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| 2. |
- Bisang, Irene, et al.
(författare)
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Can the meiotic sex ratio explain the sex ratio bias in adult populations in the dioicous moss Drepanocladus lycopodioides?
- 2017
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Ingår i: Journal of Bryology. - : Informa UK Limited. - 0373-6687 .- 1743-2820. ; 39:2, s. 115-120
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Tidskriftsartikel (refereegranskat)abstract
- Sex ratio variation is commonly observed in natural populations of many organisms with separate sexes and genetic sex determination, including bryophytes. Most bryophyte populations exhibit female-skewed expressed adult sex ratios, generally inferred from counts of sexually mature plants. For the rarely sexually reproducing perennial dioicous moss Drepanocladus lycopodioides, we showed that a female bias also exists in the genetic adult sex ratio, using a specifically designed molecular sex-associated marker. Here, we investigated whether the meiotic spore sex ratio contributes to the observed bias in genetic adult sex ratio in natural populations. Earlier attempts to study meiotic sex ratios have involved commonly cultivated ruderals that rapidly express sex in the laboratory. We established single-spore cultures from field-collected sporophytes from these populations and used the marker to assess the sex of individual sporelings. Spore germinability was (near) complete, and mortality among sporelings was virtually absent. The true meiotic sex ratio did not differ from equality, but strongly differed both from the observed genetic sex ratios in the natural adult populations, and from the European scale genetic sex ratio. We conclude that the biased population sex ratios in this species arise at life cycle stages after spore germination. Sexual dimorphism may selectively favour female proliferation during some phase of gametophyte development. Based on methodological progress, we successfully used a perennial study species with rare sexual reproduction, which significantly broadens the life history spectrum investigated in bryophyte sex ratio studies.
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| 4. |
- Bu, Zhaojun, et al.
(författare)
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Performance of four mosses in a reciprocal transplant experiment : implications for peatland succession in NE China
- 2013
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Ingår i: Journal of Bryology. - 0373-6687 .- 1743-2820. ; 35, s. 220-227
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Tidskriftsartikel (refereegranskat)abstract
- Sphagnum dominates the moss layer in northern peatlands, but its dominance has decreased while there has been an expansion of other moss genera in some peatlands of NE China since the 1960s. To discover the mechanisms underlying this succession, we performed a four-month reciprocal transplant experiment in Hani Peatland with three Sphagnum species, Sphagnum palustre, S. magellanicum, and S. fuscum and one other moss Polytrichum strictum. Performance of the four mosses and the environmental factors: height above water table (HWT), vascular plant cover and pH, electrical conductivity, base cations, and N and P concentrations in water in the four moss habitats were measured. Biomass production in S. palustre was negatively affected by HWT. Phosphorus had a positive effect on biomass production in S. magellanicum and Polytrichum. None of the environmental factors had any effect on S. fuscum. Overall, the three Sphagnum species deteriorated in P. strictum hummocks, while P. strictum exhibited a wider ecological amplitude and maintained or increased its vigour levels in Sphagnum hummocks. Biomass production in S. palustre and S. magellanicum was negatively affected by P. strictum indicating the competitive ability of P. strictum. Our results suggest that its wide ecological amplitude and competitive ability may explain why P. strictum can expand and replace Sphagnum in some northern peatlands.
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- Callaghan, D. A., et al.
(författare)
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Geographic range and population size of the habitat specialist Codonoblepharon forsteri in a changing climate
- 2022
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Ingår i: Journal of Bryology. - 0373-6687 .- 1743-2820. ; 44:1, s. 35-40
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Codonoblepharon forsteri is a rare epiphytic moss characteristically associated with water-filled holes in trees. This study aims to review its range and population and assess effects of climate change.Methods: An inventory of sites from where C. forsteri has been recorded was compiled. Extent of Occurrence (EOO) and Area of Occupancy (AOO) were calculated. Population size was estimated, using an occupied tree as an ‘individual-equivalent’ of the moss. Climatic conditions of its current distribution were characterised, and an ensemble model of its distribution generated. The latter was projected onto present and future climatic layers.Results: C. forsteri has been recorded from 205 sites in 18 countries, in Europe, N Africa and SW Asia. It has been undergoing an overall decline. Most sites have few occupied trees, and a world population of 1000–10,000 individual-equivalents is estimated. Model projections suggest the species will experience a range increase of +0.27–0.78 by 2050 and +0.34–0.97 by 2070, especially in the NW, in particular across France and the UK. Range loss is predicted to be -0.16–0.23 in 2050 and -0.18–0.32 in 2070, affecting the driest areas of the current range around the Mediterranean, especially in N Africa.Conclusions: C. forsteri has a relatively large EOO but a relatively small AOO, likely the product of its habitat specialism. A major reason for recent declines appears to be widespread abandonment of traditional ‘pollarding’ of trees. The potential climatic range of the species will shift significantly northwards over the next few decades
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| 6. |
- Campbell, Charles, 1982-, et al.
(författare)
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The effects of winter stress on Sphagnum specieswith contrasting macro- and microdistributions
- 2019
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Ingår i: Journal of Bryology. - : Taylor & Francis. - 0373-6687 .- 1743-2820. ; 41:3, s. 205-217
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Sphagnum L. forms much of the ground cover in northern peatlands. Different species show affinities for bioclimatic regions in Europe (oceanic/continental; northern/southern) and species-specific tolerance of winter conditions can be a factor explaining their distribution.Methods: We focussed on low temperature in a series of experiments and tested (1) the innate ability of a selection of Sphagnum species to tolerate low temperature in relation to their micro-topographic (wetness) and geographical (climate) distribution; (2) the rate of cold tolerance acquisition; and (3) the ability of species to survive a range of low temperature once cold hardened.Key results: Our experiments showed that maximal PSII efficiency (Fv/Fm, chlorophyll fluorescence), growth rates and survival were all negatively affected by sub-zero temperatures. Environmental conditions associated with the onset of winter (colder nights and shorter days) triggered the acquisition of cold tolerance in Sphagnum.Conclusions: The results were not unequivocal, but species associated with colder climates were generally more tolerant of sub-zero conditions. Species associated with the wettest and driest ends of the wetness gradient were more consistent in their responses than those in between, with wetter-dwelling species being less sensitive to sub-zero temperature than species found in drier microhabitats. Overall, our results suggest that adaptation to winter conditions contribute to the current distribution patterns of Sphagnum species.
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| 7. |
- Cronberg, Nils, et al.
(författare)
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Clonal distribution, fertility and sex ratios of the moss Plagiomnium affine (Bland.) T.Kop. in forests of contrasting age
- 2003
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Ingår i: Journal of Bryology. - : Informa UK Limited. - 1743-2820 .- 0373-6687. ; 25, s. 155-162
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Tidskriftsartikel (refereegranskat)abstract
- Six populations of the clonal forest floor moss Plagiomnium affine from forests of different age were screened for genetic variation at 23 allozyme loci, of which nine were polymorphic. Samples consisting of two adjacent unconnected shoots were taken at regular intervals along one transect from each population. A total of 602 shoots was analysed. Almost 80% of the shoots were sterile (i.e. not expressing male or female gender). Sex remained unknown for only 10% of shoots after identification of genets based on electrophoretic data. We identified a mean number of 3.7 fertile clones per population. The mean length of clones along transects in each population ranged between 2 and 3 in. The size distribution within populations was bimodal, with a few dominant clones and a varying number of much smaller clones. The overall sex ratio was slightly female biased at the ramet level, but balanced at the genet level. Forest age was negatively correlated with percentage of sterile shoots and positively correlated with frequency of sporophytes. In both cases correlations were significant only if population 1, which was subject to extreme soil disturbance by badgers, was excluded. We conclude that the effective population size is larger, and the susceptibility to genetic drift is lower, in old forests.
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