| 1. |
- Anderberg, Arne A., et al.
(författare)
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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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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 89:4, s. 677-687
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Barbolini, Natasha, et al.
(författare)
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Cenozoic evolution of the steppe-desert biome in Central Asia
- 2020
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:41
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Forskningsöversikt (refereegranskat)abstract
- The origins and development of the arid and highly seasonal steppe-desert biome in Central Asia, the largest of its kind in the world, remain largely unconstrained by existing records. It is unclear how Cenozoic climatic, geological, and biological forces, acting at diverse spatial and temporal scales, shaped Central Asian ecosystems through time. Our synthesis shows that the Central Asian steppe-desert has existed since at least Eocene times but experienced no less than two regime shifts, one at the Eocene-Oligocene Transition and one in the mid-Miocene. These shifts separated three successive stable states, each characterized by unique floral and faunal structures. Past responses to disturbance in the Asian steppe-desert imply that modern ecosystems are unlikely to recover their present structures and diversity if forced into a new regime. This is of concern for Asian steppes today, which are being modified for human use and lost to desertification at unprecedented rates.
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| 3. |
- Bolinder, Kristina, et al.
(författare)
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AERODYNAMICS AND POLLEN ULTRASTRUCTURE IN EPHEDRA
- 2015
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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 102:3, s. 457-470
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Bolinder, Kristina, et al.
(författare)
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From near extinction to diversification by means of ashift in pollination mechanism in the gymnosperm relict Ephedra (Ephedraceae, Gnetales)
- 2016
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Ingår i: Botanical journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 180:4, s. 461-477
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Tidskriftsartikel (refereegranskat)abstract
- Pollination in gymnosperms is usually accomplished by means of wind, but some groups are insect-pollinated. We show that wind and insect pollination occur in the morphologically uniform genus Ephedra (Gnetales). Based on field experiments over several years, we demonstrate distinct differences between two Ephedra species that grow in sympatry in Greece in pollen dispersal and clump formation, insect visitations and embryo formation when insects are denied access to cones. Ephedra distachya, nested in the core clade of Ephedra, is anemophilous, which is probably the prevailing state in Ephedra. Ephedra foeminea, sister to the remaining species of the genus, is entomophilous and pollinated by a range of diurnal and nocturnal insects. The generalist entomophilous system of E.foeminea, with distinct but infrequent insect visitations, is in many respects similar to that reported for Gnetum and Welwitschia and appears ancestral in Gnetales. The Ephedra lineage is well documented already from the Early Cretaceous, but the diversity declined dramatically during the Late Cretaceous, possibly to near extinction around the Cretaceous-Palaeogene boundary. The clade imbalance between insect- and wind-pollinated lineages is larger than expected by chance and the shift in pollination mode may explain why Ephedra escaped extinction and began to diversify again.
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| 5. |
- Bolinder, Kristina, 1987-
(författare)
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Pollen and pollination in Ephedra (Gnetales)
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ephedra (Gnetales) is a gymnosperm genus with a long evolutionary history; the first dispersed pollen grains with affinity to the group are known already from the Permian. This thesis focuses on the evolutionary history of the group and different aspects of its pollination mechanisms. Despite the limited number of extant species of the genus (50-60), and a low morphological and genetic divergence among species, there is variation in pollination syndrome in the genus. The prevailing state in Ephedra, and most gymnosperms, is wind pollination. It is therefore surprising that one species, E. foeminea, is insect-pollinated. Together with co-workers I documented the pollination syndromes of E. foeminea and a sympatric species, E. distachya, based on long term field experiments in north-eastern Greece and aerodynamic investigations and calculations. Placing the results into an evolutionary framework reveals that the insect-pollinated species E. foeminea is sister to the remaining (mostly wind-pollinated) genus, and indicates that insect pollination is the ancestral state in the Gnetales. During the course of evolution of the group there has been a shift to wind pollination, which may have played a crucial role for the diversification of the crown group in the Paleogene. Pollination biology is often correlated with the morphology of the pollen such that pollen grains of anemophilous plants are small with a smooth surface, whereas pollen grains of entomophilous plants are larger with an ornamented surface and a covering of pollenkitt. The pollen morphology of Ephedra can be broadly divided into two types: an ancestral type with an unbranched pseudosulcus between each pair of plicae, and a derived type with a branched pseudosulcus between each pair of plicae. Further, the pollen morphology and ultrastructure of the pollen wall in Ephedra are to some degree correlated with the pollination syndrome and capability of long distance dispersal. Pollen of E. foeminea has a denser ultrastructure, as a result a higher settling velocity and is therefore capable of flying shorter distances than does pollen of the anemophilous E. distachya, and other investigated anemophilous species that show a more spacious ultrastructure of the pollen grain. These results can be useful in the reconstruction of the pollination mechanism of extinct taxa of the Ephedra-lineage in the future.
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| 6. |
- Bolinder, Kristina, et al.
(författare)
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Pollen morphology of Ephedra (Gnetales) and its evolutionary implications
- 2016
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Ingår i: Grana. - : Informa UK Limited. - 0017-3134 .- 1651-2049. ; 55:1, s. 24-51
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Tidskriftsartikel (refereegranskat)abstract
- The Ephedra lineage can be traced at least to the Early Cretaceous. Its characteristically polyplicate pollen is well-represented in the fossil record and is frequently used as an indicator of paleoclimate. However, despite previous efforts, knowledge about variation and evolution of ephedroid pollen traits is poor. Here, we document pollen morphology of nearly all extant species of Ephedra, using a combination of scanning electron microscopy (SEM) and light microscopy (LM), and reconstruct ancestral states of key pollen traits. Our results indicate that the ancestral Ephedra pollen type has numerous plicae interspaced by unbranched pseudosulci, while the derived pollen type has branched pseudosulci and (generally) fewer plicae. The derived type is inferred to have evolved independently twice, once along the North American stem branch and once along the Asian stem branch. Pollen of the ancestral type is common in Mesozoic fossil records, especially from the Early Cretaceous, but it is less commonly reported from the Cenozoic. The earliest documentation of the derived pollen type is from the latest Cretaceous, after which it increases strongly in abundance during the Paleogene. The results of the present study have implications for the age of crown group Ephedra as well as for understanding evolution of pollination syndromes in the genus.
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| 7. |
- Bolinder, Kristina
(författare)
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Pollination in Ephedra (Gnetales)
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pollination, i.e., the transport of male gametophytes to female gametophytes, can occur with biotic or abiotic vectors and is necessary for fertilization and completion of the lifecycle in all seed plants. Insect pollination and the co-evolution between angiosperms and insects have during the last century been discussed as one possible solution to Darwin’s abominable mystery and an important explanation for the relatively abrupt turn-over from a vegetation dominated by gymnosperms to a vegetation dominated by angiosperms in the Cretaceous. Insect pollination is, however, a much older phenomenon that can be traced back to the Devonian, but is it an ancestral trait that has been lost in many seed plant groups, or has it originated multiple times in parallel? These questions have to be addressed in a phylogenetic framework comprising extant and extinct seed plant groups. The Gnetales are constantly in focus in studies of seed plant phylogeny, probably because they have repeatedly been suggested, and refuted, to be the closest living relatives of angiosperms. The order consists of three genera, Gnetum, Welwitschia and Ephedra, of which the former two have long been known to be insect pollinated. Pollination biology in Ephedra has, however, been poorly studied and understood. In this thesis pollination mechanisms in Ephedra (Gnetales) are investigated by field experiments and observations (Paper I) and aerodynamic simulations and studies of pollen morphology (Paper II). The results show that there are multiple pollination mechanisms within this otherwise morphologically and ecologically uniform genus. Further, in contrast to what has often been assumed, insect pollination is shown to be ancestral in the Gnetales and not a derived feature that has evolved within the group. Using this new information on pollination biology in the Gnetales and data from the literature, I explore evolution of pollen morphology and pollination mode in seed plants.
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| 8. |
- Borges, Rodrigo Lopes, et al.
(författare)
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Phylogeny of the Neotropical element of the Randia clade (Gardenieae, Rubiaceae, Gentianales)
- 2021
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Ingår i: Plant Ecology and Evolution. - : Agentschap Plantentuin Meise. - 2032-3913 .- 2032-3921. ; 154:3, s. 458-469
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims – Generic limits of the tropical tribe Gardenieae (Ixoroideae, Rubiaceae) have partly remained unsettled. We produced a new phylogeny of the Randia clade, with emphasis on its Neotropical clade comprising five genera (Casasia, Randia, Rosenbergiodendron, Sphinctanthus, and Tocoyena). The result was subsequently used to evaluate and discuss: a) the respective monophyly of the above-mentioned genera and their interrelationships; b) relationships within Tocoyena and the evolutionary relevance of its subgeneric classification; and c) the monophyly of the morphologically variable T. formosa.Material and methods – We examined the phylogeny of the Randia clade based on maximum likelihood and Bayesian analyses of sequence data from two nuclear (ETS and Xdh) and two plastid (petB-petD and trnT-F) DNA regions from 59 individuals (including seven representatives from the remaining Ixoroideae).Key results – The Neotropical clade of the Randia clade comprises three major lineages, the Randia armata subclade, the Randia-Casasia subclade and the Rosenbergiodendron subclade. Neither Casasia nor Randia is monophyletic. Tocoyena is sister to Rosenbergiodendron + Sphinctanthus and is subdivided into three lineages: the Tocoyena pittieri group, the Tocoyena guianensis group, and the core Tocoyena. Tocoyena williamsii is paraphyletic with respect to T. pittieri. Tocoyena formosa is polyphyletic and should be re-circumscribed.Conclusions – Our results demonstrate the monophyly of each of the relatively species-poor genera Rosenbergiodendron, Sphinctanthus, and Tocoyena, and confirm their close affinity. The serial classification of Tocoyena does not reflect the evolutionary history of the genus. The paraphyly of T. williamsii with respect to T. pittieri, together with their morphological similarities and geographic distributions, support the inclusion of the former in the latter. Our study calls for additional phylogenetic work on Casasia and the more species-rich genus Randia. While the respective monophyly of both genera is rejected here, future work with a broader representation of Randia is needed.
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| 9. |
- Evkaikina, Anastasiia I., et al.
(författare)
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The Huperzia selago Shoot Tip Transcriptome Sheds New Light on the Evolution of Leaves
- 2017
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653 .- 1759-6653. ; 9:9, s. 2444-2460
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Tidskriftsartikel (refereegranskat)abstract
- Lycopodiophyta-consisting of three orders, Lycopodiales, Isoetales and Selaginellales, with different types of shoot apical meristems (SAMs)-form the earliest branch among the extant vascular plants. They represent a sister group to all other vascular plants, from which they differ in that their leaves are microphylls-that is, leaves with a single, unbranched vein, emerging from the protostele without a leaf gap-not megaphylls. All leaves represent determinate organs originating on the flanks of indeterminate SAMs. Thus, leaf formation requires the suppression of indeterminacy, that is, of KNOX transcription factors. In seed plants, this is mediated by different groups of transcription factors including ARP and YABBY. We generated a shoot tip transcriptome of Huperzia selago (Lycopodiales) to examine the genes involved in leaf formation. Our H. selago transcriptome does not contain any ARP homolog, although transcriptomes of Selaginella spp. do. Surprisingly, we discovered a YABBY homolog, although these transcription factors were assumed to have evolved only in seed plants. The existence of a YABBY homolog in H. selago suggests that YABBY evolved already in the common ancestor of the vascular plants, and subsequently was lost in some lineages like Selaginellales, whereas ARP may have been lost in Lycopodiales. The presence of YABBY in the common ancestor of vascular plants would also support the hypothesis that this common ancestor had a simplex SAM. Furthermore, a comparison of the expression patterns of ARP in shoot tips of Selaginella kraussiana (Harrison CJ, et al. 2005. Independent recruitment of a conserved developmental mechanism during leaf evolution. Nature 434(7032): 509-514.) and YABBY in shoot tips of H. selago implies that the development of microphylls, unlike megaphylls, does not seem to depend on the combined activities of ARP and YABBY. Altogether, our data show that Lycopodiophyta are a diverse group; so, in order to understand the role of Lycopodiophyta in evolution, representatives of Lycopodiales, Selaginellales, as well as of Isoetales, have to be examined.
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| 10. |
- Ferm, Julia, et al.
(författare)
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Phylogenetic relationships of the mimosoid Ingeae–Acacia complex (Fabaceae), based on plastid and nuclear data
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Modern phylogenetic analyses based on molecular data have shown that the current classification of the Ingeae tribe (Caesalpinioideae, Fabaceae) do not always reflect evolutionary relationships. Many genera that are currently defined based on morphological characters do not constitute monophyletic groups and generic relationships within the tribe are not fully known. Moreover, the Ingeae tribe itself does not comprise a monophyletic group since the genus Acacia (tribe Acacieae) is nested among the ingoid species. We investigated phylogenetic relationships of the Ingeae−Acacia complex on a generic level. We put special emphasis on genera with a taxonomic history in Calliandra s.l., i.e. Calliandra s.s., Afrocalliandra, Sanjappa, Viguieranthus and Zapoteca, and also the genus Faidherbia, which has been shown to be closely related to these genera in previous phylogenetic studies. We included samples from 32 ingoid genera, samples of Acacia and Senegalia (tribe Acacieae), and Vachellia farnesiana, which was used for rooting the trees. Datasets included the nuclear ETS and ITS, and the plastid matK, trnL-trnF and ycf1 DNA regions and were analysed with Bayesian inference and Ultrafast Bootstrap. The results show that the species of the Ingeae−Acacia complex are resolved in three major clades. Calliandra s.s. together with Afrocalliandra (Clade 1) is the sister to all remaining species of Ingeae and Acacia (Clades 2 and 3). Clade 2 comprises Faidherbia, Sanjappa, Thailentadopsis, Viguieranthus and Zapoteca. Clade 2 and Clade 3 are sisters, and thus the genera of Clade 2 are more closely related to each other and to the taxa of Clade 3, than to Calliandra s.s. and Afrocalliandra (Clade 1). The genera of Clades 1 and 2 all have the same type of pod, the typical “Calliandra-pod”, with Faidherbia being the only exception. Our results show that the “Calliandra-pod” is not a sign of evolutionary relationship within the Ingeae-Acacia complex. Rather this character evolved independently several times, also in clades outside of the Ingeae−Acacia complex. Another example is seen in the leaf structure within the Ingeae−Acacia complex. The possession of pinnate leaves defines the genus Inga (Clade 3) but is also present in the other two major clades (Clades 1 and 2) within the Ingeae−Acacia complex. It seems like the occurrence of pinnate leaves evolved at least three times within the Ingeae-Acacia complex. Another possibility is that the possession of pinnate leaves represents the ancestral state. However, within the mimosoids bipinnate leaves is the most common leaf morphology and the logical conclusion is that bipinnate leaves is the ancestral state. The most common polyad structure within the Ingeae−Acacia complex is 16-grained acalymmate polyads, but exceptions to this is present in Calliandra s.s., Afrocalliandra, Faidherbia and Acacia. Moreover, Calliandra s.s. is the only genus with calymmate polyads. Polyad structure could be useful for the generic classification of the Ingeae−Acacia complex but needs to be combined with other morphological characters. It seems likely that the ancestral state of polyad structure within the Ingeae-Acacia complex is acalymmate polyads and thus that the calymmate polyads seen in Calliandra are secondarily derived.
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