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Xiangrui Chen - One of the best experts on this subject based on the ideXlab platform.
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morphology and infraciliature of two new marine ciliates paracyrtophoron tropicum nov gen nov spec and aegyria Rostellum nov spec ciliophora cyrtophorida isolated from tropical waters in southern china
European Journal of Protistology, 2012Co-Authors: Xiangrui Chen, Jun Gong, Khaled A S Alrasheid, Saleh A Alfarraj, Weibo SongAbstract:The morphology and infraciliature of two new marine cyrtophorid ciliates, Paracyrtophoron tropicum nov. gen., nov. spec. and Aegyria Rostellum nov. spec., isolated from tropical waters in southern China, were investigated using live observation and protargol impregnation methods. Paracyrtophoron nov. gen. differs from the closely related Cyrtophoron by lack of fragment kinety at anterior ends of right somatic kinetics and thigmotactic cilia in posterior portion of ventral surface, while from the well-defined Chlamydodon by lack of the cross-striped band around the periphery of the somatic field. Paracyrtophoron tropicum nov. spec., the type of the new genus, can be recognized by the combination of the following characters: cell size about 150-175 x 70-90 mu m in vivo; elliptical to kidney-shaped in outline, dorsoventrally flattened about 2.5:1; conspicuous cortical granules; one canal-like depression extending from postoral area to subcaudal region of cell; ca. 90 somatic kinetics; 12-16 nematodesmal rods; one or two terminal fragments on dorsal side. Aegyria Rostellum is characterized by the following features: size about 90-150 x 40-70 mu m in vivo, triangular or ear-shaped body with broad anterior end, having a rostriform structure and pigment spots, 56-63 somatic kinetics, one preoral kinety, three or four circumoral kinetics, and 32-42 nematodesmal rods. Based on previous and current studies, the definition for the genus Aegyria is updated: body dorsoventrally flattened; oral ciliature consisting of one preoral and several circumoral kinetics; podite located in posterior ventral region and surrounded by somatic kinetics; no obvious gap between right and left somatic kinetics; postoral and left somatic kinetics progressively shortened posteriorly from right to left. Additionally, two new combinations were proposed.
Weibo Song - One of the best experts on this subject based on the ideXlab platform.
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morphology and infraciliature of two new marine ciliates paracyrtophoron tropicum nov gen nov spec and aegyria Rostellum nov spec ciliophora cyrtophorida isolated from tropical waters in southern china
European Journal of Protistology, 2012Co-Authors: Xiangrui Chen, Jun Gong, Khaled A S Alrasheid, Saleh A Alfarraj, Weibo SongAbstract:The morphology and infraciliature of two new marine cyrtophorid ciliates, Paracyrtophoron tropicum nov. gen., nov. spec. and Aegyria Rostellum nov. spec., isolated from tropical waters in southern China, were investigated using live observation and protargol impregnation methods. Paracyrtophoron nov. gen. differs from the closely related Cyrtophoron by lack of fragment kinety at anterior ends of right somatic kinetics and thigmotactic cilia in posterior portion of ventral surface, while from the well-defined Chlamydodon by lack of the cross-striped band around the periphery of the somatic field. Paracyrtophoron tropicum nov. spec., the type of the new genus, can be recognized by the combination of the following characters: cell size about 150-175 x 70-90 mu m in vivo; elliptical to kidney-shaped in outline, dorsoventrally flattened about 2.5:1; conspicuous cortical granules; one canal-like depression extending from postoral area to subcaudal region of cell; ca. 90 somatic kinetics; 12-16 nematodesmal rods; one or two terminal fragments on dorsal side. Aegyria Rostellum is characterized by the following features: size about 90-150 x 40-70 mu m in vivo, triangular or ear-shaped body with broad anterior end, having a rostriform structure and pigment spots, 56-63 somatic kinetics, one preoral kinety, three or four circumoral kinetics, and 32-42 nematodesmal rods. Based on previous and current studies, the definition for the genus Aegyria is updated: body dorsoventrally flattened; oral ciliature consisting of one preoral and several circumoral kinetics; podite located in posterior ventral region and surrounded by somatic kinetics; no obvious gap between right and left somatic kinetics; postoral and left somatic kinetics progressively shortened posteriorly from right to left. Additionally, two new combinations were proposed.
Hans Peter Comes - One of the best experts on this subject based on the ideXlab platform.
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Multiple independent origins of auto-pollination in tropical orchids (Bulbophyllum) in light of the hypothesis of selfing as an evolutionary dead end
BMC Evolutionary Biology, 2015Co-Authors: Alexander Gamisch, Gunter Alexander Fischer, Hans Peter ComesAbstract:Background The transition from outcrossing to selfing has long been portrayed as an ‘evolutionary dead end’ because, first, reversals are unlikely and, second, selfing lineages suffer from higher rates of extinction owing to a reduced potential for adaptation and the accumulation of deleterious mutations. We tested these two predictions in a clade of Madagascan Bulbophyllum orchids (30 spp.), including eight species where auto-pollinating morphs (i.e., selfers, without a ‘Rostellum’) co-exist with their pollinator-dependent conspecifics (i.e., outcrossers, possessing a Rostellum). Specifically, we addressed this issue on the basis of a time-calibrated phylogeny by means of ancestral character reconstructions and within the state-dependent evolution framework of BiSSE (Binary State Speciation and Extinction), which allowed jointly estimating rates of transition, speciation, and extinction between outcrossing and selfing. Results The eight species capable of selfing occurred in scattered positions across the phylogeny, with two likely originating in the Pliocene (ca. 4.4–3.1 Ma), one in the Early Pleistocene (ca. 2.4 Ma), and five since the mid-Pleistocene (ca. ≤ 1.3 Ma). We infer that this scattered phylogenetic distribution of selfing is best described by models including up to eight independent outcrossing-to-selfing transitions and very low rates of speciation (and either moderate or zero rates of extinction) associated with selfing. Conclusions The frequent and irreversible outcrossing-to-selfing transitions in Madagascan Bulbophyllum are clearly congruent with the first prediction of the dead end hypothesis. The inability of our study to conclusively reject or support the likewise predicted higher extinction rate in selfing lineages might be explained by a combination of methodological limitations (low statistical power of our BiSSE approach to reliably estimate extinction in small-sized trees) and evolutionary processes (insufficient time elapsed for selfers to go extinct). We suggest that, in these tropical orchids, a simple genetic basis of selfing (via loss of the ‘Rostellum’) is needed to explain the strikingly recurrent transitions to selfing, perhaps reflecting rapid response to parallel and novel selective environments over Late Quaternary (≤ 1.3 Ma) time scales.
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histological and micro ct evidence of stigmatic Rostellum receptivity promoting auto pollination in the madagascan orchid bulbophyllum bicoloratum
PLOS ONE, 2013Co-Authors: Alexander Gamisch, Yannick M. Staedler, Jürg Schönenberger, Gunter A. Fischer, Hans Peter ComesAbstract:Background The Rostellum, a projecting part of the gynostemium in orchid flowers, separates the anther(s) from the stigma and thus commonly prevents auto-pollination. Nonetheless, as a modified (usually distal) portion of the median stigma lobe, the Rostellum has been frequently invoked of having re-gained a stigmatic function in rare cases of orchid auto-pollination. Here it is shown that a newly discovered selfing variant of Madagascan Bulbophyllumbicoloratum has evolved a modified Rostellum allowing the penetration of pollen tubes from in situ pollinia.
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Apical gynostemium structures of Bulbophyllum bicoloratum viewed under the stereomicroscope (A, B) and scanning electron microscope (C–E).
2013Co-Authors: Alexander Gamisch, Yannick M. Staedler, Jürg Schönenberger, Gunter A. Fischer, Hans Peter ComesAbstract:(A) Isolated column of an outcrossing individual with erect Rostellum at anthesis (without pollinia); (B) isolated column of a selfing individual with ‘displaced’ (suberect) Rostellum at pre-anthesis (note, at anthesis, swollen pollina will obstruct the view on the Rostellum; compare E); (C) column of a selfing individual with pollinia still in the anther at pre-anthesis; (D) close-up of the ‘displaced’ (suberect) Rostellum (same as C) with the viscidium at its apex and cuticular folds on the upper (adaxial) side (except for the lateral sides); (E) column of a selfing individual after pollinia have been released from the anther onto the ‘displaced’ (suberect) Rostellum. The swollen outer pollinia contact the (semi-) lateral rims of the stigmatic cavity (arrow). The dashed lines of planes 1–3 indicate approximate positions of longitudinal micro-CT sections shown in Figure 4A–C, respectively. The arrow below indicates the directionality of the complete scan (see Video S3), with numbers identifying scan-frames roughly corresponding to planes 1–3. Abbreviations: a, anther; c, column (gynostemium); dr, ‘displaced’ (suberect) Rostellum (with cuticular folding); lr, lateral sides of ‘displaced’ (suberect) Rostellum (devoid of cuticular folding); p, pollinia; ip, inner pollinium; op, outer pollinium; r, Rostellum; s, stigmatic cavity; sr, rim of stigmatic cavity; st, stelidium; v, viscidium. Scale bars: (A, B) = 0.5 mm; (C, E) = 0.2 mm; (D) = 0.1 mm.
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Longitudinal semithin sections through the stigmatic cavity and Rostellum of an outcrosser (A) and selfer (B) of Bulbophyllum bicoloratum.
2013Co-Authors: Alexander Gamisch, Yannick M. Staedler, Jürg Schönenberger, Gunter A. Fischer, Hans Peter ComesAbstract:Sections were taken between the center and periphery of the Rostellum, and stained with ruthenium red/toluidine blue. In (A), red stained mucilage is visible only at the base of the stigmatic cavity and the adjacent stylar canal region (arrows), while in (B) it covers the entire stigmatic cavity (arrows) and extends throughout the non-vascularized, (semi-) lateral and rear (adaxial) parts of the Rostellum (black rectangle), where pollen tube growth apparently takes place (see Figure 4B, F, G). Abbreviations: c, column; dr, ‘displaced’ (suberect) Rostellum; e, elongate and loosely arranged cells of the stigma and (adaxial) parts of the Rostellum; p, pollinium; r, Rostellum; s, stigmatic cavity; sc, stylar canal; sr, rim of stigmatic cavity; v, viscidium. Scale bars: (A, B) = 0.1 mm.
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Longitudinal sections through the gynostemium apex of an auto-pollinated flower of Bulbophyllum bicoloratum.
2013Co-Authors: Alexander Gamisch, Yannick M. Staedler, Jürg Schönenberger, Gunter A. Fischer, Hans Peter ComesAbstract:Virtual micro-CT sections (slice thickness = 66.5 µm) were taken along the central (A), ‘intermediate’ (B), and peripheral (C) planes, approximately corresponding to the dashed lines of planes 1–3 in Figure 2E (see also corresponding scan-frames 1175/1892, 1049/1892 and 710/1892 in Video S3). (D–H) Corresponding longitudinal semithin sections through the Rostellum along its (D) near-central plane 1 (detailed in E), (F) ‘intermediate’ plane 2 (detailed in G), and (H) peripheral plane 3, and stained with ruthenium red/toluidine blue. The white dashed rectangles [D*] and [F*] in (A) and (B) indicate the approximate positions of the histological sections depicted in (D) and (F), respectively. Note pollen tubes growing through both the non-vascularized, (semi-) lateral parts of the Rostellum (see arrows in B, F and G) and the (semi-) lateral rims of the stigmatic cavity (B, C and H). See text for further details. Abbreviations: c, column; dr, ‘displaced’ (suberect) Rostellum; dv, detached viscidium tissue (possibly artifact); e, elongate and loosely arranged cells of the stigma; ip, inner pollinium; op, outer pollinium; p, pollinium; pt, pollen tubes; s, stigmatic cavity; sc, stylar canal; sr, rim of stigmatic cavity; v, viscidium; vb, vascular bundle. Scale bars: (D, F, H) = 0.05 mm; (E, G) = 0.01 mm.
Buga Sergey - One of the best experts on this subject based on the ideXlab platform.
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FIGURE 2 in The taxonomic status of Aphis Rostellum (Zhang, Chen, Zhong & Li, 1999) and description of the fundatrix and sexual morphs of Aphis umbrella (Börner, 1950) (Hemiptera: Aphidoidea)
2017Co-Authors: Stekolshchikov Andrey, Buga SergeyAbstract:FIGURE 2. Range of values of ratio of length of the ultimate rostral segment to length of 2nd segment of hind tarsus of apterous viviparous females in different geographic populations of Aphis umbrella (Börner, 1950) and A. Rostellum (Zhang, Chen, Zhong & Li, 1999)
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The taxonomic status of Aphis Rostellum (Zhang, Chen, Zhong & Li, 1999) and description of the fundatrix and sexual morphs of Aphis umbrella (Börner, 1950) (Hemiptera: Aphidoidea)
2017Co-Authors: Stekolshchikov Andrey, Buga SergeyAbstract:Stekolshchikov, Andrey V., Buga, Sergey V. (2017): The taxonomic status of Aphis Rostellum (Zhang, Chen, Zhong & Li, 1999) and description of the fundatrix and sexual morphs of Aphis umbrella (Börner, 1950) (Hemiptera: Aphidoidea). Zootaxa 4347 (3): 543-552, DOI: https://doi.org/10.11646/zootaxa.4347.3.
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FIGURE 3 in The taxonomic status of Aphis Rostellum (Zhang, Chen, Zhong & Li, 1999) and description of the fundatrix and sexual morphs of Aphis umbrella (Börner, 1950) (Hemiptera: Aphidoidea)
2017Co-Authors: Stekolshchikov Andrey, Buga SergeyAbstract:FIGURE 3. Scatter plot of length of the ultimate rostral segment against length of 2nd segment of hind tarsus of apterous viviparous female in different geographic populations of Aphis umbrella (Börner, 1950) and A. Rostellum (Zhang, Chen, Zhong & Li, 1999) (●—England; ○—France; □—Croatia; ♦—Belarus; ◊—Israel; —Russia, Belgorod and Russia, Astrakhan; ■— Iran; ▲—Tashkent; —Altai Republic
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FIGURE 1 in The taxonomic status of Aphis Rostellum (Zhang, Chen, Zhong & Li, 1999) and description of the fundatrix and sexual morphs of Aphis umbrella (Börner, 1950) (Hemiptera: Aphidoidea)
2017Co-Authors: Stekolshchikov Andrey, Buga SergeyAbstract:FIGURE 1. Length of ultimate rostrum segment of apterous viviparous female in different geographic populations of Aphis umbrella (Börner, 1950) and A. Rostellum (Zhang, Chen, Zhong & Li, 1999) (N-number of specimens) (England (N=7); France (N=3); Croatia (N=4); Belarus (N=44); Israel (N=1); Russia, Belgorod (N=1) and Russia, Astrakhan (N=8); Iran (N=2); Tashkent (N=5); Altai Republic (N=4)
Alexander Gamisch - One of the best experts on this subject based on the ideXlab platform.
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Multiple independent origins of auto-pollination in tropical orchids (Bulbophyllum) in light of the hypothesis of selfing as an evolutionary dead end
BMC Evolutionary Biology, 2015Co-Authors: Alexander Gamisch, Gunter Alexander Fischer, Hans Peter ComesAbstract:Background The transition from outcrossing to selfing has long been portrayed as an ‘evolutionary dead end’ because, first, reversals are unlikely and, second, selfing lineages suffer from higher rates of extinction owing to a reduced potential for adaptation and the accumulation of deleterious mutations. We tested these two predictions in a clade of Madagascan Bulbophyllum orchids (30 spp.), including eight species where auto-pollinating morphs (i.e., selfers, without a ‘Rostellum’) co-exist with their pollinator-dependent conspecifics (i.e., outcrossers, possessing a Rostellum). Specifically, we addressed this issue on the basis of a time-calibrated phylogeny by means of ancestral character reconstructions and within the state-dependent evolution framework of BiSSE (Binary State Speciation and Extinction), which allowed jointly estimating rates of transition, speciation, and extinction between outcrossing and selfing. Results The eight species capable of selfing occurred in scattered positions across the phylogeny, with two likely originating in the Pliocene (ca. 4.4–3.1 Ma), one in the Early Pleistocene (ca. 2.4 Ma), and five since the mid-Pleistocene (ca. ≤ 1.3 Ma). We infer that this scattered phylogenetic distribution of selfing is best described by models including up to eight independent outcrossing-to-selfing transitions and very low rates of speciation (and either moderate or zero rates of extinction) associated with selfing. Conclusions The frequent and irreversible outcrossing-to-selfing transitions in Madagascan Bulbophyllum are clearly congruent with the first prediction of the dead end hypothesis. The inability of our study to conclusively reject or support the likewise predicted higher extinction rate in selfing lineages might be explained by a combination of methodological limitations (low statistical power of our BiSSE approach to reliably estimate extinction in small-sized trees) and evolutionary processes (insufficient time elapsed for selfers to go extinct). We suggest that, in these tropical orchids, a simple genetic basis of selfing (via loss of the ‘Rostellum’) is needed to explain the strikingly recurrent transitions to selfing, perhaps reflecting rapid response to parallel and novel selective environments over Late Quaternary (≤ 1.3 Ma) time scales.
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histological and micro ct evidence of stigmatic Rostellum receptivity promoting auto pollination in the madagascan orchid bulbophyllum bicoloratum
PLOS ONE, 2013Co-Authors: Alexander Gamisch, Yannick M. Staedler, Jürg Schönenberger, Gunter A. Fischer, Hans Peter ComesAbstract:Background The Rostellum, a projecting part of the gynostemium in orchid flowers, separates the anther(s) from the stigma and thus commonly prevents auto-pollination. Nonetheless, as a modified (usually distal) portion of the median stigma lobe, the Rostellum has been frequently invoked of having re-gained a stigmatic function in rare cases of orchid auto-pollination. Here it is shown that a newly discovered selfing variant of Madagascan Bulbophyllumbicoloratum has evolved a modified Rostellum allowing the penetration of pollen tubes from in situ pollinia.
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Apical gynostemium structures of Bulbophyllum bicoloratum viewed under the stereomicroscope (A, B) and scanning electron microscope (C–E).
2013Co-Authors: Alexander Gamisch, Yannick M. Staedler, Jürg Schönenberger, Gunter A. Fischer, Hans Peter ComesAbstract:(A) Isolated column of an outcrossing individual with erect Rostellum at anthesis (without pollinia); (B) isolated column of a selfing individual with ‘displaced’ (suberect) Rostellum at pre-anthesis (note, at anthesis, swollen pollina will obstruct the view on the Rostellum; compare E); (C) column of a selfing individual with pollinia still in the anther at pre-anthesis; (D) close-up of the ‘displaced’ (suberect) Rostellum (same as C) with the viscidium at its apex and cuticular folds on the upper (adaxial) side (except for the lateral sides); (E) column of a selfing individual after pollinia have been released from the anther onto the ‘displaced’ (suberect) Rostellum. The swollen outer pollinia contact the (semi-) lateral rims of the stigmatic cavity (arrow). The dashed lines of planes 1–3 indicate approximate positions of longitudinal micro-CT sections shown in Figure 4A–C, respectively. The arrow below indicates the directionality of the complete scan (see Video S3), with numbers identifying scan-frames roughly corresponding to planes 1–3. Abbreviations: a, anther; c, column (gynostemium); dr, ‘displaced’ (suberect) Rostellum (with cuticular folding); lr, lateral sides of ‘displaced’ (suberect) Rostellum (devoid of cuticular folding); p, pollinia; ip, inner pollinium; op, outer pollinium; r, Rostellum; s, stigmatic cavity; sr, rim of stigmatic cavity; st, stelidium; v, viscidium. Scale bars: (A, B) = 0.5 mm; (C, E) = 0.2 mm; (D) = 0.1 mm.
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Longitudinal semithin sections through the stigmatic cavity and Rostellum of an outcrosser (A) and selfer (B) of Bulbophyllum bicoloratum.
2013Co-Authors: Alexander Gamisch, Yannick M. Staedler, Jürg Schönenberger, Gunter A. Fischer, Hans Peter ComesAbstract:Sections were taken between the center and periphery of the Rostellum, and stained with ruthenium red/toluidine blue. In (A), red stained mucilage is visible only at the base of the stigmatic cavity and the adjacent stylar canal region (arrows), while in (B) it covers the entire stigmatic cavity (arrows) and extends throughout the non-vascularized, (semi-) lateral and rear (adaxial) parts of the Rostellum (black rectangle), where pollen tube growth apparently takes place (see Figure 4B, F, G). Abbreviations: c, column; dr, ‘displaced’ (suberect) Rostellum; e, elongate and loosely arranged cells of the stigma and (adaxial) parts of the Rostellum; p, pollinium; r, Rostellum; s, stigmatic cavity; sc, stylar canal; sr, rim of stigmatic cavity; v, viscidium. Scale bars: (A, B) = 0.1 mm.
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Longitudinal sections through the gynostemium apex of an auto-pollinated flower of Bulbophyllum bicoloratum.
2013Co-Authors: Alexander Gamisch, Yannick M. Staedler, Jürg Schönenberger, Gunter A. Fischer, Hans Peter ComesAbstract:Virtual micro-CT sections (slice thickness = 66.5 µm) were taken along the central (A), ‘intermediate’ (B), and peripheral (C) planes, approximately corresponding to the dashed lines of planes 1–3 in Figure 2E (see also corresponding scan-frames 1175/1892, 1049/1892 and 710/1892 in Video S3). (D–H) Corresponding longitudinal semithin sections through the Rostellum along its (D) near-central plane 1 (detailed in E), (F) ‘intermediate’ plane 2 (detailed in G), and (H) peripheral plane 3, and stained with ruthenium red/toluidine blue. The white dashed rectangles [D*] and [F*] in (A) and (B) indicate the approximate positions of the histological sections depicted in (D) and (F), respectively. Note pollen tubes growing through both the non-vascularized, (semi-) lateral parts of the Rostellum (see arrows in B, F and G) and the (semi-) lateral rims of the stigmatic cavity (B, C and H). See text for further details. Abbreviations: c, column; dr, ‘displaced’ (suberect) Rostellum; dv, detached viscidium tissue (possibly artifact); e, elongate and loosely arranged cells of the stigma; ip, inner pollinium; op, outer pollinium; p, pollinium; pt, pollen tubes; s, stigmatic cavity; sc, stylar canal; sr, rim of stigmatic cavity; v, viscidium; vb, vascular bundle. Scale bars: (D, F, H) = 0.05 mm; (E, G) = 0.01 mm.
