| 1. |
- Alatalo, J. M., et al.
(author)
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Effects of ambient climate and three warming treatments on fruit production in an alpine, subarctic meadow community
- 2021
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In: American Journal of Botany. - Oxford : Wiley. - 0002-9122 .- 1537-2197. ; 108:3, s. 411-422
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Journal article (peer-reviewed)abstract
- Premise Climate change is having major impacts on alpine and arctic regions, and inter-annual variations in temperature are likely to increase. How increased climate variability will impact plant reproduction is unclear. Methods In a 4-year study on fruit production by an alpine plant community in northern Sweden, we applied three warming regimes: (1) a static level of warming with open-top chambers (OTC), (2) press warming, a yearly stepwise increase in warming, and (3) pulse warming, a single-year pulse event of higher warming. We analyzed the relationship between fruit production and monthly temperatures during the budding period, fruiting period, and whole fruit production period and the effect of winter and summer precipitation on fruit production. Results Year and treatment had a significant effect on total fruit production by evergreen shrubs, Cassiope tetragona, and Dryas octopetala, with large variations between treatments and years. Year, but not treatment, had a significant effect on deciduous shrubs and graminoids, both of which increased fruit production over the 4 years, while forbs were negatively affected by the press warming, but not by year. Fruit production was influenced by ambient temperature during the previous-year budding period, current-year fruiting period, and whole fruit production period. Minimum and average temperatures were more important than maximum temperature. In general, fruit production was negatively correlated with increased precipitation. Conclusions These results indicate that predicted increased climate variability and increased precipitation due to climate change may affect plant reproductive output and long-term community dynamics in alpine meadow communities.
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| 2. |
- Anderberg, Arne A., et al.
(author)
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Phylogenetic relationships in the order Ericales s.l. : analyses of molecular data from five genes from the plastid and mitochondrial genomes
- 2002
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 89:4, s. 677-687
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Journal article (peer-reviewed)abstract
- Phylogenetic interrelationships in the enlarged order Ericales were investigated by jackknife analysis of a combination of DNA sequences from the plastid genes rbcL, ndhF, atpB, and the mitochondrial genes atp1 and matR. Several well‐supported groups were identified, but neither a combination of all gene sequences nor any one alone fully resolved the relationships between all major clades in Ericales. All investigated families except Theaceae were found to be monophyletic. Four families, Marcgraviaceae, Balsaminaceae, Pellicieraceae, and Tetrameristaceae form a monophyletic group that is the sister of the remaining families. On the next higher level, Fouquieriaceae and Polemoniaceae form a clade that is sister to the majority of families that form a group with eight supported clades between which the interrelationships are unresolved: Theaceae‐Ternstroemioideae with Ficalhoa, Sladenia, and Pentaphylacaceae; Theaceae‐Theoideae; Ebenaceae and Lissocarpaceae; Symplocaceae; Maesaceae, Theophrastaceae, Primulaceae, and Myrsinaceae; Styracaceae and Diapensiaceae; Lecythidaceae and Sapotaceae; Actinidiaceae, Roridulaceae, Sarraceniaceae, Clethraceae, Cyrillaceae, and Ericaceae.
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| 3. |
- Andersson, Stefan
(author)
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Does inbreeding promote evolutionary reduction of flower size? Experimental evidence from Crepis tectorum (Asteraceae).
- 2012
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In: American Journal of Botany. - : Wiley. - 1537-2197 .- 0002-9122. ; 99:8, s. 1388-1398
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Journal article (peer-reviewed)abstract
- • Premise of the study: Small, autogamous flowers have evolved repeatedly in the plant kingdom. While much attention has focused on the mechanisms that promote the shift to autogamy, there is still a paucity of information on the factors that underlie the reduction of flower size so prevalent in selfing lineages. In this study of Crepis tectorum, I examine the role of inbreeding, acting alone or together with selection, in promoting evolutionary reduction of flower size. • Methods: Experimental crosses were performed to produce progeny populations that differed in inbreeding and (or) selection history. Progenies were grown in two different environments and scored for flower size and other characters. • Key results: Inbreeding depressed flower and fruit size, but also caused changes in flowering time and the number of heads produced. Despite some inconsistencies in the results for the last progeny generation, the decline in flower size was persistent over generations, consistent across environments, and similar in magnitude to the effects of selection for small flower size and the floral reduction inferred to have taken place during the shift toward autogamy within the study species. The floral size reduction was largely independent of changes in overall vigor, and there was considerable adaptive potential in flower size (measured by sib analyses and parent-offspring comparisons) after inbreeding. • Conclusions: The results of this study indicate that inbreeding can promote evolutionary reduction of flower size and highlight the close, persistent association between flower and fruit size in the study species.
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| 4. |
- Andersson, Stefan
(author)
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Pollinator and nonpollinator selection on ray morphology in Leucanthemum vulgare (oxeye daisy, Asteraceae)
- 2008
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 95:9, s. 1072-1078
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Journal article (peer-reviewed)abstract
- Despite evidence that both pollinators and nonpollinator agents of selection can shape the evolution of floral characters, there have been few attempts to compare the strengths and directions of selection from pollinators and other agents in the same study system. In this investigation of Leucanthemum vulgare, a self-incompatible composite known for its conspicuous white rays, I obtained data from a ray removal experiment in the field and from a segregating F2 population in an experimental garden to assess the role of pollinator and nonpollinator selection as stabilizing factors on floral evolution in this species. Removal of all rays reduced the pollination success of heads by 31–35%, but did not significantly affect the level of infestation by larvae of the fly Tephritis neesii. Data from F2 plants indicated a potential for indirect selection on ray morphology, mediated through links between ray morphology and measures of vegetative size and plant vigor. The results of this study show that individuals of the normal, rayed phenotype have a clear selective advantage, in terms of both pollinator attraction and general plant vigor. Thus, there were no conflicting selection pressures between the pollinators and the other selective agents considered in this study.
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| 5. |
- Antonelli, Alexandre, 1978, et al.
(author)
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Settling a family feud: a high-level phylogenomic framework for the Gentianales based on 353 nuclear genes and partial plastomes
- 2021
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 108:7, s. 1143-1165
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Journal article (peer-reviewed)abstract
- Premise: Comprising five families that vastly differ in species richness—ranging from Gelsemiaceae with 13 species to the Rubiaceae with 13,775 species—members of the Gentianales are often among the most species-rich and abundant plants in tropical forests. Despite considerable phylogenetic work within particular families and genera, several alternative topologies for family-level relationships within Gentianales have been presented in previous studies. Methods: Here we present a phylogenomic analysis based on nuclear genes targeted by the Angiosperms353 probe set for approximately 150 species, representing all families and approximately 85% of the formally recognized tribes. We were able to retrieve partial plastomes from off-target reads for most taxa and infer phylogenetic trees for comparison with the nuclear-derived trees. Results: We recovered high support for over 80% of all nodes. The plastid and nuclear data are largely in agreement, except for some weakly to moderately supported relationships. We discuss the implications of our results for the order’s classification, highlighting points of increased support for previously uncertain relationships. Rubiaceae is sister to a clade comprising (Gentianaceae + Gelsemiaceae) + (Apocynaceae + Loganiaceae). Conclusions: The higher-level phylogenetic relationships within Gentianales are confidently resolved. In contrast to recent studies, our results support the division of Rubiaceae into two subfamilies: Cinchonoideae and Rubioideae. We do not formally recognize Coptosapelteae and Luculieae within any particular subfamily but treat them as incertae sedis. Our framework paves the way for further work on the phylogenetics, biogeography, morphological evolution, and macroecology of this important group of flowering plants.
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| 6. |
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| 7. |
- Barres, L., et al.
(author)
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RECONSTRUCTING THE EVOLUTION AND BIOGEOGRAPHIC HISTORY OF TRIBE CARDUEAE (COMPOSITAE)
- 2013
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 100:5, s. 867-882
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Journal article (peer-reviewed)abstract
- • Premise of the study: Tribe Cardueae (thistles) forms one of the largest tribes in the family Compositae (2400 species), with representatives in almost every continent. The greatest species richness of Cardueae occurs in the Mediterranean region where it forms an important element of its flora. New fossil evidence and a nearly resolved phylogeny of Cardueae are used here to reconstruct the spatiotemporal evolution of this group. • Methods: We performed maximum parsimony and Bayesian phylogenetic inference based on nuclear ribosomal DNA and chloroplast DNA markers. Divergence times and ancestral area reconstructions for main lineages were estimated using penalized likelihood and dispersal–vicariance analyses, respectively, and integrated over the posterior distribution of the phylogeny from the Bayesian Markov chain Monte Carlo analysis to accommodate uncertainty in phylogenetic relationships. • Key results: The phylogeny shows that subtribe Cardopatiinae is sister to the remaining subtribes, and subtribes Carlininae and Echinopsinae appear as consecutive sister-clades to the Carduinae/Centaureinae. Tribe Cardueae is inferred to have originated around the Mid Eocene in West Asia, which is also the ancestral area of most subtribes within Cardueae. Diversification within each subtribe began during the Oligocene-Miocene period. • Conclusions: Most diversification events within Cardueae are related to the continuous cycles of area connection and division between the Anatolian microplate and the western Mediterranean Basin during the Oligocene-Miocene and with the uplift of the Himalayan range from the Miocene onward. From these two regions, thistles dispersed and colonized the rest of the continents (e.g., the New World, Africa, and Australia), most likely during the colder Pliocene-Pleistocene period.
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| 8. |
- Bartish, Igor V., et al.
(author)
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Fewer chromosomes, more co-occurring species within plant lineages : A likely effect of local survival and colonization
- 2023
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 110:4
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Journal article (peer-reviewed)abstract
- Premise:Plant lineages differ markedly in species richness globally, regionally, and locally. Differences in whole-genome characteristics (WGCs) such as monoploid chromosome number, genome size, and ploidy level may explain differences in global species richness through speciation or global extinction. However, it is unknown whether WGCs drive species richness within lineages also in a recent, postglacial regional flora or in local plant communities through local extinction or colonization and regional species turnover.Methods:We tested for relationships between WGCs and richness of angiosperm families across the Netherlands/Germany/Czechia as a region, and within 193,449 local vegetation plots.Results:Families that are species-rich across the region have lower ploidy levels and small monoploid chromosomes numbers or both (interaction terms), but the relationships disappear after accounting for continental and local richness of families. Families that are species-rich within occupied localities have small numbers of polyploidy and monoploid chromosome numbers or both, independent of their own regional richness and the local richness of all other locally co-occurring species in the plots. Relationships between WGCs and family species-richness persisted after accounting for niche characteristics and life histories.Conclusions:Families that have few chromosomes, either monoploid or holoploid, succeed in maintaining many species in local communities and across a continent and, as indirect consequence of both, across a region. We suggest evolutionary mechanisms to explain how small chromosome numbers and ploidy levels might decrease rates of local extinction and increase rates of colonization. The genome of a macroevolutionary lineage may ultimately control whether its species can ecologically coexist.
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| 9. |
- Bell, David, et al.
(author)
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Organellomic data sets confirm a cryptic consensus on (unrooted) land-plant relationships and provide new insights into bryophyte molecular evolution
- 2020
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 107:1, s. 91-115
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Journal article (peer-reviewed)abstract
- Premise Phylogenetic trees of bryophytes provide important evolutionary context for land plants. However, published inferences of overall embryophyte relationships vary considerably. We performed phylogenomic analyses of bryophytes and relatives using both mitochondrial and plastid gene sets, and investigated bryophyte plastome evolution. Methods We employed diverse likelihood-based analyses to infer large-scale bryophyte phylogeny for mitochondrial and plastid data sets. We tested for changes in purifying selection in plastid genes of a mycoheterotrophic liverwort (Aneura mirabilis) and a putatively mycoheterotrophic moss (Buxbaumia), and compared 15 bryophyte plastomes for major structural rearrangements. Results Overall land-plant relationships conflict across analyses, generally weakly. However, an underlying (unrooted) four-taxon tree is consistent across most analyses and published studies. Despite gene coverage patchiness, relationships within mosses, liverworts, and hornworts are largely congruent with previous studies, with plastid results generally better supported. Exclusion of RNA edit sites restores cases of unexpected non-monophyly to monophyly for Takakia and two hornwort genera. Relaxed purifying selection affects multiple plastid genes in mycoheterotrophic Aneura but not Buxbaumia. Plastid genome structure is nearly invariant across bryophytes, but the tufA locus, presumed lost in embryophytes, is unexpectedly retained in several mosses. Conclusions A common unrooted tree underlies embryophyte phylogeny, [(liverworts, mosses), (hornworts, vascular plants)]; rooting inconsistency across studies likely reflects substantial distance to algal outgroups. Analyses combining genomic and transcriptomic data may be misled locally for heavily RNA-edited taxa. The Buxbaumia plastome lacks hallmarks of relaxed selection found in mycoheterotrophic Aneura. Autotrophic bryophyte plastomes, including Buxbaumia, hardly vary in overall structure.
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| 10. |
- Bienau, Miriam J, et al.
(author)
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Clonality increases with snow depth in the arctic dwarf shrub Empetrum hermaphroditum.
- 2016
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In: American Journal of Botany. - : Botanical Society Of America. - 0002-9122 .- 1537-2197. ; 103:12, s. 2105-2114
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Journal article (peer-reviewed)abstract
- PREMISE OF THE STUDY: Vegetative reproduction and spread through clonal growth plays an important role in arctic-alpine ecosystems with short cool growing seasons. Local variation in winter snow accumulation leads to discrete habitat types that may provide divergent conditions for sexual and vegetative reproduction. Therefore, we studied variation in clonal structure of a dominant, evergreen, dwarf shrub (Empetrum nigrum s.l. with the two taxa E. nigrum L. s.s. and E. hermaphroditum Hagerup) along a snow cover gradient and compared clonal diversity and spatial genetic structure between habitats.METHODS: We studied 374 individual shoots using 105 polymorphic AFLP markers and analyses based on hierarchical clustering, clonal diversity indices, and small-scale spatial genetic structure with pairwise kinship coefficient. We used two approaches to define a threshold of genotypic distance between two samples that are considered the same clone. Clonality was examined among three habitats (exposed ridges, sheltered depressions, birch forest) differing in snow conditions replicated in four study regions in Norway and Sweden.KEY RESULTS: Clonality of E. hermaphroditum differed between habitats with an increase in clonal diversity with decreasing snow depth. Small-scale spatial genetic structure increased with decreasing clonal diversity and increasing clone size. In three study regions, E. hermaphroditum was the only species, whereas in one region E. nigrum also occurred, largely confined to exposed ridges.CONCLUSIONS: Our results demonstrated that snow cover in conjunction with associated habitat conditions plays an important role for the mode of propagation of the dwarf shrub E. hermaphroditum.
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| 11. |
- Blanco-Pastor, José Luis, et al.
(author)
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Evolutionary networks from RADseq loci point to hybrid origins of Medicago carstiensis and Medicago cretacea
- 2019
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 106:9, s. 1219-1228
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Journal article (peer-reviewed)abstract
- Premise Although hybridization has played an important role in the evolution of many plant species, phylogenetic reconstructions that include hybridizing lineages have been historically constrained by the available models and data. Restriction-site-associated DNA sequencing (RADseq) has been a popular sequencing technique for the reconstruction of hybridization in the next-generation sequencing era. However, the utility of RADseq for the reconstruction of complex evolutionary networks has not been thoroughly investigated. Conflicting phylogenetic relationships in the genus Medicago have been mainly attributed to hybridization, but the specific hybrid origins of taxa have not been yet clarified. Methods We obtained new molecular data from diploid species of Medicago section Medicago using single-digest RADseq to reconstruct evolutionary networks from gene trees, an approach that is computationally tractable with data sets that include several species and complex hybridization patterns. Results Our analyses revealed that assembly filters to exclusively select a small set of loci with high phylogenetic information led to the most-divergent network topologies. Conversely, alternative clustering thresholds or filters on the number of samples per locus had a lower impact on networks. A strong hybridization signal was detected for M. carstiensis and M. cretacea, while signals were less clear for M. rugosa, M. rhodopea, M. suffruticosa, M. marina, M. scutellata, and M. sativa. Conclusions Complex network reconstructions from RADseq gene trees were not robust under variations of the assembly parameters and filters. But when the most-divergent networks were discarded, all remaining analyses consistently supported a hybrid origin for M. carstiensis and M. cretacea.
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| 12. |
- Bolinder, Kristina, et al.
(author)
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AERODYNAMICS AND POLLEN ULTRASTRUCTURE IN EPHEDRA
- 2015
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 102:3, s. 457-470
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Journal article (peer-reviewed)abstract
- Premise of the study: Pollen dispersal is affected by the terminal settling velocity (U-t) of the grains, which is determined by their size, bulk density, and by atmospheric conditions. The likelihood that wind-dispersed pollen is captured by ovulate organs is influenced by the aerodynamic environment created around and by ovulate organs. We investigated pollen ultrastructure and U-t of Ephedra foeminea (purported to be entomophilous), and simulated the capture efficiency of its ovules. Results were compared with those from previously studied anemophilous Ephedra species. Methods: U-t was determined using stroboscopic photography of pollen in free fall. The acceleration field around an average ovule was calculated, and inflight behavior of pollen grains was predicted using computer simulations. Pollen morphology and ultrastructure were investigated using SEM and STEM. Key results: Pollen wall ultrastructure was correlated with U-t in Ephedra. The relative proportion and amount of granules in the infratectum determine pollen bulk densities, and (together with overall size) determine U-t and thus dispersal capability. Computer simulations failed to reveal any functional traits favoring anemophilous pollen capture in E. foeminea. Conclusion: The fast U-t and dense ultrastructure of E. foeminea pollen are consistent with functional traits that distinguish entomophilous species from anemophilous species. In anemophilous Ephedra species, ovulate organs create an aerodynamic microenvironment that directs airborne pollen to the pollination drops. In E. foeminea, no such microenvironment is created. Ephedroid palynomorphs from the Cretaceous share the ultrastructural characteristics of E. foeminea, and at least some may, therefore, have been produced by insect-pollinated plants.
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| 13. |
- Bouchal, Johannes Martin, 1979-
(author)
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EVOLUTIONARY TRENDS AND ECOLOGICAL DIFFERENTIATION IN EARLY CENOZOIC FAGACEAE OF WESTERN NORTH AMERICA
- 2014
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 101:8, s. 1332-1349
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Journal article (peer-reviewed)abstract
- • Premise of the study: The early Cenozoic was a key period of evolutionary radiation in Fagaceae. The common notion is thatspecies thriving in the modern summer-dry climate of California originated in climates with ample summer rain during thePaleogene.• Methods: We investigated in situ and dispersed pollen of Fagaceae from the uppermost Eocene Florissant fossil beds, Colorado,United States, using a combined light and scanning electron microscopy approach.• Key results: Pollen types of Castaneoideae with affi nities to modern Castanea , Lithocarpus , and Castanopsis were recognized.Pollen of the extinct genus Fagopsis represents a derived type of Castaneoideae pollen. Infrageneric groups of Quercus werewell represented, including pollen of Group Protobalanus. The taxonomic diversity of Fagaceae and of the total plant assemblageindicates a mosaic of microclimates, that range from pronounced to weakly seasonal climates and depend on slope aspectand elevation. Continental climatic conditions may have triggered the evolution of sclerophyllous leaves and adaptive radiationin Quercus and other taxa thriving today under distinctly summer-dry and winter-dry climates.• Conclusions: Vegetation types similar to modern vegetation belts of the Coastal Ranges (chaparral, nemoral conifer forest)were established in the Front Range in the late Eocene. Coeval plant assemblages from the Coastal Ranges of California indicatedistinctly subtropical, moist climates. Hence, characteristic elements found today in the summer-dry and winter-dry climatesof Pacifi c North America ( Quercus Group Protobalanus, Notholithocarpus ) may opportunistically have dispersed intotheir modern ranges later in the Cenozoic. This scenario is in contrast to the evolution and migration patterns of their westernEurasian Mediterranean counterparts ( Quercus Group Ilex).
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| 14. |
- Calvente, Alice, et al.
(author)
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Spiny but photogenic : amateur sightings complement herbarium specimens to reveal the bioregions of cacti
- 2023
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In: American Journal of Botany. - : John Wiley & Sons. - 0002-9122 .- 1537-2197. ; 110:10
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Journal article (peer-reviewed)abstract
- Premise: Cacti are characteristic elements of the Neotropical flora and of major interest for biogeographic, evolutionary, and ecological studies. We tested global biogeographic boundaries for Neotropical Cactaceae using specimen-based occurrences, coupled with data from visual observations, as a means to tackle the known collection biases in the family.Methods: Species richness and record density were assessed for preserved specimens and human observations, and a bioregional scheme tailored to Cactaceae was produced using the interactive web application Infomap Bioregions, based on data from 261,272 point records cleaned through automated and manual steps.Results: We found that areas in Mexico and southwestern USA, in eastern Brazil, and along the Andean region have the greatest density of records and the highest species richness. Human observations complement information from preserved specimens substantially, especially along the Andes. We propose 24 cactus bioregions, among which the most species-rich are northern Mexico/southwestern USA, central Mexico, southern central Mexico, Central America, Mexican Pacific coast, central and southern Andes, northwestern Mexico/extreme southwestern USA, southwestern Bolivia, northeastern Brazil, and Mexico/Baja California.Conclusions: The bioregionalization proposed shows biogeographic boundaries specific to cacti and can thereby aid further evolutionary, biogeographic, and ecological studies by providing a validated framework for further analyses. This classification builds upon, and is distinctive from, other expert-derived regionalization schemes for other taxa. Our results showcase how observation data, including citizen-science records, can complement traditional specimen-based data for biogeographic research, particularly for taxa with specific specimen collection and preservation challenges and those that are threatened or internationally protected.
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| 15. |
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| 16. |
- CARPENTER, RAYMOND, et al.
(author)
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EARLY EVIDENCE OF XEROMORPHY IN ANGIOSPERMS: STOMATAL ENCRYPTION IN A NEW EOCENE SPECIES OF BANKSIA (PROTEACEAE) FROM WESTERN AUSTRALIA
- 2014
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 101:9, s. 1486-1497
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Journal article (peer-reviewed)abstract
- Premise of the study: Globally, the origins of xeromorphic traits in modern angiosperm lineages are obscure but are thought to be linked to the early Neogene onset of seasonally arid climates. Stomatal encryption is a xeromorphic trait that is prominent in Banksia , an archetypal genus centered in one of the world’s most diverse ecosystems, the ancient infertile landscape of Mediterranean-climate southwestern Australia.Methods: We describe Banksia paleocrypta , a sclerophyllous species with encrypted stomata from silcretes of the Walebing and Kojonup regions of southwestern Australia dated as Late Eocene.Key results: Banksia paleocrypta shows evidence of foliar xeromorphy ~20 Ma before the widely accepted timing for the onset of aridity in Australia. Species of Banksia subgenus Banksia with very similar leaves are extant in southwestern Australia. The conditions required for silcrete formation infer fl uctuating water tables and climatic seasonality in southwestern Australia in the Eocene, and seasonality is supported by the paucity of angiosperm closed-forest elements among the fossil taxa preserved with B. paleocrypta. However, climates in the region during the Eocene are unlikely to have experienced seasons as hot and dry as present-day summers.Conclusions: The presence of B. paleocrypta within the center of diversity of subgenus Banksia in edaphically ancient southwestern Australia is consistent with the continuous presence of this lineage in the region for ≥ 40 Ma, a testament to the success of increasingly xeromorphic traits in Banksia over an interval in which numerous other lineages became extinct.
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| 17. |
- Dauphinee, Adrian
(author)
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The role of auxin in developmentally regulated programmed cell death in lace plant
- 2020
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 107, s. 577-586
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Journal article (peer-reviewed)abstract
- Premise Lace plant (Aponogeton madagascariensis) leaves are remodeled via developmental programmed cell death (PCD) to produce perforations located equidistantly between longitudinal and transverse veins. Auxin has been implicated in other developmental PCD processes in plants; however, the role of auxin in perforation formation in lace plant is unknown. Here the role of auxin in developmental PCD in lace plant was studied using two auxin inhibitors N-1-naphthylphthalamic acid (NPA), an auxin transport inhibitor, and auxinole, a potent auxin antagonist.Methods Sterile cultures of lace plants were propagated and treated with NPA or auxinole. Leaf length, leaf width, and number of perforations were then analyzed. Vein patterning and perforation area were further examined in NPA-treated plants. Downstream PCD transduction events were investigated via spectrophotometric assays, histochemical staining, and immuno-probing.Results Lace plants treated with NPA or auxinole produced leaves with fewer perforations compared to their respective controls. Although NPA treatment was insufficient to completely alter vein patterning, NPA-treated leaves did have significantly more atypical areoles compared to control leaves. Events involved in perforation formation in lace plant leaves were altered following treatment with NPA, including anthocyanin production, reactive oxygen species (ROS) accumulation, and the release of mitochondrial cytochrome c.Conclusions Our results indicated that inhibition of auxin signaling disrupts several downstream features of the lace plant PCD signaling cascade and results in fewer or no perforations. Therefore, we concluded that auxin signaling is important for developmentally regulated PCD in lace plant leaves.
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| 18. |
- Delgado-Salinas, Alfonso, et al.
(author)
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Vigna (Leguminosae) sensu lato : The names and identities of the American segregate
- 2011
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 98:10, s. 1694-1715
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Journal article (peer-reviewed)abstract
- • Premise of study: The legume genus Vigna and close relatives have highly elaborated floral morphologies that involve the coiling, bending, and intricate connection of flower parts. Banners, levers, platforms, and pumps have evolved that attract pollinators and then manipulate their movement. Given this three-dimensional floral complexity, the taxonomy of Vigna and relatives has been confounded by the study of mostly two-dimensional museum specimens. A molecular phylogenetic analysis was undertaken in the effort to resolve long-standing taxonomic questions centered on floral morphology. • Methods: The phylogenetic analysis included cpDNA trnK and nuclear ribosomal ITS/5.8S (ITS) sequence variation. The American species were comprehensively sampled and outgroups included Old World relatives. • Key results: The trnK and ITS data analyses concurred in resolving six well-supported clades of American Vigna that are most closely related to other American genera: Dolichopsis, Macroptilium, Mysanthus, Oryxis, Oxyrhynchus, Phaseolus, Ramirezella, and Strophostyles. These 14 American clades ranked here as genera are resolved as sister to a clade comprising the mainly Old World species of Vigna. • Conclusions: American Vigna clades were reassigned to the genera Ancistrotropis, Cochliasanthus, Condylostylis, Leptospron, Sigmoidotropis, and the newly described Helicotropis. Vigna sensu stricto in the Americas now includes relatively few and mostly pantropical species. Elaborate floral asymmetries are readily used to apomorphically diagnose nearly all of the American genera. The age estimates of the extant diversification of the American and its Old World sister clade are approximately coeval at ca. 6–7 million yr, which belies much greater floral variation in the Americas.
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| 19. |
- Denk, Thomas, et al.
(author)
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New Fagaceous pollen taxa from the Miocene Søby flora of Denmark and their biogeographic implications
- 2021
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In: American Journal of Botany. - : John Wiley & Sons. - 0002-9122 .- 1537-2197. ; 108, s. 1500-1524
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Journal article (peer-reviewed)abstract
- Premise: The Fagaceae comprise around 1000 tree species in the Northern Hemisphere.Despite an extensive fossil pollen record, reconstructing biogeographic patternsis hampered because it is difficult to achieve good taxonomic resolution withlight microscopy alone. We investigate dispersed pollen of Fagaceae from the Miocene Søby flora, Denmark. We explore the latitudinal gradient in Fagaceae distribution during the Miocene Climatic Optimum (MCO) in Europe and the Northern Hemisphere to compare it with the Eocene Warmhouse and the present.Methods: We investigated dispersed pollen using light and scanning electron microscopy. We assessed biogeographic patterns in Fagaceae during two warm periods in Earth history (MCO, Eocene) and the present.Results: Eight species of Fagaceae were recognized in the Søby flora. Of these, Fagus had a continuous Mediterranean to subarctic distribution during MCO; Quercus sect. Cerris and castaneoids had northern limits in Denmark, and evergreen Quercus sect. Ilex in Central Europe. In a northern hemispheric context, Fagus and sections of Quercus had more northerly distribution limits during Eocene and MCO with maximum northward extensions during Eocene (Fagus, castaneoids) or Oligo‐Miocene (Quercus sects. Cerris and Ilex). The known distribution of the extinct Tricolporopollenites theacoides during MCO included Central Europe and East China, while this taxon thrived in South China during Eocene.Conclusions: More northerly distributions during MCO and Eocene probably were determined by temperature. In contrast, fossil occurrences in areas that are arid or semi‐humid today were determined by maritime conditions in these areas (western North America, Central Asia) during the Cenozoic.
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| 20. |
- Dinnétz, Patrik
(author)
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Male sterility, Protogyny and Pollen-Pistil interference in Plantago maritima (Plantaginaceae) a wind-pollinated, self-incompatible perennial
- 1997
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In: American Journal of Botany. - 0002-9122 .- 1537-2197. ; 84:11, s. 1588-1594
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Journal article (peer-reviewed)abstract
- Evolution and maintenance of male sterility in seed plants can be explained by the maternal inheritance of mitochondria, which encode the trait, and by adaptive functions that enhance female fecundity in male-sterile compared to hermaphrodite individuals. Protogyny and male sterility can independently decrease the negative effect of pollen–pistil interference in selfincompatible species. In Plantago maritima, which possesses both traits, protogyny increases seed set in hermaphrodite individuals. This is shown both by a significantly positive association between seed set and retarded dehiscence of the anthers and by a more than 50% reduction in seed set following self-pollination. Male sterility does not seem to increase seed set further, as female and hermaphrodite plants do not differ significantly in mean seed set per capsule. Bagging experiments demonstrate strong self-incompatibility in the study populations. Hence, in P. maritima male sterility seems neither to prevent selfing nor to reduce the effect of pollen–pistil interference. Females had significantly larger stigmas than hermaphrodites, but seed set varied negatively with stigma length among females, indicating that the evolution of unisexuality in P. maritima is not due to prefertilization sex allocation. I therefore conclude that the genetical system of nucleocytoplasmic determination of gender is the main cause for maintenance of male sterility in P. maritima.
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| 21. |
- Eggens, F., et al.
(author)
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The origin and number of introductions of the Hawaiian endemic Silene species (Caryophyllaceae)
- 2007
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 94:2, s. 210-218
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Journal article (peer-reviewed)abstract
- The Hawaiian endemic Silene are a small group of woody or semiwoody representatives from a large, predominantly herbaceous, species-rich genus. We here investigated the origin and number of introductions of the endemic Hawaiian Silene based on phylogenetic relationships inferred from DNA sequences from both the plastid (the rps16 intron) and the nuclear (ribosomal internal transcribed sequences, ITS, and intron 23 of the RPB2 gene) genomes. Silene antirrhina, a widespread weedy American annual, is strongly supported as sister to a monophyletic group consisting of the Hawaiian Silene, indicating a single colonization event. There are no obvious morphological similarities between S. antirrhina and any of the species of Hawaiian Silene. Our results suggest an American origin for the Hawaiian endemics because that would require only a single trans-ocean dispersal. Two of the Hawaiian endemics (S. struthioloides and S. hawaiiensis) that form a subclade in the analyses have evolved woodiness after introduction to the Hawaiian Islands. Our results contribute to other recent results based on molecular phylogenetics that emphasize the American continent as a source area for the Hawaiian flora and support a striking morphological radiation and evolution of woodiness from a single introduction to the archipelago.
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| 22. |
- Eisen, Katherine E., et al.
(author)
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Among- and within-population variation in morphology, rewards, and scent in a hawkmoth-pollinated plant
- 2022
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 109:11, s. 1794-1810
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Journal article (peer-reviewed)abstract
- Premise: Floral scent is a complex trait that mediates many plant–insect interactions, but our understanding of how floral scent variation evolves, either independently or in concert with other traits, remains limited. Assessing variation in floral scent at multiple levels of biological organization and comparing patterns of variation in scent to variation in other floral traits can contribute to our understanding of how scent variation evolves in nature. Methods: We used a greenhouse common garden experiment to investigate variation in floral scent at three scales—within plants, among plants, and among populations—and to determine whether scent, alone or in combination with morphology and rewards, contributes to population differentiation in Oenothera cespitosa subsp. marginata. Its range spans most of the biomes in the western United States, such that variation in both the abiotic and biotic environment could contribute to trait variation. Results: Multiple analytical approaches demonstrated substantial variation among and within populations in compound-specific and total floral scent measures. Overall, populations were differentiated in morphology and reward traits and in scent. Across populations, coupled patterns of variation in linalool, leucine-derived compounds, and hypanthium length are consistent with a long-tongued moth pollination syndrome. Conclusions: The considerable variation in floral scent detected within populations suggests that, similar to other floral traits, variation in floral scent may have a heritable genetic component. Differences in patterns of population differentiation in floral scent and in morphology and rewards indicate that these traits may be shaped by different selective pressures.
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| 23. |
- Eiserhardt, W. L., et al.
(author)
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A roadmap for global synthesis of the plant tree of life
- 2018
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 105:3, s. 614-622
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Journal article (peer-reviewed)abstract
- Providing science and society with an integrated, up-to-date, high quality, open, reproducible and sustainable plant tree of life would be a huge service that is now coming within reach. However, synthesizing the growing body of DNA sequence data in the public domain and disseminating the trees to a diverse audience are often not straightforward due to numerous informatics barriers. While big synthetic plant phylogenies are being built, they remain static and become quickly outdated as new data are published and tree-building methods improve. Moreover, the body of existing phylogenetic evidence is hard to navigate and access for non-experts. We propose that our community of botanists, tree builders, and informaticians should converge on a modular framework for data integration and phylogenetic analysis, allowing easy collaboration, updating, data sourcing and flexible analyses. With support from major institutions, this pipeline should be re-run at regular intervals, storing trees and their metadata long-term. Providing the trees to a diverse global audience through user-friendly front ends and application development interfaces should also be a priority. Interactive interfaces could be used to solicit user feedback and thus improve data quality and to coordinate the generation of new data. We conclude by outlining a number of steps that we suggest the scientific community should take to achieve global phylogenetic synthesis.
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| 24. |
- Falahati-Anbaran, Mohsen, et al.
(author)
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Genetic consequences of seed banks in the perennial herb Arabidopsis lyrata subsp. petraea (Brassicaceae)
- 2011
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In: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 98:9, s. 1475-1485
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Journal article (peer-reviewed)abstract
- Premise of the Study: Seed banks may increase the effective population size (N(e)) of plants as a result of elevated coalescence times for alleles residing in the populations. This has been empirically demonstrated in populations of the annual Arabidopsis thaliana, whereas comparable data for perennial species are currently lacking. We studied the contribution of seed banks to effective sizes of natural populations of the self-incompatible, perennial Arabidopsis lyrata subsp. petraea, a close relative of A. thaliana. Methods: Fourteen populations of A. lyrata collected throughout the Norwegian distribution range were analyzed using micro-satellite markers. Key Results: The genetic composition of seed-bank and aboveground cohorts was found to be highly similar, with little genetic differentiation between cohorts in most populations. However, the proportion of private alleles was higher in aboveground than in seed-bank cohorts. The presence of seed banks significantly increased total N(e), but the contribution from seed banks to overall N(e) were lower than the contribution from aboveground cohorts in most populations. Estimated historical N(e) values, reflecting the effective sizes of populations throughout the history of the species, were considerably higher than estimates of contemporary N(e), reflecting number of reproducing individuals within the past few generations. Conclusions: The results show that the seed bank contributes to total N(e) in the perennial herb A. lyrata. However, the contribution is similar to or lower than that of the above-ground fraction of the population and markedly weaker than that previously documented in the annual A. thaliana.
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| 25. |
- Fogelström, Elsa, et al.
(author)
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Spring and autumn phenology in an understory herb are uncorrelated and driven by different factors
- 2022
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In: American Journal of Botany. - : John Wiley & Sons. - 0002-9122 .- 1537-2197. ; 109:2, s. 226-236
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Journal article (peer-reviewed)abstract
- Premise Climate warming has altered the start and end of growing seasons in temperate regions. Ultimately, these changes occur at the individual level, but little is known about how previous seasonal life-history events, temperature, and plant-resource state simultaneously influence the spring and autumn phenology of plant individuals.Methods We studied the relationships between the timing of leaf-out and shoot senescence over 3 years in a natural population of the long-lived understory herb Lathyrus vernus and investigated the effects of spring temperature, plant size, reproductive status, and grazing on spring and autumn phenology.Results The timing of leaf-out and senescence were consistent within individuals among years. Leaf-out and senescence were not correlated with each other within years. Larger plants leafed out and senesced later, and size had no effect on growing season length. Reproductive plants leafed out earlier and had longer growing seasons than nonreproductive plants. Grazing had no detectable effects on phenology. Colder spring temperatures delayed senescence in two of three study years.Conclusions The timing of seasonal events, such as leaf-out and senescence in plants can be expressed largely independently within and among seasons and are influenced by different factors. Growing season start and length can often be dependent on plant condition and reproductive status. Knowledge about the drivers of growing season length of individuals is essential to more accurately predict species and community responses to environmental variation.
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