1
|
van Welzen PC, Winkel E, Bouman RW. Parallel developments in floral adaptations to obligate moth pollination mutualism in tribe Phyllantheae (Phyllanthaceae). PHYTOKEYS 2023; 225:165-198. [PMID: 37179576 PMCID: PMC10170313 DOI: 10.3897/phytokeys.225.99506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 03/21/2023] [Indexed: 05/15/2023]
Abstract
Several groups within tribe Phyllantheae (Phyllanthaceae) formed, independently, an (obligate) pollination mutualism with Epicephala moths, which originally had been parasitic. In this pollination system, female moths actively collect pollen from staminate flowers and deposit it on the stigma of pistillate flowers, after which they place at least one egg in or against the ovary. The high pollination rate makes the system beneficial for the plants, whereas the larvae are provided with food (part of the developing seeds) and some protection against predation. Qualitative comparisons are made between non-moth-pollinated lineages, used as outgroups and various, independently moth-pollinated Phyllantheae clades, used as ingroups, thereby looking for parallel developments. The flowers of both sexes of various groups display similar, convergent morphological adaptations to the pollination system, likely to secure the obligate relationship and to improve efficiency. Sepals in both sexes, free or partly to highly connate, are commonly upright and form a narrow tube. The staminate flowers often have united, vertical stamens with the anthers along the androphore or on top of the androphore. Pistillate flowers generally reduce the stigmatic surface, either by making the stigmas shorter or by uniting them into a cone with a small opening at the top for pollen deposition. Less obvious is the reduction of the stigmatic papillae; these are often present in non-moth-pollinated taxa, but absent in the moth-pollinated species. The most diverging, parallel adaptations to moth pollination are currently found in the Palaeotropics, whereas in the Neotropics, some groups continue to also be pollinated by other insect groups and are morphologically less changed.
Collapse
Affiliation(s)
- Peter C. van Welzen
- Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, Netherlands
- Institute of Biology Leiden, Leiden University, PO Box 9505, 2300 RA Leiden, Netherlands
| | - Esmée Winkel
- Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, Netherlands
| | - Roderick W. Bouman
- Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, Netherlands
- Institute of Biology Leiden, Leiden University, PO Box 9505, 2300 RA Leiden, Netherlands
| |
Collapse
|
2
|
Xie H, Yang P, Xia Y, Kjellberg F, Darwell CT, Li ZB. Maintenance of specificity in sympatric host-specific fig/wasp pollination mutualisms. PeerJ 2022; 10:e13897. [PMID: 35975234 PMCID: PMC9375967 DOI: 10.7717/peerj.13897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/22/2022] [Indexed: 01/19/2023] Open
Abstract
Background Fig/wasp pollination mutualisms are extreme examples of species-specific plant-insect symbioses, but incomplete specificity occurs, with potentially important evolutionary consequences. Why pollinators enter alternative hosts, and the fates of pollinators and the figs they enter, are unknown. Methods We studied the pollinating fig wasp, Ceratosolen emarginatus, which concurrently interacts with its typical host Ficus auriculata and the locally sympatric alternative host F. hainanensis, recording frequencies of the wasp in figs of the alternative hosts. We measured ovipositor lengths of pollinators and style lengths in female and male figs in the two host species. Volatile organic compounds (VOCs) emitted by receptive figs of each species were identified using GC-MS. We tested the attraction of wasps to floral scents in choice experiments, and detected electrophysiologically active compounds by GC-EAD. We introduced C. emarginatus foundresses into figs of both species to reveal the consequences of entry into the alternative host. Results C. emarginatus entered a low proportion of figs of the alternative host, and produced offspring in a small proportion of them. Despite differences in the VOC profiles of the two fig species, they included shared semiochemicals. Although C. emarginatus females prefer receptive figs of F. auriculata, they are also attracted to those of F. hainanensis. C. emarginatus that entered male figs of F. hainanensis produced offspring, as their ovipositors were long enough to reach the bottom of the style; however, broods were larger and offspring smaller than in the typical host. Female figs of F. hainanensis failed to produce seeds when visited by C. emarginatus. These findings advance our current understanding of how these species-specific mutualisms usually remain stable and the conditions that allow their diversification.
Collapse
Affiliation(s)
- Hua Xie
- Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China, Southwest Forestry University, Kunming, Yunnan, China
| | - Pei Yang
- Yunnan University of Chinese Medicine, Kunming, Yunnan, China
| | - Yan Xia
- Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China, Southwest Forestry University, Kunming, Yunnan, China
| | - Finn Kjellberg
- CEFE, CNRS, Université de Montpellier, EPHE, IRD, Montpellier, France
| | - Clive T. Darwell
- Biodiversity and Biocomplexity Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Zong-Bo Li
- Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China, Southwest Forestry University, Kunming, Yunnan, China
| |
Collapse
|
3
|
Chheang P, Hembry DH, Yao G, Luo SX. Diversity and species-specificity of brood pollination of leafflower trees (Phyllanthaceae: Glochidion) by leafflower moths (Lepidoptera: Epicephala) in tropical Southeast Asia (Cambodia). PLANT DIVERSITY 2022; 44:191-200. [PMID: 35505992 PMCID: PMC9043405 DOI: 10.1016/j.pld.2021.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 06/18/2021] [Accepted: 07/01/2021] [Indexed: 06/14/2023]
Abstract
Glochidion (Phyllanthaceae; leafflower trees) is a genus of trees which is widely reported to be pollinated by leafflower moths (Gracillariidae: Epicephala) in temperate and subtropical Asia, Australia, and the Pacific islands. However, the pollination ecology of Glochidion is not well described from tropical Asia, the region where it is most species-rich at both local (≤9 spp.) and regional (~200 spp.) scales. Here we report investigations of pollination biology and species-specificity of five Glochidion species in tropical Southeast Asia (Cambodia). Through nocturnal observations and fruit dissections, we find that at least three and likely five Glochidion species in Cambodia are pollinated by seed-parasitic leafflower moths. We find no evidence that any of these leafflower moths are non-mutualistic parasites, despite known examples of such parasites of this mutualism elsewhere in Asia. While the presence of a single larva in a fruit results in only a fraction of seeds being consumed, the presence of more than one larva per fruit-a frequent occurrence in some species-can result in almost all seeds within the fruit being infested. Multilocus phylogenetic analysis indicates that there are five different minimally monophyletic leafflower moth clades, each of which pollinates a unique Glochidion host species. Our results indicate that in its center of diversity in tropical Asia this system is an obligate pollination mutualism as previously described at the global margins of its distribution. These findings provide insights into the processes that generate and maintain biodiversity and maintain mutualism stability in plant-insect interactions in this biodiversity hotspot.
Collapse
Affiliation(s)
- Pisal Chheang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Yuquanlu, 19A, Beijing, 100049, China
- National Authority for Preah Vihear, Choam Khsant, 13403, Cambodia
| | - David H. Hembry
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Gang Yao
- South China Limestone Plants Research Centre, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Shi-Xiao Luo
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| |
Collapse
|
4
|
Salzman S, Crook D, Calonje M, Stevenson DW, Pierce NE, Hopkins R. Cycad-Weevil Pollination Symbiosis Is Characterized by Rapidly Evolving and Highly Specific Plant-Insect Chemical Communication. FRONTIERS IN PLANT SCIENCE 2021; 12:639368. [PMID: 33995438 PMCID: PMC8121082 DOI: 10.3389/fpls.2021.639368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/12/2021] [Indexed: 06/12/2023]
Abstract
Coevolution between plants and insects is thought to be responsible for generating biodiversity. Extensive research has focused largely on antagonistic herbivorous relationships, but mutualistic pollination systems also likely contribute to diversification. Here we describe an example of chemically-mediated mutualistic species interactions affecting trait evolution and lineage diversification. We show that volatile compounds produced by closely related species of Zamia cycads are more strikingly different from each other than are other phenotypic characters, and that two distantly related pollinating weevil species have specialized responses only to volatiles from their specific host Zamia species. Plant transcriptomes show that approximately a fifth of genes related to volatile production are evolving under positive selection, but we find no differences in the relative proportion of genes under positive selection in different categories. The importance of phenotypic divergence coupled with chemical communication for the maintenance of this obligate mutualism highlights chemical signaling as a key mechanism of coevolution between cycads and their weevil pollinators.
Collapse
Affiliation(s)
- Shayla Salzman
- Plant Sciences, Cornell University, Ithaca, NY, United States
- Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | - Damon Crook
- Otis Laboratory, USDA-APHIS-PPQ CPHST, Otis ANGB, MA, United States
| | - Michael Calonje
- Montgomery Botanical Center, Coral Gables, FL, United States
| | | | - Naomi E. Pierce
- Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | - Robin Hopkins
- Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
| |
Collapse
|
5
|
Wang Z, Yang X, Zhang Z, Shi F, Li H. Multiple Coexisting Species and the First Known Case of a Cheater in Epicephala (Gracillariidae) Associated with a Species of Glochidion (Phyllanthaceae) in Tropical Asia. JOURNAL OF INSECT SCIENCE (ONLINE) 2020; 20:5897084. [PMID: 32841344 PMCID: PMC7447135 DOI: 10.1093/jisesa/ieaa081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Indexed: 05/27/2023]
Abstract
Glochidion plants and Epicephala moths played different roles and kept the balance in the mutualism. We studied the four coexisting Epicephala species on Glochidion sphaerogynum in detail and reconstructed the phylogenic tree of 40 Gracillariidae species. The results showed that one of them (Epicephala impolliniferens) did not pollinate G. sphaerogynum, because of lacking the specialized structure of carrying pollen. These results suggested that E. impolliniferens acted as a 'cheater' in the system. The phylogenetic analyses suggested that E. impolliniferens derived from a pollinating species, and had secondarily gave up the ability to pollinate. This is a typical phenomenon of mutualism reversal. The phenomenon exhibits the co-evolutionary diversification under selection pressures.
Collapse
Affiliation(s)
- Zhibo Wang
- College of Life Sciences, Nankai University, Tianjin, China
| | - Xiaofei Yang
- College of Life Sciences, Nankai University, Tianjin, China
| | - Zhenguo Zhang
- College of Life Sciences, Nankai University, Tianjin, China
| | - Fuchen Shi
- College of Life Sciences, Nankai University, Tianjin, China
| | - Houhun Li
- College of Life Sciences, Nankai University, Tianjin, China
| |
Collapse
|
6
|
Abbas F, Ke Y, Yu R, Yue Y, Amanullah S, Jahangir MM, Fan Y. Volatile terpenoids: multiple functions, biosynthesis, modulation and manipulation by genetic engineering. PLANTA 2017; 246:803-816. [PMID: 28803364 DOI: 10.1007/s00425-017-2749-x] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 07/22/2017] [Indexed: 05/18/2023]
Abstract
Terpenoids play several physiological and ecological functions in plant life through direct and indirect plant defenses and also in human society because of their enormous applications in the pharmaceutical, food and cosmetics industries. Through the aid of genetic engineering its role can by magnified to broad spectrum by improving genetic ability of crop plants, enhancing the aroma quality of fruits and flowers and the production of pharmaceutical terpenoids contents in medicinal plants. Terpenoids are structurally diverse and the most abundant plant secondary metabolites, playing an important role in plant life through direct and indirect plant defenses, by attracting pollinators and through different interactions between the plants and their environment. Terpenoids are also significant because of their enormous applications in the pharmaceutical, food and cosmetics industries. Due to their broad distribution and functional versatility, efforts are being made to decode the biosynthetic pathways and comprehend the regulatory mechanisms of terpenoids. This review summarizes the recent advances in biosynthetic pathways, including the spatiotemporal, transcriptional and post-transcriptional regulatory mechanisms. Moreover, we discuss the multiple functions of the terpene synthase genes (TPS), their interaction with the surrounding environment and the use of genetic engineering for terpenoid production in model plants. Here, we also provide an overview of the significance of terpenoid metabolic engineering in crop protection, plant reproduction and plant metabolic engineering approaches for pharmaceutical terpenoids production and future scenarios in agriculture, which call for sustainable production platforms by improving different plant traits.
Collapse
Affiliation(s)
- Farhat Abbas
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Yanguo Ke
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Rangcai Yu
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China.
| | - Yuechong Yue
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China
| | - Sikandar Amanullah
- College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin, Heilongjiang, China
| | | | - Yanping Fan
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China.
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangzhou, 510642, China.
| |
Collapse
|
7
|
Yoder JB, Tiffin P. Sanctions, Partner Recognition, and Variation in Mutualism. Am Nat 2017; 190:491-505. [DOI: 10.1086/693472] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
8
|
Farré-Armengol G, Filella I, Llusià J, Peñuelas J. β-Ocimene, a Key Floral and Foliar Volatile Involved in Multiple Interactions between Plants and Other Organisms. Molecules 2017; 22:molecules22071148. [PMID: 28703755 PMCID: PMC6152128 DOI: 10.3390/molecules22071148] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 07/03/2017] [Indexed: 01/24/2023] Open
Abstract
β-Ocimene is a very common plant volatile released in important amounts from the leaves and flowers of many plant species. This acyclic monoterpene can play several biological functions in plants, by potentially affecting floral visitors and also by mediating defensive responses to herbivory. The ubiquity and high relative abundance of β-ocimene in the floral scents of species from most plant families and from different pollination syndromes (ranging from generalism to specialism) strongly suggest that this terpenoid may play an important role in the attraction of pollinators to flowers. We compiled abundant evidence from published studies that supports β-ocimene as a generalist attractant of a wide spectrum of pollinators. We found no studies testing behavioural responses of pollinators to β-ocimene, that could directly demonstrate or deny the function of β-ocimene in pollinator attraction; but several case studies support that the emissions of β-ocimene in flowers of different species follow marked temporal and spatial patterns of emission, which are typical from floral volatile organic compound (VOC) emissions that are involved in pollinator attraction. Furthermore, important β-ocimene emissions are induced from vegetative plant tissues after herbivory in many species, which have relevant functions in the establishment of tritrophic interactions. We thus conclude that β-ocimene is a key plant volatile with multiple relevant functions in plants, depending on the organ and the time of emission. Experimental behavioural studies on pure β-ocimene conducted with pollinating insects will be necessary to prove the assumptions made here.
Collapse
Affiliation(s)
- Gerard Farré-Armengol
- CSIC, Global Ecology Unit CREAF-CSIC-UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain.
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain.
- Department of Ecology and Evolution, University of Salzburg, Hellbrunnerstraße 34, 5020 Salzburg, Austria.
| | - Iolanda Filella
- CSIC, Global Ecology Unit CREAF-CSIC-UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain.
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain.
| | - Joan Llusià
- CSIC, Global Ecology Unit CREAF-CSIC-UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain.
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain.
| | - Josep Peñuelas
- CSIC, Global Ecology Unit CREAF-CSIC-UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain.
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain.
| |
Collapse
|
9
|
Luo SX, Yao G, Wang Z, Zhang D, Hembry DH. A Novel, Enigmatic Basal Leafflower Moth Lineage Pollinating a Derived Leafflower Host Illustrates the Dynamics of Host Shifts, Partner Replacement, and Apparent Coadaptation in Intimate Mutualisms. Am Nat 2017; 189:422-435. [PMID: 28350503 DOI: 10.1086/690623] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Leafflower plant/leafflower moth brood pollination mutualisms are widespread in the Paleotropics. Leafflower moths pollinate leafflower plants, but their larvae consume a subset of the hosts' seeds. These interactions are highly phylogenetically constrained: six clades of leafflower plants are each associated with a unique clade of leafflower moths (Epicephala). Here, we report a previously unrecognized basal seventh pollinating Epicephala lineage-associated with the highly derived leafflower clade Glochidion-in Asia. Epicephala lanceolaria is a pollinator and seed predator of Glochidion lanceolarium. Phylogenetic inference indicates that the ancestor of E. lanceolaria most likely shifted onto the ancestor of G. lanceolarium and displaced the ancestral allospecific Epicephala pollinator in at least some host populations. The unusual and apparently coadapted aspects of the G. lanceolarium/E. lanceolaria reproductive cycles suggest that plant-pollinator coevolution may have played a role in this displacement and provide insights into the dynamics of host shifts and trait coevolution in this specialized mutualism.
Collapse
|
10
|
Wang G, Cannon CH, Chen J. Pollinator sharing and gene flow among closely related sympatric dioecious fig taxa. Proc Biol Sci 2016; 283:rspb.2015.2963. [PMID: 27075252 DOI: 10.1098/rspb.2015.2963] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/16/2016] [Indexed: 11/12/2022] Open
Abstract
Hybridization and insect pollination are widely believed to increase rates of plant diversification. The extreme diversity of figs (Ficus) and their obligate pollinators, fig wasps (Agaonidae), provides an opportunity to examine the possible role of pollinator-mediated hybridization in plant diversification. Increasing evidence suggests that pollinator sharing and hybridization occurs among fig taxa, despite relatively strict coevolution with the pollinating wasp. Using five sympatric dioecious fig taxa and their pollinators, we examine the degree of pollinator sharing and inter-taxa gene flow. We experimentally test pollinator preference for floral volatiles, the main host recognition signal, from different figs. All five fig taxa shared pollinators with other taxa, and gene flow occurred between fig taxa within and between sections. Floral volatiles of each taxon attracted more than one pollinator species. Floral volatiles were more similar between closely related figs, which experienced higher levels of pollinator sharing and inter-taxa gene flow. This study demonstrates that pollinator sharing and inter-taxa gene flow occurs among closely related sympatric dioecious fig taxa and that pollinators choose the floral volatiles of multiple fig taxa. The implications of pollinator sharing and inter-taxa gene flow on diversification, occurring even in this highly specialized obligate pollination system, require further study.
Collapse
Affiliation(s)
- Gang Wang
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, People's Republic of China Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, People's Republic of China
| | - Charles H Cannon
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, People's Republic of China Center for Tree Science, The Morton Arboretum, Lisle, IL 60532, USA
| | - Jin Chen
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, People's Republic of China
| |
Collapse
|
11
|
Yoder JB. Understanding the coevolutionary dynamics of mutualism with population genomics. AMERICAN JOURNAL OF BOTANY 2016; 103:1742-1752. [PMID: 27756732 DOI: 10.3732/ajb.1600154] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 09/06/2016] [Indexed: 06/06/2023]
Abstract
Decades of research on the evolution of mutualism has generated a wealth of possible ways whereby mutually beneficial interactions between species persist in spite of the apparent advantages to individuals that accept the benefits of mutualism without reciprocating - but identifying how any particular empirical system is stabilized against cheating remains challenging. Different hypothesized models of mutualism stability predict different forms of coevolutionary selection, and emerging high-throughput sequencing methods allow examination of the selective histories of mutualism genes and, thereby, the form of selection acting on those genes. Here, I review the evolutionary theory of mutualism stability and identify how differing models make contrasting predictions for the population genomic diversity and geographic differentiation of mutualism-related genes. As an example of the possibilities offered by genomic data, I analyze genes with roles in the symbiosis of Medicago truncatula and nitrogen-fixing rhizobial bacteria, the first classic mutualism in which extensive genomic resources have been developed for both partners. Medicago truncatula symbiosis genes, as a group, differ from the rest of the genome, but they vary in the form of selection indicated by their diversity and differentiation - some show signs of selection expected from roles in sanctioning noncooperative symbionts, while others show evidence of balancing selection expected from coevolution with symbiont signaling factors. I then assess the current state of development for similar resources in other mutualistic interactions and look ahead to identify ways in which modern sequencing technology can best inform our understanding of mutualists and mutualism.
Collapse
Affiliation(s)
- Jeremy B Yoder
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4 Canada
| |
Collapse
|
12
|
Hembry DH, Althoff DM. Diversification and coevolution in brood pollination mutualisms: Windows into the role of biotic interactions in generating biological diversity. AMERICAN JOURNAL OF BOTANY 2016; 103:1783-1792. [PMID: 27765775 PMCID: PMC6110533 DOI: 10.3732/ajb.1600056] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 05/10/2016] [Indexed: 05/05/2023]
Abstract
Brood pollination mutualisms-interactions in which specialized insects are both the pollinators (as adults) and seed predators (as larvae) of their host plants-have been influential study systems for coevolutionary biology. These mutualisms include those between figs and fig wasps, yuccas and yucca moths, leafflowers and leafflower moths, globeflowers and globeflower flies, Silene plants and Hadena and Perizoma moths, saxifrages and Greya moths, and senita cacti and senita moths. The high reciprocal diversity and species-specificity of some of these mutualisms have been cited as evidence that coevolution between plants and pollinators drives their mutual diversification. However, the mechanisms by which these mutualisms diversify have received less attention. In this paper, we review key hypotheses about how these mutualisms diversify and what role coevolution between plants and pollinators may play in this process. We find that most species-rich brood pollination mutualisms show significant phylogenetic congruence at high taxonomic scales, but there is limited evidence for the processes of both cospeciation and duplication, and there are no unambiguous examples known of strict-sense contemporaneous cospeciation. Allopatric speciation appears important across multiple systems, particularly in the insects. Host-shifts appear to be common, and widespread host-shifts by pollinators may displace other pollinator lineages. There is relatively little evidence for a "coevolution through cospeciation" model or that coevolution promotes speciation in these systems. Although we have made great progress in understanding the mechanisms by which brood pollination mutualisms diversify, many opportunities remain to use these intriguing symbioses to understand the role of biotic interactions in generating biological diversity.
Collapse
Affiliation(s)
- David H Hembry
- Department of Ecology and Evolutionary Biology, University of Arizona, P. O. Box 210088, Tucson, Arizona 85721 USA
| | - David M Althoff
- Department of Biology, Syracuse University, 107 College Place, Syracuse, New York, 13244 USA
| |
Collapse
|
13
|
Svensson GP, Raguso RA, Flatz R, Smith CI. Floral scent of Joshua trees (Yucca brevifolia sensu lato): Divergence in scent profiles between species but breakdown of signal integrity in a narrow hybrid zone. AMERICAN JOURNAL OF BOTANY 2016; 103:1793-1802. [PMID: 27578627 DOI: 10.3732/ajb.1600033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/13/2016] [Indexed: 05/14/2023]
Abstract
PREMISE OF THE STUDY The role of floral scent in facilitating reproductive isolation between closely related plants remains poorly understood. Yucca brevifolia and Yucca jaegeriana are pollinated by different moth species in allopatry, but in a narrow contact zone, pollinator-host specificity breaks down, resulting in hybridization between species. We explored the chemical basis for reproductive isolation and hybridization in these Joshua trees by characterizing the floral scent of each species in allopatry, analyzing scent profiles from trees in the contact zone, and matching these data with genotypic and phenotypic data. METHODS We analyzed floral volatiles using gas chromatography-mass spectrometry, tested for species divergence of scent profiles and classified trees in the contact zone as hybrid or either parental species. We used floral and vegetative morphological data and genotypic data to classify trees and analyzed whether certain trait combinations were more correlated than others with respect to assignment of trees and whether frequencies of classified tree types differed depending on which data set was used. KEY RESULTS The Joshua tree floral scent included oxygenated 8-carbon compounds not reported for other yuccas. The two species differed (P < 0.001) in scent profiles. In the contact zone, many hybrids were found, and phenotypic traits were generally weakly correlated, which may be explained by extensive gene flow between species or by exposure to different selection pressures. CONCLUSIONS Although the two Joshua tree species produce distinct floral scent profiles, it is insufficient to prevent attraction of associated pollinators to both hosts. Instead, floral morphology may be the key trait mediating gene flow between species.
Collapse
Affiliation(s)
- Glenn P Svensson
- Department of Biology, Lund University, Solvegatan 37, SE-22362 Lund Sweden
| | - Robert A Raguso
- Department of Neurobiology and Behavior, 215 Tower Road, Cornell University, Ithaca, New York 14853 USA
| | - Ramona Flatz
- Department of Biology, Willamette University, 900 State Street, Salem, Oregon 97301 USA
| | - Christopher I Smith
- Department of Biology, Willamette University, 900 State Street, Salem, Oregon 97301 USA
| |
Collapse
|
14
|
Suinyuy TN, Donaldson JS, Johnson SD. Geographical matching of volatile signals and pollinator olfactory responses in a cycad brood-site mutualism. Proc Biol Sci 2016; 282:20152053. [PMID: 26446814 DOI: 10.1098/rspb.2015.2053] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Brood-site mutualisms represent extreme levels of reciprocal specialization between plants and insect pollinators, raising questions about whether these mutualisms are mediated by volatile signals and whether these signals and insect responses to them covary geographically in a manner expected from coevolution. Cycads are an ancient plant lineage in which almost all extant species are pollinated through brood-site mutualisms with insects. We investigated whether volatile emissions and insect olfactory responses are matched across the distribution range of the African cycad Encephalartos villosus. This cycad species is pollinated by the same beetle species across its distribution, but cone volatile emissions are dominated by alkenes in northern populations, and by monoterpenes and a pyrazine compound in southern populations. In reciprocal choice experiments, insects chose the scent of cones from the local region over that of cones from the other region. Antennae of beetles from northern populations responded mainly to alkenes, while those of beetles from southern populations responded mainly to pyrazine. In bioassay experiments, beetles were most strongly attracted to alkenes in northern populations and to the pyrazine compound in southern populations. Geographical matching of cone volatiles and pollinator olfactory preference is consistent with coevolution in this specialized mutualism.
Collapse
Affiliation(s)
- Terence N Suinyuy
- School of Life Sciences, University of KwaZulu-Natal, P/Bag X01, Scottsville, Pietermaritzburg 3201, South Africa Kirstenbosch Research Centre, South African National Biodiversity Institute, P/Bag X7, Claremont, Cape Town 7735, South Africa Department of Biological Sciences, University of Cape Town, P/Bag Rondebosch, Cape Town 7701, South Africa
| | - John S Donaldson
- Kirstenbosch Research Centre, South African National Biodiversity Institute, P/Bag X7, Claremont, Cape Town 7735, South Africa Department of Biological Sciences, University of Cape Town, P/Bag Rondebosch, Cape Town 7701, South Africa Research Associate, Fairchild Tropical Botanic Garden, 10901 Old Cutler Road, Coral Gables, Miami, FL 33156, USA
| | - Steven D Johnson
- School of Life Sciences, University of KwaZulu-Natal, P/Bag X01, Scottsville, Pietermaritzburg 3201, South Africa
| |
Collapse
|
15
|
Kawakita A, Kato M. Revision of the Japanese species of Epicephala Meyrick with descriptions of seven new species (Lepidoptera, Gracillariidae). Zookeys 2016:87-118. [PMID: 27103875 PMCID: PMC4829671 DOI: 10.3897/zookeys.568.6721] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 01/14/2016] [Indexed: 11/17/2022] Open
Abstract
Epicephala moths are involved in obligate mutualisms with their Phyllanthaceae hosts, in which the female moths assure pollination and, in return, their progeny develop by consuming the seeds. Ecological, molecular and geographical data suggest that the genus includes several hundred species, but the majority remains to be formally described. Here we revise the Japanese species of Epicephala Meyrick, 1880. In addition to two previously named species, seven species are newly described: Epicephalaanthophiliasp. n., Epicephalalanceolatellasp. n., Epicephalaperplexasp. n., Epicephalaobovatellasp. n., Epicephalacorruptrixsp. n., Epicephalaparasiticasp. n. and Epicephalanudilinguasp. n. The first four are species involved in obligate pollination mutualism, while the fifth is a pollinating seed parasite and the last two are derived non-pollinating seed parasites of herbaceous Phyllanthus. Each of the nine Japanese Epicephela species is specialized to a single plant species in the genera Glochidion, Breynia or Phyllanthus, except for Epicephalaobovatella and Epicephalacorruptrix that each utilizes two closely related Glochidion species. Considerable variations are found in pollination and oviposition behaviors among species, which are reflected in their proboscis and ovipositor morphologies, respectively. Molecular phylogeny indicated that there have been repeated transitions in oviposition mode during the diversification of Epicephala, which were accompanied by changes in ovipositor morphology, as suggested by a correlation analysis. Keys to species are provided.
Collapse
Affiliation(s)
- Atsushi Kawakita
- Center for Ecological Research, Kyoto University, 2-509-3 Hirano, Otsu, Shiga 520-2113, Japan
| | - Makoto Kato
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyo 606-8501, Japan
| |
Collapse
|
16
|
Borges RM. On the Air: Broadcasting and Reception of Volatile Messages in Brood-Site Pollination Mutualisms. SIGNALING AND COMMUNICATION IN PLANTS 2016. [DOI: 10.1007/978-3-319-33498-1_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
17
|
Kawakita A, Mochizuki K, Kato M. Reversal of mutualism in a leafflower-leafflower moth association: the possible driving role of a third-party partner. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12633] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Atsushi Kawakita
- Center for Ecological Research; Kyoto University; 2-509-3 Hirano Otsu Shiga 520-2113 Japan
| | - Ko Mochizuki
- Center for Ecological Research; Kyoto University; 2-509-3 Hirano Otsu Shiga 520-2113 Japan
| | - Makoto Kato
- Graduate School of Human and Environmental Studies; Kyoto University; Yoshida-Nihonmatsu-cho Sakyo Kyoto 606-8501 Japan
| |
Collapse
|
18
|
Okamoto T, Okuyama Y, Goto R, Tokoro M, Kato M. Parallel chemical switches underlying pollinator isolation in Asian Mitella. J Evol Biol 2015; 28:590-600. [PMID: 25615872 PMCID: PMC4418413 DOI: 10.1111/jeb.12591] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 11/17/2014] [Accepted: 01/16/2015] [Indexed: 11/28/2022]
Abstract
Floral scents are among the key signals used by pollinators to navigate to specific flowers. Thus, evolutionary changes in scents should have strong impacts on plant diversification, although scent-mediated plant speciation through pollinator shifts has rarely been demonstrated, despite being likely. To examine whether and how scent-mediated plant speciation may have occurred, we investigated the Asimitellaria plant lineage using multidisciplinary approaches including pollinator observations, chemical analyses of the floral scents, electroantennographic analyses and behavioural bioassays with the pollinators. We also performed phylogenetically independent contrast analyses of the pollinator/floral scent associations. First, we confirmed that the pairs of the sympatric, cross-fertile Asimitellaria species in three study sites consistently attract different pollinators, namely long-tongued and short-tongued fungus gnats. We also found that a stereoisomeric set of floral volatiles, the lilac aldehydes, could be responsible for the pollinator specificity. This is because the compounds consistently elicited responses in the antennae of the long-tongued fungus gnats and had contrasting effects on the two pollinators, that is triggering the nectaring behaviour of long-tongued fungus gnats while repelling short-tongued fungus gnats in a laboratory experiment. Moreover, we discovered that volatile composition repeatedly switched in Asimitellaria between species adapted to long-tongued and short-tongued fungus gnats. Collectively, our results support the idea that recurrent scent-mediated speciation has taken place in the Asimitellaria–fungus gnat system.
Collapse
Affiliation(s)
- T Okamoto
- Graduate School of Human and Environmental Studies, Kyoto University, Sakyo, Kyoto, Japan; Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan
| | | | | | | | | |
Collapse
|
19
|
Interspecific and Intersexual Differences in the Chemical Composition of Floral Scent inGlochidionSpecies (Phyllanthaceae) in South China. J CHEM-NY 2015. [DOI: 10.1155/2015/865694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plants of theGlochidion(Phyllanthaceae) genus are pollinated exclusively by host-specificEpicephala(Gracillariidae) moths. Floral scent has been thought to play key role in the obligate pollination mutualism betweenGlochidionplants andEpicephalamoths, but few studies have been reported about chemical variation in floral volatiles ofGlochidionspecies in China. Floral volatiles of male and female flowers of fiveGlochidionspecies in south China were collected by dynamic headspace absorption technique and then were chemically analyzed by using gas chromatography-mass spectrometry. A total of 69 compounds were identified from floral scents of five investigated species.Glochidion hirsutumandG.zeylanicumshowed no qualitative differences in floral scent, whereas there were clear variations of floral scent among other species (G. eriocarpum,G.daltonii, andG. sphaerogynum) and also they distinctly differed from these two species. Male flowers emitted significantly more scent than female flowers.Glochidionplants exhibited qualitative and quantitative differences in floral scent between two sexes of flowers. The findings suggest that the volatile variation of floral scent amongGlochidionspecies reflects adaptations to specific pollinators. Sexual dimorphism in floral scent has evolved to signal alternative rewards provided by each sex toEpicephalamoths.
Collapse
|
20
|
Friberg M, Schwind C, Roark LC, Raguso RA, Thompson JN. Floral scent contributes to interaction specificity in coevolving plants and their insect pollinators. J Chem Ecol 2014; 40:955-65. [PMID: 25236381 DOI: 10.1007/s10886-014-0497-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/19/2014] [Accepted: 07/21/2014] [Indexed: 10/24/2022]
Abstract
Chemical defenses, repellents, and attractants are important shapers of species interactions. Chemical attractants could contribute to the divergence of coevolving plant-insect interactions, if pollinators are especially responsive to signals from the local plant species. We experimentally investigated patterns of daily floral scent production in three Lithophragma species (Saxifragaceae) that are geographically isolated and tested how scent divergence affects attraction of their major pollinator-the floral parasitic moth Greya politella (Prodoxidae). These moths oviposit through the corolla while simultaneously pollinating the flower with pollen adhering to the abdomen. The complex and species-specific floral scent profiles were emitted in higher amounts during the day, when these day-flying moths are active. There was minimal divergence found in petal color, which is another potential floral attractant. Female moths responded most strongly to scent from their local host species in olfactometer bioassays, and were more likely to oviposit in, and thereby pollinate, their local host species in no-choice trials. The results suggest that floral scent is an important attractant in this interaction. Local specialization in the pollinator response to a highly specific plant chemistry, thus, has the potential to contribute importantly to patterns of interaction specificity among coevolving plants and highly specialized pollinators.
Collapse
Affiliation(s)
- Magne Friberg
- Department of Ecology and Evolutionary Biology, University of California, 1156 High Street, Santa Cruz, CA, 95064, USA,
| | | | | | | | | |
Collapse
|
21
|
Song B, Chen G, Stöcklin J, Peng DL, Niu Y, Li ZM, Sun H. A new pollinating seed-consuming mutualism between Rheum nobile and a fly fungus gnat, Bradysia sp., involving pollinator attraction by a specific floral compound. THE NEW PHYTOLOGIST 2014; 203:1109-1118. [PMID: 24861151 DOI: 10.1111/nph.12856] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 04/17/2014] [Indexed: 06/03/2023]
Abstract
Pollinating seed-consuming mutualisms are regarded as exemplary models for studying coevolution, but they are extremely rare. In these systems, olfactory cues have been thought to play an important role in facilitating encounters between partners. We present a new pollinating seed-consuming mutualism from the high Himalayas between the endemic herb, Rheum nobile, and a fly fungus gnat, Bradysia sp. Seed production resulting from pollination by Bradysia flies and seed consumption by their larvae were measured to determine the outcome of this interaction. Floral scent analyses and behavioural tests were conducted to investigate the role of olfactory cues in pollinator attraction. Rheum nobile is self-compatible, but it depends mainly on Bradysia sp. females for pollination. Seed production resulting from pollination by adult flies is substantially higher than subsequent seed consumption by their larvae. Behavioural tests showed that an unusual floral compound, 2-methyl butyric acid methyl ester, emitted by plants only during anthesis, was attractive to female flies. Our results indicate that the R. nobile-Bradysia sp. interaction represents a new pollinating seed-consuming mutualism, and that a single unusual compound is the specific signal in the floral scent of R. nobile that plays a key role in attracting its pollinator.
Collapse
Affiliation(s)
- Bo Song
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Gao Chen
- Kunming Botanical Garden, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| | - Jürg Stöcklin
- Section of Plant Ecology, Institute of Botany, University of Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
| | - De-Li Peng
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Yang Niu
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| | - Zhi-Min Li
- School of Life Science, Yunnan Normal University, Kunming, 650500, China
| | - Hang Sun
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| |
Collapse
|
22
|
Wei ZD, Kobmoo N, Cruaud A, Kjellberg F. Genetic structure and hybridization in the species group of Ficus auriculata: can closely related sympatric Ficus species retain their genetic identity while sharing pollinators? Mol Ecol 2014; 23:3538-50. [PMID: 24938182 DOI: 10.1111/mec.12825] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 05/22/2014] [Accepted: 05/23/2014] [Indexed: 11/29/2022]
Abstract
Obligate mutualistic nursery pollination systems between insects and plants have led to substantial codiversification involving at least some parallel cladogenesis, as documented in Yucca, Ficus and Phyllanthaceae. In such systems, pollinators are generally species specific thus limiting hybridization and introgression among interfertile host species. Nevertheless, in the three systems, cases of one insect pollinating several plant species are reported. In most cases, host plants sharing pollinators are allopatric. However, in the case of the species group of Ficus auriculata, forms may co-occur over large parts of their range. We show here that the species group of F. auriculata is constituted by four well-defined genetic entities that share pollinators. We detected hybrids in nature mainly when both parental forms were growing nearby. Controlled crosses showed that F1 offspring could be successfully backcrossed. Hence, despite sharing pollinators and despite hybrid viability, the different forms have preserved their genetic and morphological identity. We propose that ecological differentiation among forms coupled with limited overlap of reproductive season has facilitated the maintenance of these interfertile forms. As such, establishment of pollinator host specificity may not be a prerequisite for sympatric diversification in Ficus.
Collapse
Affiliation(s)
- Z-D Wei
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China; Graduate School of the Chinese Academy of Sciences, Beijing, China
| | | | | | | |
Collapse
|
23
|
Okamoto T, Kawakita A, Goto R, Svensson GP, Kato M. Active pollination favours sexual dimorphism in floral scent. Proc Biol Sci 2014; 280:20132280. [PMID: 24266037 DOI: 10.1098/rspb.2013.2280] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Zoophilous flowers often transmit olfactory signals to attract pollinators. In plants with unisexual flowers, such signals are usually similar between the sexes because attraction of the same animal to both male and female flowers is essential for conspecific pollen transfer. Here, we present a remarkable example of sexual dimorphism in floral signal observed in reproductively highly specialized clades of the tribe Phyllantheae (Phyllanthaceae). These plants are pollinated by species-specific, seed-parasitic Epicephala moths (Gracillariidae) that actively collect pollen from male flowers and pollinate the female flowers in which they oviposit; by doing so, they ensure seeds for their offspring. We found that Epicephala-pollinated Phyllanthaceae plants consistently exhibit major qualitative differences in scent between male and female flowers, often involving compounds derived from different biosynthetic pathways. In a choice test, mated female Epicephala moths preferred the scent of male flowers over that of female flowers, suggesting that male floral scent elicits pollen-collecting behaviour. Epicephala pollination evolved multiple times in Phyllantheae, at least thrice accompanied by transition from sexual monomorphism to dimorphism in floral scent. This is the first example in which sexually dimorphic floral scent has evolved to signal an alternative reward provided by each sex, provoking the pollinator's legitimate altruistic behaviour.
Collapse
|
24
|
Filella I, Primante C, Llusià J, Martín González AM, Seco R, Farré-Armengol G, Rodrigo A, Bosch J, Peñuelas J. Floral advertisement scent in a changing plant-pollinators market. Sci Rep 2013; 3:3434. [PMID: 24305624 PMCID: PMC3852139 DOI: 10.1038/srep03434] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 11/18/2013] [Indexed: 11/18/2022] Open
Abstract
Plant-pollinator systems may be considered as biological markets in which pollinators choose between different flowers that advertise their nectar/pollen rewards. Although expected to play a major role in structuring plant-pollinator interactions, community-wide patterns of flower scent signals remain largely unexplored. Here we show for the first time that scent advertisement is higher in plant species that bloom early in the flowering period when pollinators are scarce relative to flowers than in species blooming later in the season when there is a surplus of pollinators relative to flowers. We also show that less abundant flowering species that may compete with dominant species for pollinator visitation early in the flowering period emit much higher proportions of the generalist attractant β-ocimene. Overall, we provide a first community-wide description of the key role of seasonal dynamics of plant-specific flower scent emissions, and reveal the coexistence of contrasting plant signaling strategies in a plant-pollinator market.
Collapse
Affiliation(s)
- Iolanda Filella
- 1] CSIC, Global Ecology Unit CREAF-CEAB-UAB, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain [2] CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Hembry DH, Kawakita A, Gurr NE, Schmaedick MA, Baldwin BG, Gillespie RG. Non-congruent colonizations and diversification in a coevolving pollination mutualism on oceanic islands. Proc Biol Sci 2013; 280:20130361. [PMID: 23760638 PMCID: PMC3652438 DOI: 10.1098/rspb.2013.0361] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 04/11/2013] [Indexed: 11/12/2022] Open
Abstract
A challenge for coevolutionary theory is how different types of interaction influence the diversification of coevolving clades. Reciprocal specialization is characteristic of certain coevolving, mutualistic interactions, but whether this specialization seen in ecological time constrains changes in patterns of interaction over evolutionary time remains unclear. Here, we examine the co-radiation of Glochidion trees (Phyllanthaceae: Phyllanthus s. l.) and pollinating, seed-predatory Epicephala moths (Lepidoptera: Gracillariidae) on young (mostly later than 5 Ma) oceanic islands in southeastern Polynesia. Epicephala are the sole known pollinators of Glochidion trees, and show extreme reciprocal specialization in continental Asia. We find that Glochidion and Epicephala diversified across these islands through repeated, non-congruent colonizations, and that one recently colonizing Epicephala lineage has spread across 12 host species in three archipelagos in less than 1 Myr. These results indicate that reciprocal specialization and coadaptation do not prevent dramatic changes in associations between intimately associated taxa over short evolutionary time scales. Not only are these host associations more dynamic than previously recognized, but these changes in patterns of interaction may play an important role in the diversification of coevolving taxa.
Collapse
Affiliation(s)
- David H Hembry
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, USA.
| | | | | | | | | | | |
Collapse
|
26
|
Friberg M, Schwind C, Raguso RA, Thompson JN. Extreme divergence in floral scent among woodland star species (Lithophragma spp.) pollinated by floral parasites. ANNALS OF BOTANY 2013; 111:539-550. [PMID: 23365407 PMCID: PMC3605946 DOI: 10.1093/aob/mct007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 12/11/2012] [Indexed: 05/31/2023]
Abstract
BACKGROUNDS AND AIMS A current challenge in coevolutionary biology is to understand how suites of traits vary as coevolving lineages diverge. Floral scent is often a complex, variable trait that attracts a suite of generalized pollinators, but may be highly specific in plants specialized on attracting coevolved pollinating floral parasites. In this study, floral scent variation was investigated in four species of woodland stars (Lithophragma spp.) that share the same major pollinator (the moth Greya politella, a floral parasite). Three specific hypotheses were tested: (1) sharing the same specific major pollinator favours conservation of floral scent among close relatives; (2) selection favours 'private channels' of rare compounds particularly aimed at the specialist pollinator; or (3) selection from rare, less-specialized co-pollinators mitigates the conservation of floral scent and occurrence of private channels. METHODS Dynamic headspace sampling and solid-phase microextraction were applied to greenhouse-grown plants from a common garden as well as to field samples from natural populations in a series of experiments aiming to disentangle the genetic and environmental basis of floral scent variation. KEY RESULTS Striking floral scent divergence was discovered among species. Only one of 69 compounds was shared among all four species. Scent variation was largely genetically based, because it was consistent across field and greenhouse treatments, and was not affected by visits from the pollinating floral parasite. CONCLUSIONS The strong divergence in floral scents among Lithophragma species contrasts with the pattern of conserved floral scent composition found in other plant genera involved in mutualisms with pollinating floral parasites. Unlike some of these other obligate pollination mutualisms, Lithophragma plants in some populations are occasionally visited by generalist pollinators from other insect taxa. This additional complexity may contribute to the diversification in floral scent found among the Lithophragma species pollinated by Greya moths.
Collapse
Affiliation(s)
- Magne Friberg
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA.
| | | | | | | |
Collapse
|
27
|
Wang G, Compton SG, Chen J. The mechanism of pollinator specificity between two sympatric fig varieties: a combination of olfactory signals and contact cues. ANNALS OF BOTANY 2013; 111. [PMID: 23179860 PMCID: PMC3555521 DOI: 10.1093/aob/mcs250] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS Pollinator specificity facilitates reproductive isolation among plants, and mechanisms that generate specificity influence species boundaries. Long-range volatile attractants, in combination with morphological co-adaptations, are generally regarded as being responsible for maintaining extreme host specificity among the fig wasps that pollinate fig trees, but increasing evidence for breakdowns in specificity is accumulating. The basis of host specificity was examined among two host-specific Ceratosolen fig wasps that pollinate two sympatric varieties of Ficus semicordata, together with the consequences for the plants when pollinators entered the alternative host variety. METHODS The compositions of floral scents from receptive figs of the two varieties and responses of their pollinators to these volatiles were compared. The behaviour of the wasps once on the surface of the figs was also recorded, together with the reproductive success of figs entered by the two Ceratosolen species. KEY RESULTS The receptive-phase floral scents of the two varieties had different chemical compositions, but only one Ceratosolen species displayed a preference between them in Y-tube trials. Specificity was reinforced at a later stage, once pollinators were walking on the figs, because both species preferred to enter figs of their normal hosts. Both pollinators could enter figs of both varieties and pollinate them, but figs with extra-varietal pollen were more likely to abort and contained fewer seeds. Hybrid seeds germinated at normal rates. CONCLUSIONS Contact cues on the surface of figs have been largely ignored in previous studies of fig wasp host preferences, but together with floral scents they maintain host specificity among the pollinators of sympatric F. semicordata varieties. When pollinators enter atypical hosts, post-zygotic factors reduce but do not prevent the production of hybrid offspring, suggesting there may be gene flow between these varieties.
Collapse
Affiliation(s)
- Gang Wang
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
- University of Chinese Academy of Science, Beijing 100039, China
| | - Stephen G. Compton
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK
| | - Jin Chen
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
- For correspondence. E-mail
| |
Collapse
|
28
|
Suinyuy TN, Donaldson JS, Johnson SD. Variation in the chemical composition of cone volatiles within the African cycad genus Encephalartos. PHYTOCHEMISTRY 2013; 85:82-91. [PMID: 23098901 DOI: 10.1016/j.phytochem.2012.09.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 09/21/2012] [Accepted: 09/26/2012] [Indexed: 06/01/2023]
Abstract
Volatiles play a key role in attraction of pollinators to cycad cones, but the extent to which volatile chemistry varies among cycad species is still poorly documented. Volatile composition of male and female cones of nineteen African cycad species (Encephalartos; Zamiaceae) was analysed using headspace technique and gas chromatography-mass spectrometry (GC-MS). A total of 152 compounds were identified among the species included in this study, the most common of which were monoterpenes, nitrogen-containing compounds and unsaturated hydrocarbons. Male and female cones emitted similar volatile compounds which varied in relative amounts with two unsaturated hydrocarbons (3E)-1,3-octadiene and (3E,5Z)-1,3,5-octatriene present in the volatile profile of most species. In a multivariate analysis of volatile profiles using non-metric multidimensional scaling (NMDS), a number of species clusters were identified according to shared emission of unsaturated hydrocarbons, pyrazines, benzenoids, aldehydes, alkanes and terpenoids. In comparison, terpenoids are common in Zamia and dominant in Macrozamia species (both in the family Zamiaceae) while benzenoids, esters, and alcohols are dominant in Cycas (Cycadaceae) and in Stangeria (Stangeriaceae). It is likely that volatile variation among Encephalartos species reflects both phylogeny and adaptations to specific beetle pollinators.
Collapse
Affiliation(s)
- Terence N Suinyuy
- Kirstenbosch Research Centre, South African National Biodiversity Institute, P/Bag X7, Claremont 7735, Cape Town, South Africa.
| | | | | |
Collapse
|
29
|
Diffuse coevolution between two Epicephala species (Gracillariidae) and two Breynia species (Phyllanthaceae). PLoS One 2012; 7:e41657. [PMID: 22848559 PMCID: PMC3407192 DOI: 10.1371/journal.pone.0041657] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 06/25/2012] [Indexed: 11/19/2022] Open
Abstract
The diffuse coevolution between two moth species (Epicephala lativalvaris and E. mirivalvata) and two plant species (Breynia fruticosa and B. rostrata) is reported based on field observations and indoor experiments conducted in Hainan and Fujian, China. Study results showed that the two Epicephala species jointly pollinated the two Breynia species, which led to a unique obligate pollination mutualism of two-to-two species specificity. A single Epicephala larva exclusively fed on seeds of host plants and developed to maturity by consuming all six seeds of each fruit, whereas a fraction of intact fruits were left to ensure the reproduction of plants within the whole population. Larvae of the two Epicephala species are competitive for resources; the population of E. mirivalvata is much smaller than that of E. lativalvaris, which has resulted from the differences in the female ovipositor structures and oviposition mode. The life history of Epicephala species highly coincides with the phenology of Breynia plants, and different phenology of B. fruticosa resulted in the different life history of the two Epicephala species in Hainan and Fujian. The natural hybridization of two host plants, possibly induced by the alternate pollination of two Epicephala species, is briefly discussed.
Collapse
|
30
|
Cornille A, Underhill JG, Cruaud A, Hossaert-McKey M, Johnson SD, Tolley KA, Kjellberg F, van Noort S, Proffit M. Floral volatiles, pollinator sharing and diversification in the fig-wasp mutualism: insights from Ficus natalensis, and its two wasp pollinators (South Africa). Proc Biol Sci 2012; 279:1731-9. [PMID: 22130605 PMCID: PMC3297447 DOI: 10.1098/rspb.2011.1972] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 11/08/2011] [Indexed: 11/12/2022] Open
Abstract
Combining biogeographic, ecological, morphological, molecular and chemical data, we document departure from strict specialization in the fig-pollinating wasp mutualism. We show that the pollinating wasps Elisabethiella stuckenbergi and Elisabethiella socotrensis form a species complex of five lineages in East and Southern Africa. Up to two morphologically distinct lineages were found to co-occur locally in the southern African region. Wasps belonging to a single lineage were frequently the main regional pollinators of several Ficus species. In South Africa, two sister lineages, E. stuckenbergi and E. socotrensis, pollinate Ficus natalensis but only E. stuckenbergi also regularly pollinates Ficus burkei. The two wasp species co-occur in individual trees of F. natalensis throughout KwaZulu-Natal. Floral volatile blends emitted by F. natalensis in KwaZulu-Natal were similar to those emitted by F. burkei and different from those produced by other African Ficus species. The fig odour similarity suggests evolutionary convergence to attract particular wasp species. The observed pattern may result from selection for pollinator sharing among Ficus species. Such a process, with one wasp species regionally pollinating several hosts, but several wasp species pollinating a given Ficus species across its geographical range could play an important role in the evolutionary dynamics of the Ficus-pollinating wasp association.
Collapse
Affiliation(s)
- A Cornille
- CEFE, Centre d'Ecologie Fonctionnelle et Evolutive-UMR 5175, 1919 Route de Mende, 34293 Montpellier, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
MOE ANNIKAM, ROSSI DANIELR, WEIBLEN GEORGED. Pollinator sharing in dioecious figs (Ficus: Moraceae). Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2011.01669.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
32
|
Svensson GP, Pellmyr O, Raguso RA. Pollinator attraction to volatiles from virgin and pollinated host flowers in a yucca/moth obligate mutualism. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.19258.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
33
|
Ibanez S, Dötterl S, Anstett MC, Baudino S, Caissard JC, Gallet C, Després L. The role of volatile organic compounds, morphology and pigments of globeflowers in the attraction of their specific pollinating flies. THE NEW PHYTOLOGIST 2010; 188:451-63. [PMID: 20553385 DOI: 10.1111/j.1469-8137.2010.03317.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
• Floral scents and visual cues of the globeflower Trollius europaeus may play a key role in the attraction of Chiastocheta flies, involved in a highly specific nursery pollination mutualism. • Here, headspace collection and GC-MS were used to identify and quantify the volatile organic compounds emitted by the globeflower. • Scents are produced in three different floral parts by four structures: secretory glands and flat epidermis cells in the abaxial sepal epidermis, conical cells in the adaxial sepal epidermis, and pollen. The blend is made up of 16 compounds commonly found in floral scents. Geographical variation among populations is low compared with variation amongst individuals within populations. Electroantenno-graphic analyses revealed that six compounds emitted by both anthers and sepals are detected by Chiastocheta flies. Removing the anthers hidden inside the globe from flowers in the field decreased the number of fly visits to globeflowers. • A multivariate analysis of the effect of several floral traits on pollinator visitation rate conducted in the field showed that both floral scents and visual flower cues play a role in pollinator attraction. However, their relative roles and the intensity of the selective pressures exerted on floral traits by pollinators appear to vary in time and space.
Collapse
Affiliation(s)
- Sébastien Ibanez
- Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, Grenoble, France
| | | | | | | | | | | | | |
Collapse
|
34
|
Svensson GP, Okamoto T, Kawakita A, Goto R, Kato M. Chemical ecology of obligate pollination mutualisms: testing the 'private channel' hypothesis in the Breynia-Epicephala association. THE NEW PHYTOLOGIST 2010; 186:995-1004. [PMID: 20345644 DOI: 10.1111/j.1469-8137.2010.03227.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
*Obligate mutualisms involving actively pollinating seed predators are among the most remarkable insect-plant relationships known, yet almost nothing is known about the chemistry of pollinator attraction in these systems. The extreme species specificity observed in these mutualisms may be maintained by specific chemical compounds through 'private channels'. Here, we tested this hypothesis using the monoecious Breynia vitis-idaea and its host-specific Epicephala pollinator as a model. *Headspace samples were collected from both male and female flowers of the host. Gas chromatography with electroantennographic detection (GC-EAD), coupled gas chromatography-mass spectrometry, and olfactometer bioassays were used to identify the floral compounds acting as the pollinator attractant. *Male and female flowers of B. vitis-idaea produced similar sets of general floral compounds, but in different ratios, and male flowers emitted significantly more scent than female flowers. A mixture of 2-phenylethyl alcohol and 2-phenylacetonitrile, the two most abundant compounds in male flowers, was as attractive to female moths as the male flower sample, although the individual compounds were slightly less attractive when tested separately. *Data on the floral scent signals mediating obligate mutualisms involving active pollination are still very limited. We show that system-specific chemistry is not necessary for efficient host location by exclusive pollinators in these tightly coevolved mutualisms.
Collapse
Affiliation(s)
- Glenn P Svensson
- Department of Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
| | - Tomoko Okamoto
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyo, Kyoto 606-8501, Japan
| | - Atsushi Kawakita
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyo, Kyoto 606-8501, Japan
| | - Ryutaro Goto
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyo, Kyoto 606-8501, Japan
| | - Makoto Kato
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyo, Kyoto 606-8501, Japan
| |
Collapse
|
35
|
Kawakita A, Okamoto T, Goto R, Kato M. Mutualism favours higher host specificity than does antagonism in plant-herbivore interaction. Proc Biol Sci 2010; 277:2765-74. [PMID: 20427340 DOI: 10.1098/rspb.2010.0355] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Coevolved mutualisms often exhibit high levels of partner specificity. Obligate pollination mutualisms, such as the fig-fig wasp and yucca-yucca moth systems, represent remarkable examples of such highly species-specific associations; however, the evolutionary processes underlying these patterns are poorly understood. The prevailing hypothesis suggests that the high degree of specificity in pollinating seed parasites is the fortuitous result of specialization in their ancestors because these insects are derived from endophytic herbivores that are themselves highly host-specific. Conversely, we show that in the Glochidion-Epicephala obligate pollination mutualism, pollinators are more host-specific than are closely related endophytic leaf-feeding taxa, which co-occur with Epicephala on the same Glochidion hosts. This difference is probably not because of shifts in larval diet (i.e. from leaf- to seed-feeding), because seed-eating lepidopterans other than Epicephala do not show the same degree of host specificity as Epicephala. Species of a tentative sister group of Epicephala each attack several distantly related plants, suggesting that the evolution of strict host specificity is tied to the evolution of pollinator habit. These results suggest that mutualists can attain higher host specificity than that of their parasitic ancestors and that coevolutionary selection can be a strong promoter of extreme reciprocal specialization in mutualisms.
Collapse
Affiliation(s)
- Atsushi Kawakita
- Graduate School of Human and Environmental Studies, Kyoto University, , Yoshida-Nihonmatsu-cho, Sakyo, Kyoto 606-8501, Japan.
| | | | | | | |
Collapse
|
36
|
Hossaert-McKey M, Soler C, Schatz B, Proffit M. Floral scents: their roles in nursery pollination mutualisms. CHEMOECOLOGY 2010. [DOI: 10.1007/s00049-010-0043-5] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
37
|
Anderson B, Alexandersson R, Johnson SD. Evolution and coexistence of pollination ecotypes in an African Gladiolus (Iridaceae). Evolution 2009; 64:960-72. [PMID: 19891625 DOI: 10.1111/j.1558-5646.2009.00880.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Pollinator-mediated selection has been suggested as a key driver of speciation in plants. We examined the potential role of hawkmoth pollinators in driving allopatric divergence and maintaining sympatric coexistence of morphotypes in the African iris Gladiolus longicollis. Floral tube length in this species varies from 35 mm to 130 mm across its geographic range and reflects the prevailing tongue lengths of local hawkmoth assemblages. The distribution of floral tube lengths is bimodal with two relatively discrete categories--long (about 90 mm) or short (about 50 mm)--that match the bimodal distribution of hawkmoth tongue lengths in eastern South Africa. At a contact site between these two floral morphs, we found few individuals of intermediate length, suggesting limited gene flow between morphs despite their interfertility. A difference in flowering phenology appears to be the main isolating barrier between morphs at this site. Long- and short-tubed morphs differed markedly in the chemical composition of their floral fragrance, a trait that could be used as a cue for morph-specific foraging by hawkmoths. Positive directional selection on tube length was found to occur in both morphs.
Collapse
Affiliation(s)
- Bruce Anderson
- School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X01 Scottsville, Pietermaritzburg, 3209, South Africa.
| | | | | |
Collapse
|
38
|
|
39
|
Cheng J, Shi J, Shangguan FZ, Dafni A, Deng ZH, Luo YB. The pollination of a self-incompatible, food-mimic orchid, Coelogyne fimbriata (Orchidaceae), by female Vespula wasps. ANNALS OF BOTANY 2009; 104:565-71. [PMID: 19218578 PMCID: PMC2720650 DOI: 10.1093/aob/mcp029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
BACKGROUND AND AIMS The study of specialized interactions between species is crucial to our understanding of processes in evolutionary ecology due to their profound effect on life cycles and diversification. Obligate pollination by a single wasp species is rare in Orchidaceae except in species with sexually deceptive flowers that are pollinated exclusively by male insects. The object of this study was to document pollination of the food-deceptive flowers of Coelogyne fimbriata, a species pollinated exclusively by female wasps. METHODS Field observations and experiments were conducted in two populations of C. fimbriata. Floral phenology was recorded, and functional floral architecture was measured. Insect visitors to flowers were observed from 2005 to 2007. Bioassay experiments were conducted to check whether the floral odour attracted pollinators. Natural (insect-mediated) rates of pollinarium removal, pollinium deposition on stigmas, and fruit set were recorded. To determine the importance of cross-pollination, the breeding system was assessed via controlled, hand-pollination experiments. KEY RESULTS Two populations of C. fimbriata with fragrant, nectarless flowers are pollinated by females of the same Vespula species (Vespidae, Hymenoptera). Experiments on wasps show that they crawl towards the source of the odour. The flowering period appears to coincide with an annual peak in Vespula colony expansion when additional workers forage for carbohydrates. Rates of pollinarium removal (0.069-0.918) and pollinium deposition on stigmas (0.025-0.695) are extremely variable. However, fruit set in C. fimbriata is always low (0.014-0.069) and appears to be based on self-incompatibility coupled with intraclonal (geitonogamous) deposition of pollinia. CONCLUSIONS Coelogyne fimbriata and Steveniella satyrioides are now the only orchid species known to have food-deceptive flowers that are pollinated exclusively by eusocial, worker wasps. In C. fimbriata, floral odour appears to be the major attractant. Sub-populations may go through flowering seasons when pollinators are abundant or infrequent, but fruit set always remains low because the obligate pollinator does not often appear to transfer pollinaria between intercompatible genets.
Collapse
Affiliation(s)
- Jin Cheng
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
- Graduate School, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jun Shi
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
- Graduate School, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Fa-Zhi Shangguan
- College of Biology, Guizhou University, Guiyang 500251, People's Republic of China
| | - Amots Dafni
- Laboratory of Pollination Ecology, Institute of Evolution, Haifa University, Haifa, Israel
| | - Zhen-Hai Deng
- Yachang Orchids Nature Reserve, Leye 533209, People's Republic of China
| | - Yi-Bo Luo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
- For correspondence. E-mail
| |
Collapse
|
40
|
Theis N, Kesler K, Adler LS. Leaf herbivory increases floral fragrance in male but not female Cucurbita pepo subsp. texana (Cucurbitaceae) flowers. AMERICAN JOURNAL OF BOTANY 2009; 96:897-903. [PMID: 21628242 DOI: 10.3732/ajb.0800300] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Mutualisms are key interactions that affect population dynamics and structure communities, but the extent to which mutualists can attract potential partners may depend on community context. Many studies have shown that leaf herbivory reduces pollinator visitation and have focused on reduced floral visual display and rewards as potential mechanisms. However, olfactory display plays a critical role in mediating interactions between plants, herbivores, and pollinators. We simulated leaf damage in Cucurbita pepo subsp. texana and measured fragrance emission and other floral characters of both male and female flowers. Contrary to our expectations, damage increased fragrance production, but only in male flowers. Female flowers, which were bigger and produced more fragrance than males, were unaffected by leaf damage. The greatest increase in floral fragrance compounds was in the terpenoids, which we hypothesize could be byproducts of defensively induced cucurbitacins, or they may function defensively themselves. In summary, this study is the first to demonstrate changes in floral fragrance due to leaf damage. Such changes in floral fragrance following herbivory may be a critical and overlooked mechanism mediating interactions between plants, herbivores, and pollinators.
Collapse
Affiliation(s)
- Nina Theis
- Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, Massachusetts 01003 USA
| | | | | |
Collapse
|