J Plant Ecol ›› 2017, Vol. 10 ›› Issue (4): 634-648.doi: 10.1093/jpe/rtw068

• Research Articles • Previous Articles     Next Articles

The role of the pollination niche in community assembly of Erica species in a biodiversity hotspot

Roderick W. Bouman1,2,3, Sandy-Lynn Steenhuisen4 and Timotheüs van der Niet1,2,5,*   

  1. 1 Naturalis Biodiversity Center, Understanding Evolution Group, Darwinweg 4, 2333 CR Leiden, The Netherlands; 2 Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands; 3 Hortus Botanicus Leiden, 5e Binnenvestgracht 8, 2311 VH Leiden, The Netherlands; 4 Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa; 5 School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa
  • Received:2015-09-30 Accepted:2016-06-19 Online:2016-06-27 Published:2017-07-24
  • Contact: van der Niet, Timotheus E-mail:vdniet@gmail.com

Abstract: Aims Closely related species frequently co-occur in plant communities. The role of niche partitioning for allowing their coexistence has been called into question, but most studies on community ecology neglect pollination as a niche component, and thus potentially underestimate niche partitioning. Here, we investigate the importance of the pollination niche for determining coexistence in a biodiversity hotspot. We specifically test whether co-flowering insect-pollinated species of Erica, the most species-rich plant genus of the South African Cape Floristic Region, are characterized by different functional floral traits and different specialized pollination systems.
Methods Communities of co-flowering Erica species were studied at three sites in the fynbos biome in the Western Cape of South Africa. We focused on five species with flowers that conform to an insect pollination syndrome. We assessed whether floral traits important for pollinator attraction and mechanical fit overlap by comparison of scent (gas chromatography coupled with mass spectrometry), colour (spectrophotometry and models of bee vision), nectar volume and concentration and corolla morphology. Pollinator partitioning was quantified by comparison of floral visitor profiles and pollinator importance, calculated as the product of visitation rate, number of flowers probed per visit and pollen load for each functional visitor group among species within communities. Potential effects of competition were assessed by comparing visitation rates both directly and using anther ring disturbance as a proxy for lifetime visitation.
Important findings Floral phenotypes differed among species within communities in all functional traits. Visitor assemblages were diverse, including ants, beetles, flies, honeybees, moths and solitary bees. However, the Cape honeybee, Apis mellifera capensis, was the main pollinator of all but one Erica species. Insect visitation rates were significantly lower for E. imbricata and E. calycina relative to congeners, but high rates of anther ring disturbance, which differed significantly in only two out of seven comparisons, suggest that long-term visitation rates are mostly similar among species that share pollinators. This study shows that coexistence of co-flowering insect-pollinated Erica species is not determined by specialization for different pollination systems. Pollinator sharing might rather lead to facilitation among co-flowering species, and floral constancy mediated by extensive interspecific floral trait variation might mitigate its potentially negative effects.

Key words: Cape Floristic Region, coexistence, floral traits, heaths, pollination niche

摘要:
Aims Closely related species frequently co-occur in plant communities. The role of niche partitioning for allowing their coexistence has been called into question, but most studies on community ecology neglect pollination as a niche component, and thus potentially underestimate niche partitioning. Here, we investigate the importance of the pollination niche for determining coexistence in a biodiversity hotspot. We specifically test whether co-flowering insect-pollinated species of Erica, the most species-rich plant genus of the South African Cape Floristic Region, are characterized by different functional floral traits and different specialized pollination systems.
Methods Communities of co-flowering Erica species were studied at three sites in the fynbos biome in the Western Cape of South Africa. We focused on five species with flowers that conform to an insect pollination syndrome. We assessed whether floral traits important for pollinator attraction and mechanical fit overlap by comparison of scent (gas chromatography coupled with mass spectrometry), colour (spectrophotometry and models of bee vision), nectar volume and concentration and corolla morphology. Pollinator partitioning was quantified by comparison of floral visitor profiles and pollinator importance, calculated as the product of visitation rate, number of flowers probed per visit and pollen load for each functional visitor group among species within communities. Potential effects of competition were assessed by comparing visitation rates both directly and using anther ring disturbance as a proxy for lifetime visitation.
Important findings Floral phenotypes differed among species within communities in all functional traits. Visitor assemblages were diverse, including ants, beetles, flies, honeybees, moths and solitary bees. However, the Cape honeybee, Apis mellifera capensis, was the main pollinator of all but one Erica species. Insect visitation rates were significantly lower for E. imbricata and E. calycina relative to congeners, but high rates of anther ring disturbance, which differed significantly in only two out of seven comparisons, suggest that long-term visitation rates are mostly similar among species that share pollinators. This study shows that coexistence of co-flowering insect-pollinated Erica species is not determined by specialization for different pollination systems. Pollinator sharing might rather lead to facilitation among co-flowering species, and floral constancy mediated by extensive interspecific floral trait variation might mitigate its potentially negative effects.

[1] Xiao-Yue Wang, Qiu-Mei Quan, Bo Wang, Yun-Xiang Li, Shuang-Quan Huang. Discovery of androecium color polymorphism in Epimedium pubescens with habitat preference of anther/pollen color in the genus [J]. J Plant Ecol, 2018, 11(4): 533-541.
[2] Jaime Madrigal-González, Rodrigo S. Rios, Cristina F. Aragón, Ernesto Gianoli. Indirect facilitation by a liana might explain the dominance of a small tree in a temperate forest [J]. J Plant Ecol, 2018, 11(4): 604-612.
[3] Hai-Dong Li, Yan-Hui Zhao, Zong-Xin Ren, Zhi-Kun Wu, Lorne M. Wolfe, Peter Bernhardt, Hong Wang. Fitness-related selection on floral traits in the distylous plant Primula poissonii (Primulaceae) [J]. J Plant Ecol, 2017, 10(3): 559-568.
[4] Junmeng Lu, Daniel J. Johnson, Xiujuan Qiao, Zhijun Lu, Qinggang Wang, Mingxi Jiang. Density dependence and habitat preference shape seedling survival in a subtropical forest in central China [J]. J Plant Ecol, 2015, 8(6): 568-577.
[5] Ai-Qin Zhang, Shuang He, Ya-Xin Zhai, Shuang-Quan Huang. Does persistence of showy calyces in Limonium leptolobum enhance pollinator attraction? [J]. J Plant Ecol, 2015, 8(2): 182-186.
[6] Nicholas A. Barber, Nicole L. Soper Gorden. How do belowground organisms influence plant-pollinator interactions? [J]. J Plant Ecol, 2015, 8(1): 1-11.
[7] Richard P. Kipling, John Warren. How generalists coexist: the role of floral phenotype and spatial factors in the pollination systems of two Ranunculus species [J]. J Plant Ecol, 2014, 7(5): 480-489.
[8] Zhonghua Zhang, Gang Hu, Jiedong Zhu, Jian Ni. Aggregated spatial distributions of species in a subtropical karst forest, southwestern China [J]. J Plant Ecol, 2013, 6(2): 131-140.
[9] Youshi Wang, M. D. Farnon Ellwood, Fernando T. Maestre, Zhiyong Yang, Gang Wang, Chengjin Chu. Positive interactions can produce species-rich communities and increase species turnover through time [J]. J Plant Ecol, 2012, 5(4): 417-421.
[10] Fangliang He, Da-Yong Zhang, Kui Lin. Coexistence of nearly neutral species [J]. J Plant Ecol, 2012, 5(1): 72-81.
[11] Da-Yong Zhang, Bo-Yu Zhang, Kui Lin, Xinhua Jiang, Yi Tao, Stephen Hubbell, Fangliang He, Annette Ostling. Demographic trade-offs determine species abundance and diversity [J]. J Plant Ecol, 2012, 5(1): 82-88.
[12] Amanda J. Tracey, Lonnie W. Aarssen. Competition and body size in plants: the between-species trade-off for maximum potential versus minimum reproductive threshold size [J]. J Plant Ecol, 2011, 4(3): 115-122.
Viewed
Full text


Abstract

Cited

  Shared   
  Discussed   
[1] Cui Gao;Yuxia Chen;Ying Bao;Min Feng;Anming Lu. Studies on Sexual Organs and Embryological Development Morphology of Speirantha gardenii (Convallariaceae)[J]. Chin Bull Bot, 2010, 45(06): 705 -712 .
[2] Jiang Gao-ming. The Impact of Globae Increasing of CO2 on Plants[J]. Chin Bull Bot, 1995, 12(04): 1 -7 .
[3] Zhang Jun Han Bi-wen. Advance in the Study of Histochemical Localization for[J]. Chin Bull Bot, 1995, 12(专辑3): 131 -142 .
[4] Tang Yan-cheng. A Short Guide to the International Code of Botanical Nomenclature V.[J]. Chin Bull Bot, 1984, 2(04): 51 -57 .
[5] Xu Ji. The Protective Protein of Nitrogenase Against Oxygen Damage-Fe-S Protein[J]. Chin Bull Bot, 1986, 4(12): 1 -4 .
[6] . [J]. Chin Bull Bot, 2001, 18(05): 633 .
[7] Huang Zhao-xiang;Zheng Zhen-gui and Zhu Du. Ecological Effect of Taxodium ascendens-Oryza sativa Ecosystem(I) The Growing Characteristic of Taxodium Ascendens in the Ecosystem[J]. Chin Bull Bot, 1996, 13(02): 48 -51 .
[8] GU Rui-Sheng;LIU Qun-Lu;CHEN Xue-Mei and JIANG Xiang-Ning. Comparison and Optimization of the Methods on Protein Extraction and SDS-PAGE in Woody Plants[J]. Chin Bull Bot, 1999, 16(02): 171 -177 .
[9] Jiang Gao-ming. LI-6400 Portable Photosynthesis System: Principle, Function, Basic Operation and Main Problems and Solutions During Measurement[J]. Chin Bull Bot, 1996, 13(增刊): 72 -76 .
[10] Li Ling;Luo Yun-xiu;He Jian-hui and Pan Rui-chi. Promoting the Formation of Adventitious Roots in Cutting of Some Woody Plants by GL Reagent[J]. Chin Bull Bot, 1996, 13(增刊): 63 -65 .