| 1. |
- Abeli, Thomas, et al.
(författare)
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Geographical pattern in the response of the arctic-alpine Silene suecica (Cariophyllaceae) to the interaction between water availability and photoperiod
- 2015
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Ingår i: Ecological research. - : Wiley. - 0912-3814 .- 1440-1703. ; 30:2, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- We hypothesized a geographical pattern of the plant performance (seedling development, biomass production, relative water content and chlorophyll content) as a result of response to the interaction between photoperiod and water availability in populations of the arctic-alpine Silene suecica from different latitudes, thus experiencing different photoperiods during the growing season. Particularly, we expected a lower drought sensitivity in northern compared to southern populations as a consequence of harsher conditions experienced by the northern populations in terms of water availability. The experiment was carried out under common garden conditions, manipulating the water availability (wet and dry) and the photoperiod (21 and 16 h). We found an interaction between photoperiod and water availability on plant height, leaves, growth, biomass and total chlorophyll. However, the photoperiod neither counteracted nor intensified the effect of drought. Plants exposed to drought compensated for decreasing water availability by reducing their shoot growth. Changes in the chlorophyll content and chlorophyll a/b ratio were observed. Northern populations showed a higher basal growth performance and a greater response to the changed water regime (from wet to dry) than the southern populations. Southern populations showed a reduced ability to respond to drought, but their low basal performance may be advantageous under low water availability, avoiding water loss. In contrast, northern populations showed a stronger plastic response that limited the negative effects of reduced water availability. This study highlights the possibility that the plant response to environmental constraints (specifically water availability) may follow a geographical pattern.
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| 2. |
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| 3. |
- Carlsson-Graner, Ulla, et al.
(författare)
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Host resistance and pathogen infectivity in host populations with varying connectivity
- 2015
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 69:4, s. 926-938
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Tidskriftsartikel (refereegranskat)abstract
- Theory predicts that hosts and pathogens will evolve higher resistance and aggressiveness in systems where populations are spatially connected than in situations in which populations are isolated and dispersal is more local. In a large cross-inoculation experiment we surveyed patterns of host resistance and pathogen infectivity in anther-smut diseased Viscaria alpina populations from three contrasting areas where populations range from continuous, through patchy but spatially connected to highly isolated demes. In agreement with theory, isolated populations of V. alpina were more susceptible on average than either patchily distributed or continuous populations. While increased dispersal in connected systems increases disease spread, it may also increase host gene flow and the potential for greater host resistance to evolve. In the Viscaria-Microbotryum system, pathogen infectivity mirrored patterns of host resistance with strains from the isolated populations being the least infective and strains from the more resistant continuous populations being the most infective on average, suggesting that high resistance selects for high infectivity. To our knowledge this study is the first to characterize the impacts of varying spatial connectivity on patterns of host resistance and pathogen infectivity in a natural system.
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| 4. |
- Carlsson-Graner, Ulla, et al.
(författare)
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Patterns of disease and host resistance in spatially structured systems
- 2014
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Ingår i: European journal of plant pathology. - Netherlands : Springer. - 0929-1873 .- 1573-8469. ; 138:3, s. 499-511
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Tidskriftsartikel (refereegranskat)abstract
- We use data from species of the anther-smut fungi and the host plants Lychnis alpina and Silene dioica to show that spatial structuring at different scales can influence patterns of disease and host resistance. Patterns of disease and host resistance were surveyed in an archipelago subject to land-uplift where populations of S. dioica constitute an age-structured metapopulation, and in three contrasting areas within the mainland range of L. alpina, where population distributions range from continuous, through patchy but spatially connected to highly isolated demes. In S. dioica, disease levels depend on the age, size and density of local patches and populations. Disease is most predictably found in larger dense host patches and populations of intermediate age, and more frequently goes extinct in small old populations. The rate of local disease spread is affected by the level of host resistance; S. dioica populations showing an increase in disease over time are more susceptible than populations where the disease has remained at low levels. Among-population variation in resistance is driven by founding events and populations remain differentiated due to limited gene flow between islands. As observed in the L. alpina system, when populations are more connected, a greater fraction of populations have disease present. Results from a simulation model argue that, while increased dispersal in connected systems can increase disease spread, it may also favour selection of host resistance which ultimately reduces disease levels within populations. This could explain the observed lower disease prevalence in L. alpina in regions where populations are more continuous.
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| 5. |
- Carlsson-Granér, Ulla, et al.
(författare)
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Plant disease and islands
- 2009
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Ingår i: Encyclopedia of Islands. - : University of California Press. - 9780520256491 - 0520256492 ; , s. 748-752
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Bokkapitel (refereegranskat)
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| 6. |
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| 7. |
- Carlsson-Granér, Ulla, et al.
(författare)
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The spatial distribution of plant populations, disease dynamics and evolution of resistance
- 2002
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 97:1, s. 97-110
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Tidskriftsartikel (refereegranskat)abstract
- Empirical studies of the interaction between the anther smut fungus Microbotryum violaceum and its host plant Lychnis alpina were combined with modelling approaches to investigate how variation in the spatial distribution of host populations influences disease dynamics and variation in resistance. Patterns of disease incidence and prevalence were surveyed in three contrasting systems of natural L. alpina populations where there is substantial variation in spatial structure, ranging from large continuous populations through to small isolated patches. Disease incidence (fraction of populations where disease was present) was highest in the continuous situation, and lowest in the most isolated populations. The reverse was true for prevalence (fraction of individuals diseased). To better understand the long-term ecological and evolutionary consequences of differences in among population spatial structure, we developed a two-dimensional spatially explicit simulation model in which host-population spacing was modelled by varying the percentage of sites suitable for the host. The general patterns of disease incidence and prevalence generated in the simulations corresponded well with the patterns observed in natural populations of L. alpina and M. violaceum; i.e. the fraction of sites with disease increased while the average disease prevalence in diseased populations decreased when host populations became more connected. One likely explanation for the differences in disease incidence and prevalence seen in natural populations is that the evolution of host resistance varies as a function of the degree of fragmentation. This is supported by simulation results that were qualitatively similar to the survey data when resistance was allowed to vary, but not when hosts were assumed to be uniformly susceptible. In the former, the frequency of resistance increased markedly as host populations became more connected.
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| 8. |
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| 9. |
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| 10. |
- Granberg, Åsa, 1977-
(författare)
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Microbotryum violaceum on Silene dioica : understanding traits that influence plant-pathogen interactions
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dynamics of a plant-pathogen interaction vary both within and among species. Both spatial structuring and specific genetic and life-history characteristics will affect the interaction and the outcome of a potential co-evolution between the two organisms. In this thesis I have studied the interaction between the wild perennial herb Silene dioica and its automictic, obligate anther smut Microbotryum violaceum MvSd. From the plant perspective, I have examined different aspects of biochemical resistance in S. dioica to M. violaceum MvSd. From the pathogen perspective, I have focused on the breeding system of M. violaceum MvSd and its connection to fitness and distribution of genetic diversity. I have used varying methods; glasshouse trails involving inoculation of plants with the pathogen, classical Mendelian analysis involving controlled crosses between plants, microscopic studies of spores and molecular DNA-analysis. With the results I demonstrate that resistance to M. violaceum MvSd in S. dioica can be specific to the attacking pathogen strain and also spatially highly diverse both within and among populations within a metapopulation. Together, these factors are likely to delay the establishment of the disease within host populations and reduce the spread and amount of disease, once it has been established. The results also suggest that the specific resistance expressed against two different M. violaceum MvSd strains were determined by separate gene systems and that, in both cases, the resistance was simply inherited. This implies a potential for relatively rapid response to M. violaceum-induced selection in S. dioica populations variable for resistance. My results also show that automixis clearly is the predominating breeding system of M. violaceum MvSd, similarly to what earlier has been shown for M. violaceum MvSl. Furthermore, I found lower levels of neutral genetic diversity in M. violaceum MvSd in the northern parts of Sweden, compared to what has been found in populations in more southern Europe. This result is consistent with predictions that populations in the outer regions of a species distribution have lower levels of genetic variation. Moreover, populations were highly differentiated in northern Sweden, which could have been generated by high selfing rates, genetic drift and high population turnover rates, all factors that coincide with life-history and ecology of M. violaceum MvSd. However, despite the general low variability in neutral genetic markers, I did find variation in fitness related traits, both within and among populations, as well as differences in infection ability between strains, suggesting there is a potential for co-evolution between S. dioica and M. violaceum MvSd in the area. To summarize, this thesis reflect a plant-pathogen system that is highly influenced by constant colonisation-extinction dynamics, which is likely to have influenced both the genetics of resistance in the plant and the breeding system of the pathogen and thus also the interaction between the two organisms.
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| 11. |
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| 12. |
- Granberg, Åsa, et al.
(författare)
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Variation in breeding system traits within and among populations of Microbotryum violaceum on Silene dioica
- 2008
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Ingår i: International journal of plant sciences. - : University of Chicago Press. - 1058-5893 .- 1537-5315. ; 169:2, s. 293-303
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Tidskriftsartikel (refereegranskat)abstract
- Breeding systems exert profound effects on the amount and distribution of genetic diversity within and among populations. Knowledge of breeding systems is also important for understanding dynamics between coevolving organisms, e.g., pathogen‐host interactions. Here we study the breeding system of the obligate anther smut Microbotryum violaceum on Silene dioica. Microbotryum violaceum is capable of both inbreeding and outcrossing, but several recent studies on other host races have indicated that automixis via intrapromycelial mating is the predominant breeding system. Compared with conjugations between cells from different meioses, automixis results in slower loss of heterozygosity and faster production of infectious hypha. However, high rates of intrapromycelial matings have been suggested to invoke a fitness cost due to production of fewer infectious dikaryons. Working with single strains under standardized laboratory conditions, we studied traits that could influence the distribution of genetic variability and pathogen fitness. We found that intrapromycelial mating is the dominant conjugation form for M. violaceum var. dioica but that the breeding system varies, partly because of genetic differences, both within and among populations. Further, we did not find the predicted fitness reduction for intrapromycelial matings, suggesting that intrapromycelial mating is a highly favorable breeding system for M. violaceum.
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| 13. |
- Mondoni, Andrea, et al.
(författare)
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Seed dormancy and longevity in subarctic and alpine populations of Silene suecica
- 2018
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Ingår i: Alpine Botany. - : Springer. - 1664-2201 .- 1664-221X. ; 128:1, s. 71-81
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Tidskriftsartikel (refereegranskat)abstract
- Despite the strong environmental control of seed dormancy and longevity, their changes along latitudes are poorly understood. The aim of this study was to assess seed dormancy and longevity in different populations across the distribution of the arctic-alpine plant Silene suecica. Seeds of seven populations collected from alpine (Spain, Italy, Scotland) and subarctic (Sweden, Norway) populations were incubated at four temperature regimes and five cold stratification intervals for germination and dormancy testing. Seed longevity was studied by exposing seeds to controlled ageing (45 A degrees C, 60% RH) and regularly sampled for germination. Fresh seeds of S. suecica germinated at warm temperature (20/15 A degrees C) and more in subarctic (80-100%) compared to alpine (20-50%) populations showed a negative correlation with autumn temperature (i.e., post-dispersal period). Seed germination increased after cold stratification in all populations, with different percentages (30-100%). Similarly, there was a large variation of seed longevity (p(50) = 12-32 days), with seeds from the wettest locations showing faster deterioration rate. Subarctic populations of S. suecica were less dormant, showing a warmer suitable temperature range for germination, and a higher germinability than alpine populations. Germination and dormancy were driven by an interplay of geographical and climatic factors, with alpine and warm versus subarctic and cool autumn conditions, eliciting a decrease and an increase of emergence, respectively. Germination and dormancy patterns typically found in alpine habitats may not be found in the arctic.
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| 14. |
- Vass, Máté, et al.
(författare)
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Co-occurrences enhance our understanding of aquatic fungal metacommunity assembly and reveal potential host–parasite interactions
- 2022
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press. - 0168-6496 .- 1574-6941. ; 98:11
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Tidskriftsartikel (refereegranskat)abstract
- Our knowledge of aquatic fungal communities, their assembly, distributions and ecological roles in marine ecosystems is scarce. Hence, we aimed to investigate fungal metacommunities of coastal habitats in a subarctic zone (northern Baltic Sea, Sweden). Using a novel joint species distribution model and network approach, we quantified the importance of biotic associations contributing to the assembly of mycoplankton, further, detected potential biotic interactions between fungi–algae pairs, respectively. Our long-read metabarcoding approach identified 493 fungal taxa, of which a dominant fraction (44.4%) was assigned as early-diverging fungi (i.e. Cryptomycota and Chytridiomycota). Alpha diversity of mycoplankton declined and community compositions changed along inlet–bay–offshore transects. The distributions of most fungi were rather influenced by environmental factors than by spatial drivers, and the influence of biotic associations was pronounced when environmental filtering was weak. We found great number of co-occurrences (120) among the dominant fungal groups, and the 25 associations between fungal and algal OTUs suggested potential host–parasite and/or saprotroph links, supporting a Cryptomycota-based mycoloop pathway. We emphasize that the contribution of biotic associations to mycoplankton assembly are important to consider in future studies as it helps to improve predictions of species distributions in aquatic ecosystems.
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| 15. |
- Vass, Mate, et al.
(författare)
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Microeukaryote community coalescence strengthens community stability and elevates diversity
- 2024
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press. - 0168-6496 .- 1574-6941. ; 100:8
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Tidskriftsartikel (refereegranskat)abstract
- Mixing of entire microbial communities represents a frequent, yet understudied phenomenon. Here, we mimicked estuarine condition in a microcosm experiment by mixing a freshwater river community with a brackish sea community and assessed the effects of both environmental and community coalescences induced by varying mixing processes on microeukaryotic communities. Signs of shifted community composition of coalesced communities towards the sea parent community suggest asymmetrical community coalescence outcome, which, in addition, was generally less impacted by environmental coalescence. Community stability, inferred from community cohesion, differed among river and sea parent communities, and increased following coalescence treatments. Generally, community coalescence increased alpha diversity and promoted competition from the introduction (or emergence) of additional (or rare) species. These competitive interactions in turn had community stabilizing effect as evidenced by the increased proportion of negative cohesion. The fate of microeukaryotes was influenced by mixing ratios and frequencies (i.e. one-time versus repeated coalescence). Namely, diatoms were negatively impacted by coalescence, while fungi, ciliates, and cercozoans were promoted to varying extents, depending on the mixing ratios of the parent communities. Our study suggests that the predictability of coalescence outcomes was greater when the sea parent community dominated the final community, and this predictability was further enhanced when communities collided repeatedly.
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