| 1. |
- Backlund, Maria, 1969-
(författare)
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Phylogenetic Studies in the Gentianales – Approaches at Different Taxonomic Levels
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with phylogenetic relationships at different taxonomic levels. All the plants studied are or have been included in the order Gentianales, which comprises about 17 200 species. The phylogenies are based on parsimony analyses of nucleotide sequence data (DNA) from different regions in the chloroplast genome, but morphological characteristics have also been studied. Analyses of sequence data from the genes rbcL and ndhF provide the interfamilial structure of the order Gentianales, shown to comprise the families Apocynaceae (incl. Asclepiadaceae), Gelsemiaceae, Gentianaceae, Loganiaceae, and Rubiaceae. Exclusion of certain genera from the Loganiaceae is confirmed and their phylogenetic positions are clarified. Some of these genera remain within the Gentianales, while others belong to other orders. Exclusion of the tribe Buddlejeae from the Loganiaceae is confirmed, and a monophyletic group formed by Buddleja, Emorya, Gomphostigma, and Nicodemia is recognized and placed in the Lamiales. The Loganiaceae s.str. forms, after these exclusions, a strongly supported monophyletic group comprising 13 genera. The tribe Paederieae in the family Rubiaceae is analysed using sequence data from the regions rbcL gene, rps16 intron, and the regions trnT-F, and is shown to be paraphyletic. These results lead to a new circumscription of Paederieae comprising the genera Leptodermis, Paederia, Serissa, and Spermadictyon. The tribe Putorieae is reestablished with the single genus Plocama, including 34 species. Aitchisonia, Choulettia, Crocyllis, Gaillonia, Jaubertia, Pseudogaillonia, Pterogaillonia, and Putoria are reduced to synonyms of Plocama based on the molecular analyses and morphological studies. The Mediterranean species of the re-circumscribed Plocama, previously segregated as the genus Putoria, are revised. Two species, Plocama calabrica and P. brevifolia, are recognized, their synonymics are established, and seven lectotypes are selected.
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| 2. |
- Hedrén, Mikael, et al.
(författare)
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Acanthaceae
- 2006
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Ingår i: Flora of Somalia, vol 3. - 1 84246 099 4 ; 3, s. 374-454
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Somalian vegetation is rich and varied, and covers one of the most arid regions of Africa. Volume 3 completes the angiosperms, and includes an index to all of the genera described in the four volumes.
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| 3. |
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| 4. |
- Hedrén, Mikael
(författare)
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New species and combinations in Acanthaceae from Somalia
- 2006
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Ingår i: Willdenowia. - 0511-9618. ; 36:2, s. 751-759
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Tidskriftsartikel (refereegranskat)abstract
- Six species from Somalia, Barleria albomarginata, B. dentata, B. glaucobracteata, B. ilicifolia, Hypoestes cinerea and Justicia carnosa, are described as new to science, J. arenaria is proposed as a new name for J. ovalifolia var. psammophila and the new combination B. brevispina is proposed for B. linearifolia var. brevispina.
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| 5. |
- Hedrén, Mikael, et al.
(författare)
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Patterns of polyploid evolution in Greek marsh orchids (Dactylorhiza; Orchidaceae) as revealed by allozymes, AFLPs, and plastid DNA data
- 2007
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Ingår i: American Journal of Botany. - 0002-9122. ; 94:7, s. 1205-1218
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Tidskriftsartikel (refereegranskat)abstract
- Polyploidy is common in higher plants, and speciation in polyploid complexes is usually the result of reticulate evolution. We examined variation in nuclear AFLP fingerprints, nuclear isozymes, and hypervariable plastid DNA loci to describe speciation patterns and species relationships in the Dactylorhiza incarnatalmaculata polyploid complex (marsh orchids; Orchidaceae) in Greece. Several endemic taxa with restricted distribution have been described from this area, and to propose meaningful conservation priorities, detailed relationships need to be known. We identified four independently derived allopolyploid lineages, which is a pattern poorly correlated with prevailing taxonomy. Three lineages were composed of populations restricted to small areas and may be of recent origins from extant parental lineages. One lineage with wide distribution in northern Greece was characterized by several unique plastid haplotypes that were phylogenetically related and evidently older. The D. incarnatal maculata polyploid complex in Greece has high levels of genetic diversity at the polyploid level. This diversity has accumulated over a long time and may include genetic variants originating from now extinct parental populations. Our data also indicate that the Balkans may have constituted an important refuge from which northern European Dactylorhiza were recruited after the Weichselian ice age.
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| 6. |
- Hedrén, Mikael
(författare)
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Plastid DNA haplotype variation in Dactylorhiza incarnata (Orchidaceae): evidence for multiple independent colonization events into Scandinavia
- 2009
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 27:1, s. 69-80
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Tidskriftsartikel (refereegranskat)abstract
- The early marsh orchid, Dactylorhiza incarnata (L.) Soo s. l., grows in medium-rich to rich fens and marshes over much of Europe and parts of Asia. The species is highly polymorphic and different forms may grow together at the same site. In the present study, I tested the hypothesis that these forms represent different migrant populations that have colonized Scandinavia independently of each other, possibly from different source areas. Accessions from Scandinavia and elsewhere were screened for variation at three size-variable plastid marker loci, one polyA repeat, one polyA-polyTA-polyT repeat and one 9 bp indel. Ten haplotypes were defined on basis on the combined variation pattern. The common occurrence of several haplotypes in southern Scandinavia and adjacent areas to the south and the east of the Baltic Sea suggests that D. incarnata has been dispersed on repeated occasions across the Baltic. Also, there was some correlation between haplotype composition and morphological form on the island of Gotland, in agreement with the independent colonization hypothesis. Material from northernmost Sweden, Finland and northwest Russia was fixed for a single widespread haplotype, indicating that populations in this area are located farther away from the Pleistocene refugia. Dactylorhiza incarnata ssp. lobelii from southwest Norway was characterized by a haplotype that was not encountered elsewhere in Scandinavia. Given its proximity to British populations dominated by the same haplotype, it is suggested that D. incarnata ssp. lobelii was established independently of the other Scandinavian populations, from coastal refugia located in western Europe.
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| 7. |
- Hedrén, Mikael, et al.
(författare)
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Polymorphic populations of Dactylorhiza incarnata s.l. (Orchidaceae) on the Baltic island of Gotland: morphology, habitat preference and genetic differentiation.
- 2009
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 104, s. 527-542
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Organisms may be polymorphic within natural populations, but often the significance and genetic background to such polymorphism is not known. To understand the colour polymorphism expressed in the diploid marsh-orchids Dactylorhiza incarnata, morphological, habitat and genetic differentiation was studied in mixed populations on the island of Gotland, supplemented with genetic marker data from adjacent areas. Methods A total of 398 accessions was investigated for plastid haplotype and three nuclear microsatellites. Morphometric data and vegetation data were obtained from a subset of 104 plants. Key Results No clear pattern of habitat differentiation was found among the colour morphs. Within sites, the yellow-flowered morph (ochroleuca) was slightly larger than the others in some flower characters, whereas the purple-flowered morph with spotted leaves (cruenta) was on average smaller. However, populations of the same colour morph differed considerably between sites, and there was also considerable overlap between morphs. Morphs were often genetically differentiated but imperfectly separated within sites. Most populations were characterized by significant levels of inbreeding. The ochroleuca morph constitutes a coherent, highly homozygous sublineage, although introgression from purple-flowered morphs occurs at some sites. The cruenta morph was genetically variable, although Gotland populations formed a coherent group. Purple-flowered plants with unspotted leaves (incarnata in the strict sense) were even more variable and spanned the entire genetic diversity seen in the other morphs. Conclusions Colour polymorphism in D. incarnata is maintained by inbreeding, but possibly also by other ecological factors. The yellow-flowered morph may best be recognized as a variety of D. incarnata, var. ochroleuca, and the lack of anthocyanins is probably due to a particular recessive allele in homozygous form. Presence of spotted leaves is an uncertain taxonomic character, and genetic differentiation within D. incarnata would be better described by other morphological characters such as leaf shape and stature and size and shape of lip and spur.
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| 8. |
- Hedrén, Mikael, et al.
(författare)
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Polyploid evolution and plastid DNA variation in the Dactylorhiza incarnata/maculata complex (Orchidaceae) in Scandinavia.
- 2008
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Ingår i: Molecular Ecology. - 0962-1083. ; 17:23, s. 5075-5091
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Tidskriftsartikel (refereegranskat)abstract
- The Dactylorhiza incarnata/maculata complex (Orchidaceae) was used as a model system to understand genetic differentiation processes in a naturally occurring polyploid complex with much of ongoing diversification and wide distribution in recently glaciated areas in northern Europe. Data were obtained for 12 hypervariable regions in the plastid DNA genome. A total of 166 haplotypes were found in a sample of 1099 plants. Allopolyploid taxa have inherited their plastid genomes from D. maculata s.l. Overall haplotype diversity of the combined group of allopolyploid taxa was comparable to that of maternal D. maculata s.l., but populations of allopolyploids were also more strongly differentiated from each other and contained lower numbers of haplotypes than populations of D. maculata s.l. In addition to haplotypes found in extant D. maculata s.l., the allopolyploids also contained several distinct and widespread haplotypes that were not found in any of the parental lineages. Some of these haplotypes were shared between widespread allopolyploids. Divergent allopolyploids with small distributions did not seem to originate from local polyploidization events, but rather as segregates of already existing allopolyploids. Genetic diversification of allopolyploid Dactylorhiza is the result of repeated polyploid formation, secondary hybridization and introgression between already existing polyploids and extant representatives of parental lineages, hybridization between independently derived polyploid lineages, and phyletic diversification in the group of allopolyploids. Although some polyploid taxa must have evolved after the last glaciation, genetic material from the parental lineages has been transferred continuously for longer periods of time. This combination of processes may explain the taxonomic complexity encountered in Dactylorhiza and other polyploid complexes distributed in previously glaciated parts of Europe.
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| 9. |
- Hedrén, Mikael
(författare)
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Speciation and relationships in Dactylorhiza
- 2005
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Ingår i: Svensk Botanisk Tidskrift. - 0039-646X. ; 99:2, s. 70-93
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Most of the Scandinavian members of the orchid genus Dactylorhiza are included in the D. incarnata/D. maculata polyploid complex. Molecular data obtained during the last decade have given a better understanding of evolutionary patterns in this complex and explain why it is taxonomically difficult. The data reveal that allotetraploids have been formed repeatedly by hybridization between the same pair of broadly defined parental species, D. incarnata s.lat. and D. maculata s.lat. Some of the widespread allotetraploids are themselves variable and may each consist of several independently derived allotetraploid lineages, or else may have obtained increased levels of diversity by backcrossing with their parental species or by hybridization with other allotetraploids. Whereas some allotetraploids have wide distribution areas indicating that they should be of relatively high age, other allotetraploids, which may be characterized by odd character combinations, are confined to one or a few populations and may be of recent origins. Because of the intricate variation patterns and the difficulty to subdivide the complex into a series of morphologically discrete species, it is argued that all allotetraploids are best included in a broadly circumscribed D. majalis, at least until additional molecular data regarding taxonomic delimitation have been obtained. Widespread and well-known taxa may be provisionally treated as subspecies.
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| 10. |
- Jacobson, Anders, et al.
(författare)
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Phylogenetic relationships in Alisma (Alismataceae) based on RAPDs, and sequence data from ITS and trnL
- 2007
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Ingår i: Plant Systematics and Evolution. - : Springer Science and Business Media LLC. - 1615-6110 .- 0378-2697. ; 265:1-2, s. 27-44
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Tidskriftsartikel (refereegranskat)abstract
- The phylogeny of Alisma (Alismataceae), a genus of approximately nine species of aquatic plants mainly distributed in the Northern Hemisphere, was reconstructed with parsimony analysis on RAPD data and sequences of the nuclear ITS and chloroplast trnL regions, and with MDS on RAPD data. Separate analyses were performed on each data set. Butomus umbellatus was used as outgroup in the analysis of sequence data, and Luronium and Baldellia in the analyses of RAPD data. Among diploid Alisma, two major groups were found: (i) the gramineum group consisting of A. gramineum and A. wahlenbergii, and (ii) the plantago-aquatica group with A. plantago-aquatica, A. orientale, A. subcordatum, A. juzepczukii and A. "bottnicum". Taxa within the groups were poorly separated. The Baltic endemics A. wahlenbergii, A. juzepczukii and A. "bottnicum" have probably originated relatively recently from local populations of A. gramineum (i.e. A. wahlenbergii) and A. plantago-aquatica (i.e. A. juzepczukii and A. "bottnicum"). The exact origin of the polyploid taxa, i.e. A. lanceolatum, A. triviale, A. canaliculatum and A. rariflorum, is still unclear.
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