical nitrogen fertilizer in the future. I...

Although recent methodological advances have allowed the incorporation of rate variation in molecular dating analyses, the calibration procedure, performed mainly through fossils, remains resistant to improvements. One source of uncertainty pertains to the assignment of fossils to specific nodes in a phylogeny, especially when alternative possibili...

Phylogenetic relationships among 88 genera of Rosaceae were investigated using nucleotide sequence data from six nuclear (18S, gbssi1, gbssi2, ITS, pgip, and ppo) and four chloroplast (matK, ndhF, rbcL, and trnL-trnF) regions, separately and in various combinations, with parsimony and likelihood-based Bayesian approaches. The results were used to e...

Molecular phylogenetic studies have shown that the evolutionary history of Geum L. has been strongly influenced by allopolyploidy, and they have indicated widespread homoplasy in morphological traits within the group. This study of gynoecial development in Colurieae shows that fruits with jointed styles develop similarly. In early stages of develop...

A previous phylogenetic study of paralogous nuclear low-copy granule-bound starch synthase (GBSSI) gene sequences from polyploid and diploid species in Geinae indicated that the clade has experienced two major allopolyploid events in its history. These were estimated to have occurred several million years ago. In this extended study we test if the...

Cyanobacteria are one of the main components of the microbiota in rice paddy fields and significantly contribute to its fertilization. The diversity and changes of the cyanobacterial assemblage were investigated during a rice growth season and after harvest in a paddy field located in Fujian Province, China. The cyanobacterial populations were anal...

A phylogenetic analysis of selected symbiotic Nostoc strain sequences and available database 16S rDNA sequences of both symbiotic and free-living cyanobacteria was carried out using maximum likelihood and Bayesian inference techniques. Most of the symbiotic strains fell into well separated clades. One clade consisted of a mixture of symbiotic and f...

To test the molecular dating results and biogeographic in-terpretations reported by Conti et al. (2002), R. G. Moyle reanalyzed our published dataset of 13 rbcL sequences rep-resenting Melastomataceae and five small taxa: the Southeast Asian Crypteroniaceae (the C clade) and their western Gond-wanan sister clade, formed by the South American Alzate...

Biogeographical and paleontological studies indicated that some ancient Gondwanan taxa have been carried by the rafting Indian plate from Gondwana to Asia. During this journey, the Indian island experienced dramatic latitudinal and climatic changes that caused massive extinctions in its biota. However, some taxa survived these conditions and disper...

Biogeographical and paleontological studies indicated that some ancient Gondwanan taxa have been carried by the rafting Indian plate from Gondwana to Asia. During this journey, the Indian island experienced dramatic latitudinal and climatic changes that caused massive extinctions in its biota. However, some taxa survived these conditions and disper...

The Begoniaceae consist of two genera, Begonia, with approximately 1400 species that are widely distributed in the tropics, and Hillebrandia, with one species that is endemic to the Hawaiian Islands and the only member of the family native to those islands. To help explain the history of Hillebrandia on the Hawaiian Archipelago, phylogenetic relati...

The principle of the evolutionary cul-de-sac is commonly invoked to explain the apparent lingering existence of once-diverse groups of organisms. Maybe that principle itself has had its day.

To reconstruct the phylogenetic position of the extinct cave lion (Panthera leo spelaea), we sequenced 1 kb of the mitochondrial cytochrome b gene from two Pleistocene cave lion DNA samples (47 and 32 ky B.P.). Phylogenetic analysis shows that the ancient sequences form a clade that is most closely related to the extant lions from Africa and Asia;...

The phylogeny of Rosoideae was investigated using 44 species. Here we report new sequence data from the chloroplast trnL/F region as well as an increased sample of species. The analysis of these new data, along with previously used data from the nuclear ribosomal internal transcribed spacers (ITS), significantly increased resolution as well as conf...

A nuclear low-copy gene phylogeny provides strong evidence for the hybrid origin of seven polyploid species in Geinae (Rosaceae). In a gene tree, alleles at homologous loci in an allopolyploid species are expected to be sisters to orthologues in the ancestral taxa rather than to each other. Alleles at a duplicated locus in an autopolyploid, however...

The phylogeny of Rosoideae was investigated using 44 species. Here we report new sequence data from the chloroplast trnL/F region as well as an increased sample of species. The analysis of these new data, along with previously used data from the nuclear ribosomal internal transcribed spacers (ITS), significantly increased resolution as well as conf...

In the Atlas Florae Europaeae, Comarum, Dasiphora, Drymocallis and Sibbaldianthe, which are commonly included in Potentilla, are recognized as independent genera. Due to the generic delimitation adopted and some taxonomic remodellings, the following new nomenclatural combinations are proposed and discussed: Drymocallis corsica (Soleir. ex Lehm.) Ku...

Phylogenetic analyses and molecular dating estimates based on chloroplast DNA sequences were used to establish the relationships of the southern and Southeast Asian Crypteroniaceae and elucidate their biogeographic history. Maximum parsimony and likelihood analyses of rbcL sequences suggested that Crypteroniaceae should be restricted to Crypteronia...

Phylogenetic analyses and molecular dating estimates based on chloroplast DNA sequences were used to establish the relationships of the southern and Southeast Asian Crypteroniaceae and elucidate their biogeographic history. Maximum parsimony and likelihood analyses of rbcL sequences suggested that Crypteroniaceae should be restricted to Crypteronia...

This is a molecular phylogenetic study of the group formerly known as Dryadeae, based on DNA sequences from the internal transcribed spacers, ITS, of nuclear ribosomal DNA and the trnL intron and the trnL-trnF intergenic spacer of the chloroplast. A total of 1.9 kb, for 26 ingroup species, were analyzed using parsimony and model-based Bayesian infe...

Hybridization has long been considered a source of taxonomic complexity in Rubus. This study uses molecular data to examine natural hybridization between R. caesius, a facultatively agamospermous tetraploid of subgenus Rubus (blackberries) and R. idaeus, a sexual diploid of subgenus Idaeobatus (raspberries). Both species are widespread in Europe, a...

To further clarify phylogenetic relationships within Dipsacales, we analyzed new and previously pub-lished rbcL sequences, alone and in combination with morphological data. We also examined relationships within Adoxaceae using rbcL and nuclear ribosomal internal transcribed spacer (ITS) sequences. We conclude from these analyses that Dipsacales com...

Linnaean binomial nomenclature is logically incompatible with the phylogenetic nomenclature of de Queiroz and Gauthier (1992, Annu. Rev. Ecol. Syst. 23:449-480): The former is based on the concept of genus, thus making this rank mandatory, while the latter is based on phylogenetic definitions and requires the abandonment of mandatory ranks. Thus, i...

The circumscription ofPotentilla has varied widely. To investigate the monophyly ofPotentilla and the phylogenetic relationships of associated genera we used nuclear ribosomal internal transcribed spacer (ITS) DNA sequences. Fourteen species ofPotentilla (sensuWolf 1908) were included, some of which represent proposed segregate genera (such asArgen...

We inferred the phylogeny of Sambucus and Adoxa (Adoxoideae, Adoxaceae) based on nucleotide sequences of the internal transcribed spacer (TTS) region of nuclear ribosomal DNA, preliminary morphology, and a combination of the two data sets. Our morphological analysis implies that Adoxa is nested within Sambucus, based primarily on herbaceous habit a...

Stern, M. J. & Eriksson, T.: Symbioses in herbaria: recommendations for more positive interactions between plant systematists and ecologists. – Taxon 45: 49‐58.1996. – ISSN 0040‐0262. Herbarium collections have traditionally been used primarily by systematists, including monographers and writers of floras. It is suggested here that herbarium materi...

The palaeotropical genus Athroisma (Asteraceae, Heliantheae) is revised for the first time, and its general morphology is described. Twelve species and two subspecies distributed in East Tropical Africa, Madagascar, and in Asia from north-eastern India to the Sunda Islands are recognized. Four new species are described (A. inevitabile and A. pusill...

The palaeotropical genus Athroisma (Asteraceae, Heliantheae) is revised for the first time, and its general morphology is described. Twelve species and two subspecies distributed in East Tropical Africa, Madagascar, and in Asia from north-eastern India to the Sunda Islands are recognized. Four new species are described (A. inevilabile and A. pusill...

The palaeotropic genusBlepharispermum (Asteraceae, Heliantheae) is revised for the first time. Fifteen species from Africa, the Arabian Peninsula, Madagascar, India, and Ceylon are recognized. Two new species are described, viz.B. arcuatum andB. canescens. Aspects of the systematic position and morphology of the genus are discussed. A hypothesis of...

Eriksson, T.: The systematic position of the Blepharispermum group (Asteraceae, Heliantheae). ‐ Taxon 40: 33–39. 1991. ‐ ISSN 0040‐0262. The three genera Athroisma, Blepharispermum and Leucoblepharis have previously been placed in the Inuleae. They constitute a monophyletic group whose inclusion in the Inuleae is rejected, on the basis of morpholog...

The purpose of this study was to determine (1) the nectar plant utilization of a population of Leptidea sinapis L. by following individual adults in their natural habitat, and (2) whether L. sinapis pollinates the flowers visited by collecting insects immediately after their visiting flowers and identifying pollen grains on the proboscis, palpi, he...

To reconstruct the phylogenetic position of the extinct cave lion (Panthera leo spelaea), we sequenced 1 kb of the mitochondrial cytochrome b gene from two Pleistocene cave lion DNA samples (47 and 32 ky B.P.). Phylogenetic analysis shows that the ancient sequences form a clade that is most closely related to the extant lions from Africa and Asia;...