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  • 1. Armbruster, W. Scott
    et al.
    Hansen, Thomas F.
    Pélabon, Christophe
    Pérez-Barrales, Rocio
    Maad, Johanne
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    The adaptive accuracy of flowers: measurement and microevolutionary patterns2009In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 103, no 9, p. 1529-1545Article in journal (Refereed)
  • 2.
    Boberg, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Alexandersson, Ronny
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Jonsson, Magdalena
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Maad, Johanne
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Nilsson, Anders L.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Pollinator shifts and the evolution of spur length in the moth-pollinated orchid Platanthera bifolia2014In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 113, no 2, p. 267-275Article in journal (Refereed)
    Abstract [en]

    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.

  • 3.
    Chapurlat, Elodie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Anderson, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Friberg, Magne
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Sletvold, Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Diel pattern of floral scent emission matches the relative importance of diurnal and nocturnal pollinators in populations of Gymnadenia conopsea2018In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 121, p. 711-721Article in journal (Refereed)
    Abstract [en]

    Background and Aims

    Floral scent is considered an integral component of pollination syndromes, and its composition and timing of emission are thus expected to match the main pollinator type and time of activity. While floral scent differences among plant species with different pollination systems can be striking, studies on intraspecific variation are sparse, which limits our understanding of the role of pollinators in driving scent divergence.

    Methods

    Here, we used dynamic headspace sampling to quantify floral scent emission and composition during the day and at night in the natural habitat of six Scandinavian populations of the fragrant orchid Gymnadenia conopsea. We tested whether diel scent emission and composition match pollinator type by comparing four populations in southern Sweden, where nocturnal pollinators are more important for plant reproductive success than are diurnal pollinators, with two populations in central Norway, where the opposite is true. To determine to what extent scent patterns quantified in the field reflected plasticity, we also measured scent emission in a common growth chamber environment.

    Key Results

    Both scent composition and emission rates differed markedly between day and night, but only the latter varied significantly among populations. The increase in scent emission rate at night was considerably stronger in the Swedish populations compared with the Norwegian populations. These patterns persisted when plants were transferred to a common environment, suggesting a genetic underpinning of the scent variation.

    Conclusions

    The results are consistent with a scenario where spatial variation in relative importance of nocturnal and diurnal pollinators has resulted in selection for different scent emission rhythms. Our study highlights the importance of adding a characterization of diel variation of scent emission rates to comparative studies of floral scent, which so far have often focused on scent composition only.

  • 4.
    Ellis, Tom J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. IST Austria, Campus 1, A-3400 Klosterneuburg, Austria..
    Field, David L.
    IST Austria, Campus 1, A-3400 Klosterneuburg, Austria..
    Repeated gains in yellow and anthocyanin pigmentation in flower colour transitions in the Antirrhineae2016In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 117, no 7, p. 1133-1140Article in journal (Refereed)
    Abstract [en]

    Background and aims Angiosperms display remarkable diversity in flower colour, implying that transitions between pigmentation phenotypes must have been common. Despite progress in understanding transitions between anthocyanin (blue, purple, pink or red) and unpigmented (white) flowers, little is known about the evolutionary patterns of flower-colour transitions in lineages with both yellow and anthocyanin-pigmented flowers. This study investigates the relative rates of evolutionary transitions between different combinations of yellow- and anthocyanin-pigmentation phenotypes in the tribe Antirrhineae. Methods We surveyed taxonomic literature for data on anthocyanin and yellow floral pigmentation for 369 species across the tribe. We then reconstructed the phylogeny of 169 taxa and used phylogenetic comparative methods to estimate transition rates among pigmentation phenotypes across the phylogeny. Key Results In contrast to previous studies we found a bias towards transitions involving a gain in pigmentation, although transitions to phenotypes with both anthocyanin and yellow taxa are nevertheless extremely rare. Despite the dominance of yellow and anthocyanin-pigmented taxa, transitions between these phenotypes are constrained to move through a white intermediate stage, whereas transitions to double-pigmentation are very rare. The most abundant transitions are between anthocyanin-pigmented and unpigmented flowers, and similarly the most abundant polymorphic taxa were those with anthocyanin-pigmented and unpigmented flowers. Conclusions Our findings show that pigment evolution is limited by the presence of other floral pigments. This interaction between anthocyanin and yellow pigments constrains the breadth of potential floral diversity observed in nature. In particular, they suggest that selection has repeatedly acted to promote the spread of single-pigmented phenotypes across the Antirrhineae phylogeny. Furthermore, the correlation between transition rates and polymorphism suggests that the forces causing and maintaining variance in the short term reflect evolutionary processes on longer time scales.

  • 5.
    Fiz-Palacios, Omar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organism Biology, Systematic Biology.
    Vargas, Pablo
    Vila, Roger
    Papadopulos, Alexander S. T.
    Aldasoro, Juan José
    The uneven phylogeny and biogeography of Erodium (Geraniaceae): radiations in the Mediterranean and recent recurrent intercontinental colonization2010In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 106, no 6, p. 871-884Article in journal (Refereed)
    Abstract [en]

    Background and Aims: The genus Erodium is a common feature of Mediterranean-type climates throughout the world, but the Mediterranean Basin has significantly higher diversity than other areas. The aim here is to reveal the biogeographical history of the genus and the causes behind the evolution of the uneven distribution. Methods Seventy-eight new nrITS sequences were incorporated with existing plastid data to explore the phylogenetic relationships and biogeography of Erodium using several reconstruction methods. Divergence times for major clades were calculated and contrasted with other previously published information. Furthermore, topological and temporal diversification rate shift analyses were employed using these data. Key Results Phylogenetic relationships among species are widely congruent with previous plastid reconstructions, which refute the classical taxonomical classification. Biogeographical reconstructions point to Asia as the ancestral area of Erodium, arising approx. 18 MYA. Four incidences of intercontinental dispersal from the Mediterranean Basin to similar climates are demonstrated. Increases in diversification were present in two independent Erodium lineages concurrently. Two bursts of diversification (3 MYA and 0·69 MYA) were detected only in the Mediterranean flora.Conclusions Two lineages diverged early in the evolution of the genus Erodium: (1) subgenus Erodium plus subgenus Barbata subsection Absinthioidea and (2) the remainder of subgenus Barbata. Dispersal across major water bodies, although uncommon, has had a major influence on the distribution of this genus and is likely to have played as significant role as in other, more easily dispersed, genera. Establishment of Mediterranean climates has facilitated the spread of the genus and been crucial in its diversification. Two, independent, rapid radiations in response to the onset of drought and glacial climate change indicate putative adaptive radiations in the genus.

  • 6.
    Friberg, Magne
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Schwind, Christopher
    Raguso, Robert A.
    Thompson, John N.
    Extreme divergence in floral scent among woodland star species (Lithophragma spp.) pollinated by floral parasites2013In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 111, no 4, p. 539-550Article in journal (Refereed)
    Abstract [en]

    A current challenge in coevolutionary biology is to understand how suites of traits vary as coevolving lineages diverge. Floral scent is often a complex, variable trait that attracts a suite of generalized pollinators, but may be highly specific in plants specialized on attracting coevolved pollinating floral parasites. In this study, floral scent variation was investigated in four species of woodland stars (Lithophragma spp.) that share the same major pollinator (the moth Greya politella, a floral parasite). Three specific hypotheses were tested: (1) sharing the same specific major pollinator favours conservation of floral scent among close relatives; (2) selection favours private channels of rare compounds particularly aimed at the specialist pollinator; or (3) selection from rare, less-specialized co-pollinators mitigates the conservation of floral scent and occurrence of private channels. Dynamic headspace sampling and solid-phase microextraction were applied to greenhouse-grown plants from a common garden as well as to field samples from natural populations in a series of experiments aiming to disentangle the genetic and environmental basis of floral scent variation. Striking floral scent divergence was discovered among species. Only one of 69 compounds was shared among all four species. Scent variation was largely genetically based, because it was consistent across field and greenhouse treatments, and was not affected by visits from the pollinating floral parasite. The strong divergence in floral scents among Lithophragma species contrasts with the pattern of conserved floral scent composition found in other plant genera involved in mutualisms with pollinating floral parasites. Unlike some of these other obligate pollination mutualisms, Lithophragma plants in some populations are occasionally visited by generalist pollinators from other insect taxa. This additional complexity may contribute to the diversification in floral scent found among the Lithophragma species pollinated by Greya moths.

  • 7.
    Friberg, Magne
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Waters, Mia T.
    Univ Calif Santa Cruz, Dept Ecol & Evolutionary Biol, Santa Cruz, CA 95064 USA..
    Thompson, John N.
    Univ Calif Santa Cruz, Dept Ecol & Evolutionary Biol, Santa Cruz, CA 95064 USA..
    Nutrient availability affects floral scent much less than other floral and vegetative traits in Lithophragma bolanderi2017In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 120, no 3, p. 471-478Article in journal (Refereed)
    Abstract [en]

    Background and Aims: Many plant-pollinator interactions are mediated by floral scents that can vary among species, among populations within species and even among individuals within populations. This variation could be innate and unaffected by the environment, but, because many floral volatiles have amino-acid precursors, scent variation also could be affected by differences in nutrient availability among environments. In plants that have coevolved with specific pollinators, natural selection is likely to favour low phenotypic plasticity in floral scent even under different conditions of nutrient availability if particular scents or scent combinations are important for attracting local pollinators.

    Methods: Clonal pairs of multiple seed-families of two Lithophragma bolanderi (Saxifragaceae) populations were subjected to a high and a low nutrient treatment. These plants are pollinated primarily by host-specific Greya moths. It was evaluated how nutrient treatment affected variation in floral scent relative to other vegetative and reproductive traits.

    Key Results: Floral scent strength (the per-flower emission rate) and composition were unaffected by nutrient treatment, but low-nutrient plants produced fewer and lighter leaves, fewer scapes and fewer flowers than highnutrient plants. The results held in both populations, which differed greatly in the number and composition of floral scents produced.

    Conclusions: The results reveal a strong genetic component both to scent composition and emission level, and partly contrasts with the only previous study that has assessed the susceptibility of floral volatile signals to variation in the abundance of nutrients. These results, and the tight coevolutionary relationship between Lithophragma plants and their specialized Greya moth pollinators, indicate that reproductive traits important to coevolving interactions, such as the floral scent of L. bolanderi, may be locally specialized and more canalized than other traits important for plant fitness.

  • 8. Lankinen, Asa
    et al.
    Maad, Johanne
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Ecological Botany.
    Armbruster, W. Scott
    Pollen-tube growth rates in Collinsia heterophylla (Plantaginaceae): one-donor crosses reveal heritability but no effect on sporophytic-offspring fitness2009In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 103, no 6, p. 941-950Article in journal (Refereed)
    Abstract [en]

    Evolutionary change in response to natural selection will occur only if a trait confers a selective advantage and there is heritable variation. Positive connections between pollen traits and fitness have been found, but few studies of heritability have been conducted, and they have yielded conflicting results. To understand better the evolutionary significance of pollen competition and its potential role in sexual selection, the heritability of pollen tube-growth rate and the relationship between this trait and sporophytic offspring fitness were investigated in Collinsia heterophylla. Because the question being asked was if female function benefited from obtaining genetically superior fathers by enhancing pollen competition, one-donor (per flower) crosses were used in order to exclude confounding effects of post-fertilization competition/allocation caused by multiple paternity. Each recipient plant was crossed with an average of five pollen donors. Pollen-tube growth rate and sporophytic traits were measured in both generations. Pollen-tube growth rate in vitro differed among donors, and the differences were correlated with in vivo growth rate averaged over two to four maternal plants. Pollen-tube growth rate showed significant narrow-sense heritability and evolvability in a father-offspring regression. However, this pollen trait did not correlate significantly with sporophytic-offspring fitness. These results suggest that pollen-tube growth rate can respond to selection via male function. The data presented here do not provide any support for the hypothesis that intense pollen competition enhances maternal plant fitness through increased paternity by higher-quality sporophytic fathers, although this advantage cannot be ruled out. These data are, however, consistent with the hypothesis that pollen competition is itself selectively advantageous, through both male and female function, by reducing the genetic load among successful gametophytic fathers (pollen), and reducing inbreeding depression associated with self-pollination in plants with mix-mating systems.

  • 9.
    Mendoza, Sandra Petrone
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Lascoux, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Glemin, Sylvain
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. Uppsala University, Science for Life Laboratory, SciLifeLab. Univ Montpellier, Inst Sci Evolu, CNRS, ISEM,EPHE,IRD,UMR 5554, Montpellier, France.
    Competitive ability of Capsella species with different mating systems and ploidy levels2018In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 121, no 6, p. 1257-1264Article in journal (Refereed)
    Abstract [en]

    Background and Aims

    Capsella is a model genus for studying the transition from outcrossing to selfing, with or without change in ploidy levels. The genomic consequences and changes in reproductive traits (selfing syndrome) associated with these shifts have been studied in depth. However, potential ecological divergence among species of the genus has not been determined. Among ecological traits, competitive ability could be relevant for selfing evolution, as selfing has been shown to be statistically associated with reduced competitiveness in a recent meta-analysis.

    Methods

    We assessed the effect of competition on three Capsella species differing in their mating system and ploidy level. We used an experimental design where fitness related traits were measured in focal individuals with and without competitors.

    Key Results

    The diploid selfer (C. rubella) was most sensitive to competition, whereas the tetraploid selfer (C. bursa-pastoris) performed the best, with the diploid outcrosser (C. grandiflora) being intermediate.

    Conclusions

    These results add to the detailed characterization of Capsella species and highlight the possible roles of ecological context and ploidy in the evolutionary trajectories of selfing species.

  • 10.
    Parachnowitsch, Amy L.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. Univ New Brunswick, Dept Biol, Fredericton, Canada.
    Manson, Jessamyn S
    Univ Virginia, Dept Biol, Charlottesville, VA USA.
    Sletvold, Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. Univ New Brunswick, Dept Biol, Fredericton, Canada.
    Evolutionary ecology of nectar2019In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 123, no 2, p. 247-261Article, review/survey (Refereed)
    Abstract [en]

    Background: Floral nectar is an important determinant of plant–pollinator interactions and an integral component of pollination syndromes, suggesting it is under pollinator-mediated selection. However, compared to floral display traits, we know little about the evolutionary ecology of nectar. Combining a literature review with a meta-analysis approach, we summarize the evidence for heritable variation in nectar traits and link this variation to pollinator response and plant fitness. We further review associations between nectar traits and floral signals and discuss them in the context of honest signalling and targets of selection.

    Scope: Although nectar is strongly influenced by environmental factors, heritable variation in nectar production rate has been documented in several populations (mean h2 = 0.31). Almost nothing is known about heritability of other nectar traits, such as sugar and amino acid concentrations. Only a handful of studies have quantified selection on nectar traits, and few find statistically significant selection. Pollinator responses to nectar traits indicate they may drive selection, but studies tying pollinator preferences to plant fitness are lacking. So far, only one study conclusively identified pollinators as selective agents on a nectar trait, and the role of microbes, herbivores, nectar robbers and abiotic factors in nectar evolution is largely hypothetical. Finally, there is a trend for positive correlations among floral cues and nectar traits, indicating honest signalling of rewards.

    Conclusions: Important progress can be made by studies that quantify current selection on nectar in natural populations, as well as experimental approaches that identify the target traits and selective agents involved. Signal–reward associations suggest that correlational selection may shape evolution of nectar traits, and studies exploring these more complex forms of natural selection are needed. Many questions about nectar evolution remain unanswered, making this a field ripe for future research.

  • 11.
    Postma, Froukje M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Lundemo, Sverre
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution. WWF Norway, Postboks 6784, N-0130 Oslo, Norway..
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Seed dormancy cycling and mortality differ between two locally adapted populations of Arabidopsis thaliana2016In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 117, no 2, p. 249-256Article in journal (Refereed)
    Abstract [en]

    Background and Aims Intraspecific variation in seed bank dynamics should contribute to local adaptation, but is not well studied. The extent to which genetic and environmental factors affect dormancy cycling and seed mortality was investigated in the annual herb Arabidopsis thaliana by conducting a reciprocal seed burial experiment. Methods Seeds from two locally adapted populations (from Italy and Sweden) were buried at both of the sites of origin, and seed mortality and germinability were determined during the following 2 years for initially non-dormant glasshouse-matured seeds and dormant field-matured seeds. Key Results Mean soil temperature was higher at the Italian site compared with the Swedish site throughout the year, and the germination proportions were in general higher for seeds buried in Italy than in Sweden. The rate of secondary dormancy induction of the Italian genotype was faster than that of the Swedish genotype at both sites, while the opposite was true for the rate of dormancy release, at least at the Swedish site. The comparison of nondormant glasshouse seeds with dormant field seeds demonstrated that A. thaliana seeds can adjust their dormancy levels to current environmental conditions, and suggests that maternal environmental conditions have only minor effects on dormancy cycles. At both sites, locally produced seeds had low germinability in the first year compared with the second year, suggesting that a considerable fraction of the seeds would enter the seed bank. In Italy, but not in Sweden, seed mortality increased rapidly during the second year of burial. Conclusions This is the first demonstration of intraspecific genetic differentiation in the annual seed dormancy cycle of any species, and the documented difference is likely to contribute to local adaptation. The results suggest that the contribution of a seed bank to seedling recruitment should vary among environments due to differences in the rate of seed mortality.

  • 12.
    Schwallier, Rachel
    et al.
    Nat Biodivers Ctr, POB 9517, NL-2300 RA Leiden, Netherlands.;Grand Valley State Univ, 1 Campus Dr, Allendale, MI 49401 USA..
    Gravendeel, Barbara
    Nat Biodivers Ctr, POB 9517, NL-2300 RA Leiden, Netherlands.;Leiden Univ, Inst Biol Leiden, Sylviusweg 72, NL-2333 CC Leiden, Netherlands.;Univ Appl Sci Leiden, Zernikedreef 11, NL-2300 AJ Leiden, Netherlands..
    de Boer, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology. Nat Biodivers Ctr, POB 9517, NL-2300 RA Leiden, Netherlands.;Univ Oslo, Nat Hist Museum, POB 1172, N-0318 Oslo, Norway..
    Nylinder, Stephan
    Swedish Museum Nat Hist, Frescativagen 40, S-11418 Stockholm, Sweden..
    van Heuven, Bertie Joan
    Nat Biodivers Ctr, POB 9517, NL-2300 RA Leiden, Netherlands..
    Sieder, Anton
    Univ Vienna, Univ Ring 1, A-1010 Vienna, Austria..
    Sumail, Sukaibin
    Sabah Pk Herbarium, POB 6,Kinabalu Pk, Ranau, Sabah, Malaysia..
    van Vugt, Rogier
    Leiden Univ, Hortus Botanicus, Rapenburg 73, NL-2311 GJ Leiden, Netherlands..
    Lens, Frederic
    Nat Biodivers Ctr, POB 9517, NL-2300 RA Leiden, Netherlands..
    Evolution of wood anatomical characters in Nepenthes and close relatives of Caryophyllales2017In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 119, no 7, p. 1179-1193Article in journal (Refereed)
    Abstract [en]

    Background and Aims Nepenthes attracts wide attention with its spectacularly shaped carnivorous pitchers, cultural value and horticultural curiosity. Despite the plant's iconic fascination, surprisingly little anatomical detail is known about the genus beyond its modified leaf tip traps. Here, the wood anatomical diversity of Nepenthes is explored. This diversity is further assessed with a phylogenetic framework to investigate whether the wood characters within the genus are relevant from an evolutionary or ecological perspective, or rather depend on differences in developmental stages, growth habits, substrates or precipitation. Methods Observations were performed using light microscopy and scanning electron microscopy. Ancestral states of selected wood and pith characters were reconstructed using an existing molecular phylogeny for Nepenthes and a broader Caryophyllales framework. Pairwise comparisons were assessed for possible relationships between wood anatomy and developmental stages, growth habits, substrates and ecology. Key Results Wood anatomy of Nepenthes is diffuse porous, with mainly solitary vessels showing simple, bordered perforation plates and alternate intervessel pits, fibres with distinctly bordered pits (occasionally septate), apotracheal axial parenchyma and co-occurring uni- and multiseriate rays often including silica bodies. Precipitation and growth habit (stem length) are linked with vessel density and multiseriate ray height, while soil type correlates with vessel diameter, vessel element length and maximum ray width. For Caryophyllales as a whole, silica grains, successive cambia and bordered perforation plates are the result of convergent evolution. Peculiar helical sculpturing patterns within various cell types occur uniquely within the insectivorous clade of non-core Caryophyllales. Conclusions The wood anatomical variation in Nepenthes displays variation for some characters dependent on soil type, precipitation and stem length, but is largely conservative. The helical-banded fibre-sclereids that mainly occur idioblastically in pith and cortex are synapomorphic for Nepenthes, while other typical Nepenthes characters evolved convergently in different Caryophyllales lineages.

  • 13.
    Sundberg, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Size matters for violent discharge height and settling speed of Sphagnum spores: important attributes for dispersal potential2010In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 105, no 2, p. 291-300Article in journal (Refereed)
    Abstract [en]

    Initial release height and settling speed of diaspores are biologically controlled components which are key to modelling wind dispersal. Most Sphagnum (peat moss) species have explosive spore liberation. In this study, how capsule and spore sizes affect the height to which spores are propelled were measured, and how spore size and spore number of discharged particles relate to settling speed in the aspherical Sphagnum spores. Spore discharge and spore cloud development were filmed in a closed chamber (nine species). Measurements were taken from snapshots at three stages of cloud development. Settling speed of spores (14 species) and clusters were timed in a glass tube. The maximum discharge speed measured was 3 center dot 6 m s(-1). Spores reached a maximum height of 20 cm (average: 15 cm) above the capsule. The cloud dimensions at all stages were related positively to capsule size (R-2 = 0 center dot 58-0 center dot 65). Thus species with large shoots (because they have large capsules) have a dispersal advantage. Half of the spores were released as singles and the rest as clusters (usually two to four spores). Single spores settled at 0 center dot 84-1 center dot 86 cm s(-1), about 52 % slower than expected for spherical spores with the same diameters. Settling speed displayed a positive curvilinear relationship with spore size, close to predictions by Stokes' law for spherical spores with 68 % of the actual diameters. Light-coloured spores settled slower than dark spores. Settling speed of spore clusters agrees with earlier studies. Effective spore discharge and small, slowly settling spores appear particularly important for species in forested habitats. The spore discharge heights in Sphagnum are among the greatest for small, wind-dispersed propagules. The discharge heights and the slow settling of spores affect dispersal distances positively and may help to explain the wide distribution of most boreal Sphagnum species.

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