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Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae)

Floral nectaries are closely associated with biotic pollination, and the nectar produced by corolla nectaries is generally enclosed in floral structures. Although some Swertia spp. (Gentianaceae), including S. bimaculata, evolved a peculiar form of corolla nectaries (known as “gland patches”) arrang...

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Autores principales: Wang, Shuai, Fu, Wen‐Long, Du, Wei, Zhang, Qi, Li, Ya, Lyu, Yu‐Shu, Wang, Xiao‐Fan
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5869268/
https://www.ncbi.nlm.nih.gov/pubmed/29607017
http://dx.doi.org/10.1002/ece3.3838
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author Wang, Shuai
Fu, Wen‐Long
Du, Wei
Zhang, Qi
Li, Ya
Lyu, Yu‐Shu
Wang, Xiao‐Fan
author_facet Wang, Shuai
Fu, Wen‐Long
Du, Wei
Zhang, Qi
Li, Ya
Lyu, Yu‐Shu
Wang, Xiao‐Fan
author_sort Wang, Shuai
collection PubMed
description Floral nectaries are closely associated with biotic pollination, and the nectar produced by corolla nectaries is generally enclosed in floral structures. Although some Swertia spp. (Gentianaceae), including S. bimaculata, evolved a peculiar form of corolla nectaries (known as “gland patches”) arranged in a conspicuous ring on the rotate corolla and that completely expose their nectar, little is known about the pollination of these plants. Two hypotheses were made concerning the possible effects of gland patches: visual attraction and visitor manipulation. The floral traits, mating system, and insect pollination of S. bimaculata were examined, and the pollination effects of gland patches were evaluated. A comparative study was made using Swertia kouitchensis, a species with fimbriate nectaries. Swertia bimaculata flowers were protandrous, with obvious stamen movement leading to herkogamy in the female phase and to a significant reduction in nectary–anther distance. The species is strongly entomophilous and facultatively xenogamous. The daily reward provided per flower decreased significantly after the male phase. The most effective pollinators were large dipterans, and the visiting proportion of Diptera was significantly higher in S. bimaculata than in S. kouitchensis. Most visitors performed “circling behavior” in S. bimaculata flowers. Removing or blocking the nectaries caused no reduction in visiting frequency but a significant reduction in visit duration, interrupting the circling behavior. The circling behavior was encouraged by nectar abundance and promoted pollen dispersal. Visitor species with small body size had little chance to contact the anthers or stigma, revealing a filtration effect exerted by the floral design. These results rejected the “visual attraction” hypothesis and supported the “visitor manipulation” hypothesis. The nectary whorl within a flower acted like a ring‐shaped track that urged nectar foragers to circle on the corolla, making pollination in S. bimaculata flowers more orderly and selective than that in classically generalist flowers.
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spelling pubmed-58692682018-03-30 Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae) Wang, Shuai Fu, Wen‐Long Du, Wei Zhang, Qi Li, Ya Lyu, Yu‐Shu Wang, Xiao‐Fan Ecol Evol Original Research Floral nectaries are closely associated with biotic pollination, and the nectar produced by corolla nectaries is generally enclosed in floral structures. Although some Swertia spp. (Gentianaceae), including S. bimaculata, evolved a peculiar form of corolla nectaries (known as “gland patches”) arranged in a conspicuous ring on the rotate corolla and that completely expose their nectar, little is known about the pollination of these plants. Two hypotheses were made concerning the possible effects of gland patches: visual attraction and visitor manipulation. The floral traits, mating system, and insect pollination of S. bimaculata were examined, and the pollination effects of gland patches were evaluated. A comparative study was made using Swertia kouitchensis, a species with fimbriate nectaries. Swertia bimaculata flowers were protandrous, with obvious stamen movement leading to herkogamy in the female phase and to a significant reduction in nectary–anther distance. The species is strongly entomophilous and facultatively xenogamous. The daily reward provided per flower decreased significantly after the male phase. The most effective pollinators were large dipterans, and the visiting proportion of Diptera was significantly higher in S. bimaculata than in S. kouitchensis. Most visitors performed “circling behavior” in S. bimaculata flowers. Removing or blocking the nectaries caused no reduction in visiting frequency but a significant reduction in visit duration, interrupting the circling behavior. The circling behavior was encouraged by nectar abundance and promoted pollen dispersal. Visitor species with small body size had little chance to contact the anthers or stigma, revealing a filtration effect exerted by the floral design. These results rejected the “visual attraction” hypothesis and supported the “visitor manipulation” hypothesis. The nectary whorl within a flower acted like a ring‐shaped track that urged nectar foragers to circle on the corolla, making pollination in S. bimaculata flowers more orderly and selective than that in classically generalist flowers. John Wiley and Sons Inc. 2018-02-19 /pmc/articles/PMC5869268/ /pubmed/29607017 http://dx.doi.org/10.1002/ece3.3838 Text en © 2018 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Research
Wang, Shuai
Fu, Wen‐Long
Du, Wei
Zhang, Qi
Li, Ya
Lyu, Yu‐Shu
Wang, Xiao‐Fan
Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae)
title Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae)
title_full Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae)
title_fullStr Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae)
title_full_unstemmed Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae)
title_short Nectary tracks as pollinator manipulators: The pollination ecology of Swertia bimaculata (Gentianaceae)
title_sort nectary tracks as pollinator manipulators: the pollination ecology of swertia bimaculata (gentianaceae)
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5869268/
https://www.ncbi.nlm.nih.gov/pubmed/29607017
http://dx.doi.org/10.1002/ece3.3838
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