| 1. |
- Boberg, Elin, et al.
(författare)
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Despite their apparent integration, spur length but not perianth size affects reproductive success in the moth-pollinated orchid Platanthera bifolia
- 2009
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 23:5, s. 1022-1028
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of many floral traits is thought to have been shaped by pollinator-mediated selection for increased attractiveness or an improved mechanical fit of flowers to pollinators. Yet, few studies have examined experimentally the independent and interactive effects of different aspects of flower morphology on plant reproductive success. In the orchid Platanthera bifolia, perianth size and spur length are positively correlated within and among populations. To test the hypothesis that pollination success and seed output increases with increasing perianth size and spur length, we manipulated the two traits in a factorial design in a long-spurred population of P. bifolia pollinated by long-tongued hawkmoths. Additionally, to determine whether differences in selfing rate can explain variation in fruit set and fruit size, we performed controlled self- and cross-pollination. Plants with long spurs had more flowers pollinated, more pollen removed and produced more and larger fruits compared to plants with short spurs. In contrast, perianth size did not affect the pollination success or fruit production of P. bifolia. Fruit production and fruit size did not differ among flowers pollinated with self- and cross pollen, respectively. This indicates that reduced pollen deposition rather than pollinator-mediated self-pollination caused the reduction in fruit set and fruit volume observed after shortening of the spur. The results demonstrate that spur length, but not perianth size, is critical for reproductive success in P. bifolia, and suggest that among-population differentiation in perianth size may reflect a correlated response to selection on spur length. The results are consistent with the hypothesis that visual display is less important than other cues for the reproductive success of P. bifolia, and underscore the necessity to experimentally examine the functional significance of putatively adaptive traits.
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| 2. |
- Boberg, Elin, 1980-
(författare)
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Evolution of Spur Length in a Moth-pollinated Orchid
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is considerable evidence that pollinator shifts can explain many differences in flower morphology between closely related plant species, but the extent to which pollinator shifts can explain the maintenance of among-population variation in floral traits within species is poorly known. In this thesis, I combined comparative and experimental approaches to examine the evolution of floral traits in the moth-pollinated orchid Platanthera bifolia. More specifically, I investigated (1) the relationship between flower and pollinator morphology, (2) phenotypic selection on morphology and phenology in populations in contrasting environments, (3) components of prezygotic reproductive isolation among divergent populations, and (4) the adaptive and functional significance of two correlated floral traits. A study of Scandinavian of P. bifolia populations revealed that spur length was positively correlated with proboscis length of local pollinators, which suggests that variation in spur length reflects adaptive evolution in response to geographically variable pollinator-mediated selection. A phenotypic selection study on Öland, SE Sweden, suggested that disruptive selection on spur length contributes to the maintenance of a bimodal distribution of spur length in mixed habitats, but provided very limited evidence of divergent selection on plant morphology and flowering phenology in grassland and woodland habitats. Field experiments revealed strong reproductive isolation between divergent populations on Öland, due to differences in spatial distribution, flowering phenology, and pollinators, and among-population incompatibility. The results suggest that prezygotic reproductive isolation contributes to the maintenance of population differentiation in floral traits in P. bifolia. A field manipulation experiment demonstrated that spur length but not perianth size affects pollination success and seed production. This suggests that among-population differentiation in perianth size may be the result of a genetic correlation with spur length. Taken together, the results of this thesis suggest that pollinator-mediated selection can shape the evolution of intraspecific floral variation.
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| 3. |
- Boberg, Elin, 1980-, et al.
(författare)
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Phenotypic selection on floral traits in divergent populations of the moth-pollinated orchid Platanthera bifolia
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Among-population differences in flower morphology is commonly attributed to divergent natural selection mediated by pollinators, but comparisons of current selection in populations growing in contrasting environments are scarce. In the moth-pollinated orchid Platanthera bifolia, floral morphology and flowering phenology differ between grassland and woodland populations on the island Öland, SE Sweden. To examine whether among-population variation in floral morphology is consistent with differences in current selection, we documented phenotypic selection through female and male function on flowering phenology, plant height, flower production and spur length in three populations. One grassland and one woodland population were studied in three years, and one population bimodal for spur length and occurring in a mixed habitat was studied in one year. There was evidence of disruptive selection on spur length in the population in the mixed habitat. In one of three years, there was evidence of divergent selection on plant height between the grassland and woodland population. In all three years selection favoured longer nectar spurs; selection gradients were statistically significant in the short-spurred grassland population, but not in the long-spurred woodland population. In both populations, there was directional selection for earlier flowering and more flowers through female function. Seed production was pollen limited in the grassland population. The results support the hypothesis that disruptive selection through female reproductive success contributes to the maintenance of a bimodal distribution of spur length in P. bifolia in mixed habitats, but provides very limited evidence of divergent selection on plant morphology and flowering phenology in grassland and woodland populations of P. bifolia. The results are discussed in relation to the evolution of floral traits and the challenges associated with detecting stabilizing selection in natural populations.
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| 4. |
- Boberg, Elin, 1980-, et al.
(författare)
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Pollinator shifts and the evolution of spur length in the moth-pollinated orchid Platanthera bifolia
- 2014
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 113:2, s. 267-275
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Tidskriftsartikel (refereegranskat)abstract
- Plantpollinator interactions are thought to have shaped much of floral evolution. Yet the relative importance of pollinator shifts and coevolutionary interactions for among-population variation in floral traits in animal-pollinated species is poorly known. This study examined the adaptive significance of spur length in the moth-pollinated orchid Platanthera bifolia. Geographical variation in the length of the floral spur of P. bifolia was documented in relation to variation in the pollinator fauna across Scandinavia, and a reciprocal translocation experiment was conducted in south-east Sweden between a long-spurred woodland population and a short-spurred grassland population. Spur length and pollinator fauna varied among regions and habitats, and spur length was positively correlated with the proboscis length of local pollinators. In the reciprocal translocation experiment, long-spurred woodland plants had higher pollination success than short-spurred grassland plants at the woodland site, while no significant difference was observed at the grassland site. The results are consistent with the hypothesis that optimal floral phenotype varies with the morphology of the local pollinators, and that the evolution of spur length in P. bifolia has been largely driven by pollinator shifts.
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| 5. |
- Boberg, Elin, 1980-, et al.
(författare)
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Reproductive isolation among divergent populations of the moth-pollinated orchid Platanthera bifolia
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Differentiation in floral traits has been documented between populations in contrasting habitats in several species of flowering plants, but few studies have investigated whether barriers to reproduction contribute to the maintenance of this variation. We investigated components of prezygotic reproductive isolation between short-spurred and long-spurred populations of the moth-pollinated orchid Platanthera bifolia on the island of Öland, SE Sweden. Short-spurred and long-spurred populations were reproductively isolated due to spatial isolation, and differences in flowering time, pollinator morphology and behaviour. The index of reproductive isolation due to pollinators and flowering time was higher for the early-flowering long-spurred plants than it was for the late-flowering short-spurred plants. In addition, we documented a postpollination isolation mechanism manifested as reduced fruit formation in short-spurred plants when pollinated with pollen from long-spurred plants. The results indicate that strong reproductive isolation contribute to the maintenance of population differentiation in morphology and phenology between long-spurred and short-spurred populations of P. bifolia.
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| 6. |
- Faresjö, Tomas, et al.
(författare)
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Swedish nursing and medical students high vaccination adherence during the influenza A (H1N1) pandemic 2009 : Insights for pandemic preparedness
- 2012
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa Healthcare. - 0036-5548 .- 1651-1980. ; 44:3, s. 237-241
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to analyze Swedish health science student decision-making regarding vaccination against pandemic influenza during a national mass vaccination campaign. A questionnaire was distributed to 430 students during the influenza A (H1N1) pandemic in 2009. The data from medical and nursing students were compared and a multiple logistic regression model was applied to identify items independently associated with the decision to be vaccinated. The overall survey response rate was 90%. More medical (93.2%) than nursing students (84.8%) reported that they had received the vaccine (p andlt; 0.01). Only the perception that benefits can outweigh possible side effects was significantly (p andlt; 0.001) associated with the decision to get vaccinated. We recommend that, during pandemics, health science universities focus vaccination information for students on objective risk communication. It should be taken into account that the pandemic information provided by authorities to the general public also affects health care students.
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