“…10,12 In some extreme cases, both parties could co-evolve morphologically and behaviourally to allow only one-on-one plant-pollinator interactions, whereby the plant protects access to rewards for its specific pollinator -a feature of, amongst others, many genera in the Orchidaceae. 13 It has been argued that the formation of specific floral structures in plants is largely driven by means of natural selection from their respective pollinators. 9 Better pollinator-flower compatibility would, therefore, result in higher selection, through increased fertilisation events of these individuals.…”
Section: Evolution Of Plant-pollinator Interactionsmentioning
Plant-pollinator interactions are essential for maintaining both pollinator and plant communities in native and agricultural environments. Animal-instigated pollination can be complex. Plants are usually visited by a number of different animal species, which in turn may visit flowers of several plant species. Therefore, the identification of the pollen carried by flower visitors is an essential first step in pollination biology. The skill and time required to identify pollen based on structure and morphology has been a major stumbling block in this field. Advances in the genetic analysis of DNA, using DNA barcoding, extracted directly from pollen offers an innovative alternative to traditional methods of pollen identification. This technique, which is reviewed in detail, can be used on pollen loads sampled from bees in the field and from specimens in historic collections. Here the importance of pollination, the role-players involved, their management and the evolution of their interactions, behaviour and morphology are reviewed -with a special focus on South African bees.
Significance:• Pollen metabarcoding will enable the identification of pollen for a multitude of uses, including agriculture, conservation and forensics.• Plant-pollinator interaction documentation through pollen identification gives a more certain record of a visitor being a pollinator rather than a flower visitor that could be a nectar gatherer.
“…10,12 In some extreme cases, both parties could co-evolve morphologically and behaviourally to allow only one-on-one plant-pollinator interactions, whereby the plant protects access to rewards for its specific pollinator -a feature of, amongst others, many genera in the Orchidaceae. 13 It has been argued that the formation of specific floral structures in plants is largely driven by means of natural selection from their respective pollinators. 9 Better pollinator-flower compatibility would, therefore, result in higher selection, through increased fertilisation events of these individuals.…”
Section: Evolution Of Plant-pollinator Interactionsmentioning
Plant-pollinator interactions are essential for maintaining both pollinator and plant communities in native and agricultural environments. Animal-instigated pollination can be complex. Plants are usually visited by a number of different animal species, which in turn may visit flowers of several plant species. Therefore, the identification of the pollen carried by flower visitors is an essential first step in pollination biology. The skill and time required to identify pollen based on structure and morphology has been a major stumbling block in this field. Advances in the genetic analysis of DNA, using DNA barcoding, extracted directly from pollen offers an innovative alternative to traditional methods of pollen identification. This technique, which is reviewed in detail, can be used on pollen loads sampled from bees in the field and from specimens in historic collections. Here the importance of pollination, the role-players involved, their management and the evolution of their interactions, behaviour and morphology are reviewed -with a special focus on South African bees.
Significance:• Pollen metabarcoding will enable the identification of pollen for a multitude of uses, including agriculture, conservation and forensics.• Plant-pollinator interaction documentation through pollen identification gives a more certain record of a visitor being a pollinator rather than a flower visitor that could be a nectar gatherer.
“…Male bees subsequently expose perfume compounds during courtship to convey information on male quality (fitness) or identity (species) ( Eltz et al , 2003 ). While gathering floral volatiles from orchids, male bees inadvertently remove pollinaria and upon visitation of another flower deposit pollinaria on the stigmatic surface ( Allen, 1954 ; Dressler, 1981 ; Rodriguez Flores et al , 1995 ; Hetherington-Rauth and Ramírez, 2015 ). Thus, reliable floral cues (scents) are needed to ensure species-specific pollination.…”
Section: Introductionmentioning
confidence: 99%
“…Because Gongora orchids lack additional floral rewards (such as nectar and/or edible pollen) that could potentially attract other pollinators, they rely exclusively on male euglossine bees for sexual reproduction. Between one and five species of eulgossine bee visit a single species of Gongora in a given locality ( Dressler, 1968 a ; Whitten, 1985 ; Hentrich, 2004 ; Hetherington-Rauth and Ramírez, 2015 ). Fig .…”
Section: Introductionmentioning
confidence: 99%
“…(B) Male euglossine bees collect perfume compounds and store them in hind-leg pockets (arrow) subsequently to expose to females during courtship display (photo: B. Jacobi). (C) Putative phylogenetic relationships of Gongora lineages sampled in the present study (as summarized by Hetherington-Rauth and Ramírez, 2015 ). …”
Section: Introductionmentioning
confidence: 99%
“…10–20 flowers (but some produce up to 50 flowers) that open simultaneously and smell strongest in the morning hours when male bees are most active ( Fig. 1A, B ) ( Hetherington-Rauth and Ramírez, 2015 ). Flowers typically last a few days before wilting.…”
•Background and Aims Animal-pollinated angiosperms have evolved a variety of signalling mechanisms to attract pollinators. Floral scent is a key component of pollinator attraction, and its chemistry modulates both pollinator behaviour and the formation of plant–pollinator networks. The neotropical orchid genus Gongora exhibits specialized pollinator associations with male orchid bees (Euglossini). Male bees visit orchid flowers to collect volatile chemical compounds that they store in hind-leg pouches to use subsequently during courtship display. Hence, Gongora floral scent compounds simultaneously serve as signalling molecules and pollinator rewards. Furthermore, because floral scent acts as the predominant reproductive isolating barrier among lineages, it has been hypothesized that chemical traits are highly species specific. A comparative analysis of intra- and inter-specific variation of floral scent chemistry was conducted to investigate the evolutionary patterns across the genus.•Methods Gas chromatography–mass spectrometry (GC-MS) was used to analyse the floral scent of 78 individuals belonging to 28 different species of Gongora from two of the three major lineages sampled across the neotropical region. Multidimensional scaling and indicator value analyses were implemented to investigate the patterns of chemical diversity within and among taxonomic groups at various geographic scales. Additionally, pollinator observations were conducted on a sympatric community of Gongora orchids exhibiting distinct floral scent phenotypes.•Key Results A total of 83 floral volatiles, mainly terpenes and aromatic compounds, were detected. Many of the identified compounds are common across diverse angiosperm families (e.g. cineole, eugenol, β-ocimene, β-pinene and terpinen-4-ol), while others are relatively rare outside euglossine bee-pollinated orchid lineages. Additionally, 29 volatiles were identified that are known to attract and elicit collection behaviour in male bees. Floral scent traits were less variable within species than between species, and the analysis revealed exceptional levels of cryptic diversity. Gongora species were divided into 15 fragrance groups based on shared compounds. Fragrance groups indicate that floral scent variation is not predicted by taxonomic rank or biogeographic region.•Conclusions
Gongora orchids emit a diverse array of scent molecules that are largely species specific, and closely related taxa exhibit qualitatively and quantitatively divergent chemical profiles. It is shown that within a community, Gongora scent chemotypes are correlated with near non-overlapping bee pollinator assemblies. The results lend support to the hypothesis that floral scent traits regulate the architecture of bee pollinator associations. Thus, Gongora provides unique opportunities to examine the interplay between floral traits and pollinator specialization in plant–pollinator mutualisms.
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