Louise Lindblom

Genetic variation and population differentiation in the lichen-forming ascomycete Xanthoria parietina on the island Storfosna, central Norway.

Genetic diversity and fine‐scale population structure in the lichen‐forming ascomycete Xanthoria parietina was investigated using sequence variation in part of the intergenic spacer (IGS) and the complete internal transcribed spacer (ITS) regions of the nuclear ribosomal DNA. Sampling included 213 and 225 individuals, respectively, from seven populations in two different habitats, bark and rock, on the island Storfosna off the central west coast of Norway. Both markers revealed significant variation and a total of 10 IGS and 16 ITS haplotypes were found. There were no signs of significant positive spatial autocorrelation at any spatial size class down to 10% of transect length, nor did we find significant deviations from neutrality or signs of historical population expansion. Analysis of molecular variance (amova) indicated that most of the genetic variance observed was within populations, but when populations were grouped according to habitat, more than a quarter of the variance was explained among groups. Pairwise comparisons of populations (FST, exact tests of population differentiation) revealed significant differentiation between populations in different habitats (on bark or rock), but not between populations in the same habitat. Haplotype networks show that internal and presumably old haplotypes are shared between habitats, whereas terminal haplotypes tend to be unique to a habitat, mostly bark. We interpret the observed pattern to mean that there is no evidence of restricted gene flow between populations in the same habitat at the present spatial scale (interpopulation distances one or a few kilometres). On the other hand, differentiation between habitats is considerable, which we attribute to restricted gene flow between habitats (habitat isolation). Evidence suggests that the observed differentiation did not evolve locally. Estimates of divergence time between populations in the respective habitats indicate that an ancestral population started to diverge at least 34 000 years ago but probably much further back in time.

Extended phylogeny and a revised generic classification of the Pannariaceae (Peltigerales, Ascomycota)

Extended phylogeny and a revised generic classification of the Pannariaceae (Peltigerales, Ascomycota)

Community assembly in epiphytic lichens in early stages of colonization

Colonization studies may function as natural experiments and have the potential of addressing important questions about community assembly. We studied colonization for a guild of epiphytic lichens in a former treeless heathland area of 170 km2 in southwest Norway. We investigated if epiphytic lichen species richness and composition on aspen (Populus tremula) trees corresponded to a random draw of lichen individuals from the regional species pool. We compared lichen communities of isolated young (55-120 yr) and old (140-200 yr) forest patches in the heathland area to those of aspen forest in an adjacent reference area that has been forested for a long time. All thalli (lichen bodies) of 32 selected lichen species on trunks of aspen were recorded in 35 aspen sites. When data for each site category (young, old, and reference) were pooled, we found the species richness by rarefaction to be similar for reference sites and old sites, but significantly lower for young sites. The depauperated species richness of young sites was accompanied by a skew in species composition and absence of several species that were common in the reference sites. In contrast, genetic variation screened with neutral microsatellite markers in the lichen species Lobaria pulmonaria showed no significant differences between site categories. Our null hypothesis of a neutral species assembly in young sites corresponding to a random draw from the regional species pool was rejected, whereas an alternative hypothesis based on differences in colonization capacity among species was supported. The results indicate that for the habitat configuration in the heathland area (isolated patches constituting < 0.4% of the area) lichen communities may need a colonization time of 100-150 yr for species richness to level off, but given enough time, isolation will not affect species richness. We suggest that this contradiction to expectations from classical island equilibrium theory results from low extinction rates.

New evidence corroborates population differentiation in Xanthoria parietina

In order to examine genetic variation and population structure of the widespread lichen-forming ascomycete Xanthoria parietina from similar habitats, but different sites in Scandinavia, we investigated seven populations in Scania, southernmost Sweden, and compared the results with a corresponding study on Storfosna, central Norway. Sequence variations of the nuclear ribosomal DNA were used as molecular markers, for both a part of the IGS region and the complete ITS1-5.8S-ITS2 region. The amount of genetic variability observed was comparable in the two investigations. Divergence between populations in different habitats found in the previous study was also present in this study. Xanthoria parietina is genetically differentiated between habitats with no evidence of restricted gene flow between populations in the same habitat at the present spatial scale, at least at sites along the coast of Scandinavia. Differentiation between habitats is considerable at both study sites, which we attribute to restricted gene flow between habitats, i.e. habitat isolation.

Taxonomic revision of Xanthomendoza borealis and Xanthoria mawsonii (Lecanoromycetes, Ascomycota)

The xanthorioid taxa Xanthomendoza borealis and Xanthoria mawsonii are revised using morphological, anatomical, secondary chemical, and molecular characters. We conclude that most specimens determined as X. mawsonii from the Antarctic are conspecific with specimens labelled X. borealis from the Northern Hemisphere. Some specimens named X. mawsonii from the Antarctic are wrongly determined specimens of Xanthoria candelaria (L.) Th. Fr, including the holotype of Xanthoria mawsonii C. W. Dodge. Accordingly, Xanthoria mawsonii C. W. Dodge is a synonym to Xanthoria candelaria (L.) Th. Fr. The only available correct name for the bipolar species, which comprises material previously determined as X. borealis and X. mawsonii, and is distinct from the more widespread taxon X. candelaria ,i sXanthomendoza borealis (R. Sant. & Poelt) Sochting, Karnefelt & S. Kondratyuk.

Molecular evidence supports the distinction between Xanthoria parietina and X. aureola (Teloschistaceae, lichenized Ascomycota)

This study aims to clarify taxonomic relationships within the current concept of Xanthoria parietina in northern Europe. For comparison, X. calcicola was also included in the study. Morphological as well as molecular data were utilized. Morphology indicated the presence of three species, Xanthoria parietina, X. calcicola, and X. aureola, the latter of which is resurrected here from synonymy. The most important separating characters involve colour and thickness of the thallus, lobe width, morphology of laminar structures, and the texture of the upper surface. X. aureola, as recognized here, mostly occurs on seashore rocks. Part of the IGS region as well as the complete ITS were sequenced in 70 individual thalli representing ten geographical regions in Europe. In total, 19 different IGS haplotypes and 20 different ITS haplotypes were present in the data set. Owing to indications of possible recombination between the IGS and the ITS, the two data sets were analyzed separately. Haplotype networks were estimated, both of which indicate that X. parietina is distinct from X. aureola and X. calcicola. In our sample, the two latter do not share haplotypes, but are only separated by a few mutational steps.

Xanthomendoza galericulata, a new sorediate lichen species, with notes on similar species in North America

Abstract The new lichen species Xanthomendoza galericulata L. Lindblom is described from the western United States. It is characterized by helmet-shaped lobe tips, under which soralia are found. Xanthomendoza galericulata is broadly distributed in drier pars of western North America. Information on other small sorediate taxa in the genus, namely X. fulva,X. oregana, and X. weberi (S. Kondr. & Kärnefelt) L. Lindblom comb. nov., is provided as well as a key to all North American sorediate Xanthomendoza species.

Sample size and haplotype richness in population samples of the lichen-forming ascomycete Xanthoria parietina

The fine-scale genetic variation and population structure of lichen-forming fungi is little known and sampling strategies are rarely recommended or discussed. I tested if the sample sizes of molecular data sets used in recent population studies of Xanthoria parietina revealed all haplotypes potentially present and, accordingly, quantified how many haplotypes were potentially missing in the samples. Data sets were concatenated from two geographical regions in Scandinavia and investigated if the sampling reached saturation at two levels: 1) individual-based using rarefaction curves and 2) population-based using species accumulation curves. At both levels, the matrices of two molecular markers (IGS and ITS) were analysed separately. The molecular markers show similar and parallel patterns in all analyses. Rarefaction analyses did not reveal different patterns for populations in different habitats, i.e., bark and rock. Species accumulation curves estimated with the Chao 1 richness estimator indicated that 23% of the IGS and 8% of the ITS haplotypes were not detected. Corresponding figures from an abundance-based coverage estimator (ACE) were 37% and 18%. Pilot studies are recommended to determine appropriate sample sizes for genetic-based population studies of lichen-forming fungi.

Genetic variation in relation to substratum preferences of Hypogymnia physodes

Genetic variability and its relationship to substratum preferences within and among populations of the sorediate foliose lichen Hypogymnia physodes was investigated using sequence variation in the ...

Degelia cyanoloma (Schaer.) H. H. Blom & L. Lindblom comb. et stat. nov ., a distinct species from western Europe

Degelia cyanoloma (Schaer.) H. H. Blom & L. Lindblom is resurrected from synonymy and elevated from varietal rank to species. The taxon was earlier referred to D. plumbea (Lightf.) P. M. Jorg. & P. James, however, several discontinuous character states distinguish the two species. Degelia cyanoloma is characterized morphologically by having a large thallus that is pale greyish when dry, lobes that are composed of consecutive trough-shaped segments with an upper surface without squamules, no isidia or soredia, and apothecia discs that are dark reddish brown to blackish. Degelia cyanoloma has a euoceanic distribution and is known from western Europe (Norway, France, Great Britain, Ireland, Portugal, Spain). Based on results from studies of morphology, we hypothesize that D. atlantica (Degel.) P. M. Jorg. & P. James is the closest relative of D. cyanoloma among the European species of the genus whereas D. plumbea is closely related to D. ligulata P. M. Jorg. & P. James.