| 1. |
- Aagaard, Sunniva M.D. 1977-, et al.
(författare)
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Homoploid hybridization in Central European Diphasiastrum (Lycopodiaceae).
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Three species of homoploid hybrid origin are commonly recognized among Central European Diphasiastrum, and reticulate evolutionary events have for a long time been acknowledged as an important factor contributing to the species count in the genus. Presented evidence obtained from molecular data has until recently been scarce and inconclusive. Recent studies have, however, documented reticulate phylogenetic patterns involving all putative parental combinations reported from Central Europe. Reciprocal crosses involving the same parental combinations have also been confirmed. In order to further explore these putative reticulate events, admixture analyses using a Bayesian approach as implemented in the program NewHybrids are conducted on an expanded dataset obtained from six Central European populations from where putative hybrid taxa are reported. A majority of the accessions included in the analyses were inferred to represent pure bred D. alpinum, D. complanatum, D. tristachyum, F1 hybrids, F2 hybrids or backcrosses with one of the parent species. Accessions displaying ambiguous classification were found in both allopatric parent populations as well as in Central European hybrid populations. Presented results indicate the presence of frequently occurring hybrid zones with first and second generation hybrids as well as backcrosses.
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| 2. |
- Aagaard, Sunniva M. D., 1977-, et al.
(författare)
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Occurrence and evolutionary origins of polyploids in the club moss genus Diphasiastrum (Lycopodiaceae)
- 2009
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 52:3, s. 746-754
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Tidskriftsartikel (refereegranskat)abstract
- Two polyploid taxa are commonly recognized in the genus Diphasiastrum, D. wightianum from Asia and D. zanclophyllum from South Africa and Madagascar. Here we present results from Feulgen DNA image densitometry analyses providing the first evidence for the polyploid origin of D. zanclophyllum. Reported for the first time is also data confirming that D. multispicatum and D. veitchii, representing putative parent lineages for D. wightianum, are diploids. Phylogenetic analyses of nuclear regions RPB2, LEAFY and LAMB4 reveal that putative tetraploid accessions are of allopolyploid origin. Diphasiastrum zanclophyllum shows close relationships to the North American taxon D. digitatum on the maternal side, but the paternal relationship is less clear. Two accessions from Asia, both found to be polyploid, have D. veitchii as maternal parent, whereas the paternal paralogs show relationships to D. multispicatum and D. tristachyum, respectively. None of these parental combinations have previously been hypothesized.
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| 3. |
- Aagaard, Sunniva M.D. 1977-, et al.
(författare)
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Resolving maternal relationships in the clubmoss genus Diphasiastrum (Lycopodiaceae)
- 2009
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Ingår i: Taxon. - 0040-0262 .- 1996-8175. ; 58:3, s. 835-848
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Tidskriftsartikel (refereegranskat)abstract
- Diphasiastrum comprises 20-30 species. In addition to a number of species with a circumboreal distribution, several island endemics and putative diploid hybrid species contribute to the diversity of the group. To assess the integrity and relationships of the recognized species, a global phylogeny of Diphasiastrum is constructed using five chloroplast regions comprising ~9000 bp. Six monophyletic groups are identified. Accessions identified as hybrid species cluster in all but one case together with one of its putative parents. Two microsatellite loci are identified, and allelic information combined with sequence information is found diagnostic for the three putative parental taxa in the Central Europe hybrid complexes. Haplotype screening is performed on six Central European populations, from where one or more putative diploid hybrid species have been reported to grow in sympatry with their parent species. The most common parental haplotypes are identified in all populations. Additional intraspecific variation, restricted to single populations, is identified in all sympatric populations at very low frequencies. Taking the low degree of sequence and microsatellite variation into consideration, the acknowledged morphological diversity in Central Europe is probably best explained by phenotypic plasticity, ancestral polymorphisms or relatively recent events of reticulate evolution.
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| 4. |
- Aagaard, Sunniva M.D. 1977-, et al.
(författare)
-
Reticulate phylogenetic patterns in diploid European Diphasiastrum (Lycopodiaceae).
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In Central Europe, three species belonging to Diphasiastrum are considered to be of homoploid hybrid origin. Diphasiastrum issleri is suggested to have originated from a cross between D. alpinum and D. complanatum, D. oellgaardii from D. alpinum and D. tristachyum, and D. zeilleri from D. complanatum and D. tristachyum. Variation at three nuclear regions and two chloroplast microsatellites verify the presence of all three putative parental combinations in Europe. Data obtained with Feulgen DNA image densitometry confirms that all specimens displaying such pattern are diploid. Also, two of three parental combinations have probably arisen repeatedly, implied by the occurrence of chloroplast haplotypes associated with different parents. The presented dataset cannot be used as argument for the existence of independent evolutionary entities hybrid origin. This is nonetheless an important first step in order to address the influence of reticulate evolutionary events in European Diphasiastrum.
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| 5. |
- Thulin, Mats, 1948-, et al.
(författare)
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Revised lectotypification of Lycopodium complanatum L. (Lycopodiaceae)
- 2009
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Ingår i: Taxon. - 0040-0262 .- 1996-8175. ; 58:3, s. 974-976
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Tidskriftsartikel (refereegranskat)abstract
- The currently accepted lectotype of the circumboreal species Lycopodium complanatum L., or Diphasiastrum complanatum (L.) Holub, is a specimen of the related species L. tristachyum Pursh, or D. tristachyum (Pursh) Holub, mainly distributed in eastern North America and Europe. This lectotype, in LINN, is here superseded in favour of an alternative original element in the Celsius herbarium in Uppsala, supported by an epitype, on the grounds of conflict with the protologue. Thereby the traditional usage of the well-known name L. complanatum can be maintained.
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