Hirmeriella muensteri: New data on the fertile organs leading to a revised concept of the Cheiroleopiaeae

Clement-Westerhof, Jopie A.; Cittert, Johanna H.A. van Konijnenburg‐van

doi:10.1016/0034-6667(91)90062-8

Cited by 57 publications

(53 citation statements)

References 11 publications

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“…It has been suggested that the complex wall structure may have served as a biochemical recognition mechanism for taxonomical compatibility [40]. Moreover, seeds of the Cheirolepidiaceae are covered by a double integumentum that opened proximally on the scale [41]. This feature, uncommon in gymnosperms would imply that the pollen did not have direct access to the ovule micropyle and may have germinated on the scale.…”

Section: Discussionmentioning

confidence: 99%

Aberrant Classopollis pollen reveals evidence for unreduced (2 n ) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition

2013

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Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic-Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis.

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Section: Discussionmentioning

confidence: 99%

Aberrant Classopollis pollen reveals evidence for unreduced (2 n ) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition

2013

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“…For instance, Pararaucaria patagonica (Cheirolepidiaceae), from the Middle Jurassic of Argentina, has ovuliferous scale tissues that partially enclose a single seed (rarely two ;Calder 1953;Stockey 1977). Interestingly, covering tissues in Cheirolepidaceae have previously been interpreted as an epimatium (Clement-Westerhof and van Konijnenburg-van Cittert 1991;Del Fueyo et al 2008;contra Escapa et al 2012acontra Escapa et al , 2012b) based on the positional congruence between this ovule-enclosing tissue and the podocarpaceous epimatium. Nevertheless, phylogenetic relationships between the extinct Mesozoic family Cheirolepidaceae and other modern conifer families (e.g., Araucariaceae, Podocarpaceae, Pinaceae) are not fully understood, and any proposed homology hypotheses for these ovulate cone traits are still quite speculative.…”

Section: Relationships Of Extant Araucariaceaementioning

confidence: 99%

Phylogenetic Analysis of Araucariaceae: Integrating Molecules, Morphology, and Fossils

Escapa

Catalano

2013

International Journal of Plant Sciences

119

103

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Premise of research. Phylogenetic relationships of Araucariaceae (Coniferophyta, Araucariales) are revised on the basis of the first combined data matrix for the family.Methodology. Taxon sampling includes 39 ingroup species (31 extant, 8 fossils) and outgroup species of all the remaining conifer families. Five fossil Araucaria species, one species of the genus Araucarites, and two species of the extinct genera Wairarapaia and Emwadea were included in the analyses. Character sampling includes 23 genomic regions (19 plastid, 2 nuclear, and 2 mitochondrial) and 62 morphological characters (52 discrete and 10 continuous). The phylogenetic analyses were conducted with equally weighted parsimony. Additionally, several analyses under different taxon-and gene-sampling regimes were analyzed for identifying the causes of the long-lasting controversies in the interrelationships of the three extant genera of Araucariaceeae.Pivotal results. Monophyletic Araucariaceae is the sister group of Podocarpaceae, forming the order Araucariales. Monophyly of Araucaria and Agathis is also strongly supported by the data. The results of both molecular and combined analyses indicate that Wollemia and Agathis form a clade (pagathioid clade) sister to Araucaria. Within Araucaria, the analyses support the monophyly of the four currently recognized sections: Araucaria, Bunya, Intermedia, and Eutacta. Results support the monophyly of living and fossil Araucaria (including Araucarites), whereas the remaining extinct genera are placed as the stem of the agathioid clade. In terms of the sensitivity analyses performed, results suggest that inconsistencies among previous results would be related to ingroup sampling.Conclusions. By means of a combined phylogenetic analysis, we have been able to obtain a strongly supported and well-resolved phylogeny of Araucariaceae that includes both living species and fossil species for the group. This study shows the feasibility and usefulness of phylogenetic analyses that incorporate multiple sources of evidence (molecules/morphology, living/fossil species, discrete/continuous characters).

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“…Second are features of individual Classopollis grains, including their comparatively large size (Figs. 3J, N, P, R, T), thick exine, and grains occurring as tetrads held together by sticky exinal threads (Taylor & Alvin, 1984;Clement-Westerhof & van Konijnenburg-van Gittert, 1991). Third is the presence of pollen tetrads and single pollen grains of Classopollis on the heads of likely Late Jurassic and Early Cretaceous pollinating insects.…”

Section: • Two Probable Mesozoic Pollination Syndromes On Gymnospermsmentioning

confidence: 99%

Generalist flowers and phytophagous beetles in two tropical canopy trees: resources for multitudes

Ødegaard

Frame²

2007

TAXON

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Recent focus on plant-insect associations during the angiosperm radiation from the last 30 million years of the Early Cretaceous has inadvertently de-emphasized a similar but earlier diversification that occurred among gymnosperms. The existence of gymnosperm-insect associations during the preangiospermous Mesozoic is evidenced by mouthparts capable of reaching and imbibing pollination drops or similar fluids, availability of pollen types consistent with entomophily, and opportunities for related consumption of pollen, seeds, and reproductively associated tissues in major seed-plant groups, namely seed ferns, conifers, cycads, bennettitaleans, and gnetaleans. Based on stereotypical plant damage, head-adherent pollen, gut contents, wing structure, mouthpart morphology and insect damage to plant reproductive organs, the likely nectarivores, pollinivores and pollinators were orthopterans, phasmatodeans, webspinners, sawf lies and wasps, moths, beetles, mecopteroids, and true flies. These associations are ranked from possible to probable although the last three insect clades provide the strongest evidence for pollinator activity. We document two mid Cretaceous examples of these associations•cycadeoideaceous bennettitaleans and beetles and a cheirolepidiaceous conifer and flies•for which there are multiple lines of evidence for insect consumption of plant reproductive tissues but also pollination mutualisms. These data highlight the independent origin of a major phase of plant-insect pollinator-related associations during the mid Mesozoic that served as a prelude for the separate, iterative and later colonization of angiosperms.

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Hirmeriella muensteri: New data on the fertile organs leading to a revised concept of the Cheiroleopiaeae

Cited by 57 publications

References 11 publications

Aberrant Classopollis pollen reveals evidence for unreduced (2 n ) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition

Aberrant Classopollis pollen reveals evidence for unreduced (2 n ) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition

Phylogenetic Analysis of Araucariaceae: Integrating Molecules, Morphology, and Fossils

Generalist flowers and phytophagous beetles in two tropical canopy trees: resources for multitudes

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