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| 2. |
- Cronberg, Nils
(författare)
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Absence of genetic variation in populations of the liverwort Plagiochila porelloides from northern Greece and southern Scandinavia
- 2000
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Ingår i: Lindbergia. - 0105-0761. ; 25:1, s. 20-24
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Populations of the leafy liverwort Plagiochila porelloides from lowland southern Scandinavia and mountain peaks on mainland Greece were screened for polymorphisms at 16 putative isozyme loci. The study areas were chosen to represent regions severely and mildly affected by the Pleistocene glaciations, respectively. As in an earlier study from Poland, total absence of variability was recorded. It is concluded that a population ancestral to the present-day populations may have passed through a severe bottleneck. The data are uninformative regarding the circumstances of this event.
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| 3. |
- Cronberg, Nils, et al.
(författare)
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Allelopathy in bryophytes - a review
- 2018
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Ingår i: Lindbergia. - : Dutch Bryological and Lichenological Society and Nordic Bryological Society. - 0105-0761. ; 41, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Allelopathy in bryophytes shapes ecosystems by influencing the species composition of both vascular plants and other bryophytes. Several allelopathically active chemicals in bryophytes have been discovered since the latter half of the 20th century and laboratory studies have showed their inhibiting impact on germination, growth and establishment of surrounding plants. However, other studies failed to demonstrate these effects. In the field, other properties of bryophytes might have stronger impacts, such as mechanical obstruction or alterations in temperature. In laboratory studies, water might not be an adequate extractant for active substances, since all of the chemicals claimed to be allelopathic are lipophilic with potentially longer retention times of the active substances in the soil when compared to water-soluble substances.
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| 4. |
- Cronberg, Nils
(författare)
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Animal-mediated fertilization in bryophytes – parallel or precursor to insect pollination in angiosperms?
- 2012
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Ingår i: Lindbergia. - 0105-0761. ; 35, s. 76-85
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Tidskriftsartikel (refereegranskat)abstract
- Bryophytes have until now been absent from all hypotheses regarding the origin of insect pollination of seed plants. The discovery that both springtails and mites are able to transfer sperm in mosses makes it possible to suggest a ’Bryophyte precursor hypothesis of plant pollination’ stating that animal-mediated fertilization in mosses and insect pollination in seed plants is historically linked by homologous or analogous evolution of structures responsible for attraction and reward aimed at a pool of fertilization vectors originally co-evolved with bryophytes and subsequently co-opted by seed plants. The earliest point in time when animal-mediated fertilization of bryophytes, involving springtails and mites, could have arisen is Late Silurian/Early Devonian, ca 280 Myr before the evolutionary radiation of angiosperms. Soil-dwelling microarthropods and wingless insects are assumed to have been the primary vectors transporting sperm in ancient mosses and possibly other groups of bryophytes. These animals may later have secondarily expanded to transfer pollen in gymnosperms and angiosperms, similar to the frequent pollinator shifts observed among angiosperm groups. Several ancestral traits pointed out by recent studies of early angiosperms are in favour of this hypothesis, such as small size of flowers, small and non-sticky pollen, adaptations for growth in moist and shaded habitats close to running water, and weedy growth forms with rapid life-cycles in disturbed habitats. It is also possible to envisage a link from sexual attractants excreted by oogonia in charophyte algae and archegonia in bryophytes to guide sperm, via sugar released to attract insects in pollination drop mechanisms in gymnosperms to more advanced structures specialized for insect attraction such as nectaries and nectar discs in angiosperms.
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| 5. |
- Cronberg, Nils
(författare)
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Genetic differentiation between populations of the moss Hylocomium splendens from low versus high elevation in the Scandinavian mountain range
- 2004
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Ingår i: Lindbergia. - 0105-0761. ; 29:1, s. 64-72
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Tidskriftsartikel (refereegranskat)abstract
- To test the genetic relationship between alpine and subalpine forms of Hylocomium splendens, pairwise sampling was undertaken of populations from four areas, representing the southern and northern ranges of the Scandes. From each population I sampled 75 shoots in a hierarchical fashion, and these were screened for variation at 12 allozyme loci. The pairwise genetic identity (I) among subalpine and alpine populations was, respectively, 0.970 and 0.972, versus 0.946 between the altitudinal groups. This suggests that populations from subalpine and alpine zones are genetically differentiated. The total gene diversity (HT) based on polymorphic loci was slightly higher for alpine populations (0.330) than for subalpine populations (0.244), whereas the relative differentiation among populations (GST) was lower for alpine populations (0.054) than for subalpine populations (0.080). The number of observed clones was high in all populations, ranging from 18 to 29. Mean number of recorded haplotypes within 10x10 cm patches was higher in alpine populations than in subalpine populations, which in part could be explained by the nearly double ramet density in the former. I conclude that two main genetic variants of Hylocomium splendens, with different climate associations, occur in Scandinavia.
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| 7. |
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| 8. |
- Cronberg, Nils
(författare)
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No difference in isozyme banding patterns between Plagiochila porelloides and P. norvegica
- 2000
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Ingår i: Lindbergia. - 0105-0761. ; 25:1, s. 17-19
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Material of the recently described endemic liverwort Plagiochila norvegica was collected from the type locality in Norway and tested against the widespread P. porelloides for differences in isozyme banding patterns. No difference was found at any of 16 putative loci. A limited sample of P. asplenioides, which was included as an outgroup, differed at five loci.
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| 9. |
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| 10. |
- Darell, Per, et al.
(författare)
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Bryophytes in black alder swamps in south Sweden: habitat classification, environmental factors and life-strategies
- 2011
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Ingår i: Lindbergia. - 0105-0761. ; 34, s. 9-29
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Tidskriftsartikel (refereegranskat)abstract
- A considerable part of black alder swamps in Europe are situated in south Sweden. These swamps are frequently rich in bryophytes, but the variation in species composition is often large between sites. In this study we focus on environmental variables that best predict biodiversity in terms of species number, cover and bryophyte composition. The bryophyte vegetation was analysed in 71 plots of size 10 × 10 m in 31 black alder swamps from south Sweden. A total number of 171 bryophyte species (including 52 liverwort species) were recorded. At plot level the species number ranged between 11 and 54 (0–19 for liverworts and 11–36 for mosses). The black alder swamps were classified into five groups, which turned out to be characterized by a combination of tree species composition and hydrological conditions. 22 environmental and geographic variables were recorded for each plot and used as predictor variables in a redundancy analysis (RDA). These variables explained about 50% of the distribution of bryophytes. The most influential variables along the first axis were slope (positive relationship), basal area of spruce (positive relationship) and basal area of black alder (negative relationship). Along the second axis slope, basal area of ash and water depth had the strongest impact. The variables were subdivided into four groups and analyzed by separate RDAs. The amount of dead wood was important for the species richness in black alder fens in combination with humidity. Epixylic bryophytes tended to occupy spruce dead wood as a primary substrate and alder dead wood as a secondary substrate if spruce is present. Black alder stools were important as substrate for various bryophytes during flooding periods, including Plagiothecium latebricola and some liverworts (Calypogeia spp. and Riccardia spp.). The life-strategy categories were represented by perennial stayers 11%, competitive perennials 28%, stress-tolerant perennials 9%, colonists sensu stricto 21%, pioneer colonists 13%, long-lived shuttles 15% and short-lived shuttles 3%. The composition of life-strategy types varied in the swamps. Stress-tolerant perennials were more common in flat swamps. Colonists were more frequent in swamps with dominance of spruce and in sloping swamps.
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