| 1. |
- Myllys, L, et al.
(author)
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High cyanobiont selectivity of epiphytic lichens in old growth boreal forest of Finland
- 2007
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In: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 173:3, s. 621-629
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Journal article (peer-reviewed)abstract
- • Here, cyanobiont selectivity of epiphytic lichen species was examined in an old growth forest area in Finland. • Samples of the eight lichen species were collected from the same aspen (Populus tremula) and adjacent aspens in the same stand. The cyanobionts of these samples were compared with free and symbiotic Nostoc obtained from other habitats and geographic regions. • Our results, based on the phylogenetic analysis of a partial small subunit of the ribosomal DNA (16S rDNA) and the rbcLX gene complex did not show any correlation with the geographic origin of the samples at any spatial scale. Instead, there was a correlation between the cyanobionts and the alleged taxonomy of their mycobionts. • The results indicate that the lichen species examined are highly selective towards their cyanobiont partners. Only Lobaria pulmonaria proved to be more flexible, being able to associate with a wide range of Nostoc. A same Nostoc strain was found to form associations with taxonomically unrelated lichens indicating that the cyanobiont–mycobiont associations as a whole were not highly specific in the examined species.
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| 2. |
- Myllys, L, et al.
(author)
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Phylogenetic relationships of Stereocaulaceae based on simultaneous analysis of beta-tubulin, GAPDH and SSU rDNA sequences
- 2005
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In: Taxon. - 0040-0262. ; 54:3, s. 605-618
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Journal article (peer-reviewed)abstract
- The phylogenetic relationships of the lichenised ascomycete family Stereocaulaceae were investigated with partial beta-tubulin, partial glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and SSU rDNA sequence data. Due to the marked length variation in the SSU rDNA sequences, the analyses were performed with direct optimization. The combined analysis of the beta-tubulin, GAPDH and SSU rDNA sequences as well as the separate analyses of beta-tubulin and GAPDH data recognized the monophyletic group comprising Lepraria, Muhria and Stereocaulon. In the combined analysis Stereocaulon tornense appears as a basal taxon in the Stereocaulon clade, suggesting that the crustose growth form and the absence of cephalodia are primitive features within the genus. Muhria is nested in Stereocaulon and groups with the crustose S. cumulatum and S. leucophaeopsis. The genus Lepraria is monophyletic if Leproloma is included, but species that were represented by several specimens in our study, i.e., Lepraria jackii and Leproloma membranaceun, do not appear as monophyletic entities. The genus Pilophorus is included in Cladoniaceae. Combined analysis of the three data-sets clearly led to an increase in support values compared to the separate analyses, showing high support for the monophyly of families Cladoniaceae and Stereocaulaceae and for the sistergroup relation for the two families. The relationships between higher groupings did not reach high support values probably due to the incongruencies among the three datasets.
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| 3. |
- Stenroos, S, et al.
(author)
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High selectivity in symbiotic associations of lichenized ascomycetes and cyanobacteria
- 2006
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In: Cladistics. - 1096-0031. ; 22:3, s. 230-238
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Journal article (peer-reviewed)abstract
- The selectivity of mycobionts and cyanobionts in lichen symbioses were examined. We analyzed symbiotic cyanobionts, collected from different sample sites, and compared them to free-living cyanobacteria Nostoc. Cyanobionts were obtained from lichens assigned to the genera Pseudocyphellaria and Sticta, in particular. Multiple gene loci were screened and direct optimization was used in the phylogenetic analyses. We show that many lichen fungi are strongly selective towards their cyanobionts. Lichenized ascomycetes seem to be able to identify and choose a specific strain, species or a species group of Nostoc with which to associate. The present analyses also suggest that some of the Nostoc taxa may be specialized in symbiotic life with only lichenized ascomycetes. Despite the selectivity observed in fungi, there appears to be no coevolution between the partners. We have also discussed the problems of using the tRNA(Leu) intron as a marker in phylogenetic analyses.
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