The chemical ecology of plant-pollinator interactions: recent advances and future directions

Parachnowitsch, Amy L.; Manson, Jessamyn S.

doi:10.1016/j.cois.2015.02.005

Cited by 34 publications

(27 citation statements)

References 53 publications

(27 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The relative importance of selection on pollen chemistry via pollinator attraction vs. plant defense will depend on the magnitude of pollen limitation of plant reproduction as well as levels of pollen herbivory and their effect on plant fitness. We cannot yet rule out the possibility that pollen alkaloids, or lack thereof, may reflect pleiotropic effects of the production and transport of alkaloids across other tissues (Adler, ), selection via pollen's role as a gamete, or to reduce over‐collection by pollen‐harvesting bees (Parachnowitsch and Manson, ). However, the low concentration of alkaloids that we observed in the pollen of these three Lupinus species is consistent with the hypothesis that these species may experience selection against the use of alkaloids to defend their pollen from nonpollinating pollen consumers.…”

Section: Discussionmentioning

confidence: 99%

“…Consistent with this hypothesis, in some plants that offer nectar as a reward, the concentrations of secondary compounds in pollen far exceed those in nectar and may be comparable to those found in vegetative tissues (Palmer‐Young et al., ). However, approximately 20,000 nectarless plant species offer pollen as the sole reward to pollinators (Willmer, ), and little is known about the pollen secondary chemistry in these pollen rewarding species or about the variation in pollen chemistry among pollen‐rewarding species (Parachnowitsch and Manson, ). Hereafter, we refer to plants that produce no nectar and only offer pollen as a reward to pollinators as pollen‐rewarding plants.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Pollen and vegetative secondary chemistry of three pollen‐rewarding lupines

Heiling

Cook

Lee

et al. 2019

American J of Botany

View full text Add to dashboard Cite

Premise Optimal defense theory predicts that selection should drive plants to disproportionally allocate resources for herbivore defense to tissues with high fitness values. Because pollen's primary role is the transport of gametes, plants may be expected to defend it from herbivory. However, for many animal‐pollinated plants, pollen serves a secondary role as a pollinator reward. These dual roles may present a conflict between selection to defend pollen from herbivores and selection to reward pollinators. Here, we investigate whether pollen secondary chemistry in three pollen‐rewarding Lupinus species better reflects the need to defend pollen or reward pollinators. Methods Lupinus (Fabaceae) species are nectarless, pollen‐rewarding, and produce defensive quinolizidine and/or piperidine alkaloids throughout their tissues. We used gas chromatography to identify and quantitate the alkaloids in four aboveground tissues (pollen, flower, leaf, stem) of three western North American lupines, L. argenteus, L. bakeri, and L. sulphureus, and compared alkaloid concentrations and composition among tissues within individuals. Results In L. argenteus and L. sulphureus, pollen alkaloid concentrations were 11–35% of those found in other tissues. We detected no alkaloids in L. bakeri pollen, though they were present in other tissues. Alkaloid concentrations were not strongly correlated among tissues within individuals. We detected fewer alkaloids in pollen compared to other tissues, and pollen contained no unique alkaloids. Conclusions Our results are consistent with the hypothesis that, in these pollen‐rewarding species, pollen secondary chemistry may reflect the need to attract and reward pollinators more than the need to defend pollen from herbivory.

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Pollen and vegetative secondary chemistry of three pollen‐rewarding lupines

Heiling

Cook

Lee

et al. 2019

American J of Botany

View full text Add to dashboard Cite

show abstract

“…The role of pollen secondary metabolites in the ecology and evolution of pollinators remains virtually unexplored (Parachnowitsch & Manson, 2015). However, many observations suggest that pollen composition could affect the evolution of bees.…”

Section: Impacts Of Pollen Defence On Bee Ecology and Evolutionmentioning

confidence: 99%

“…Consequently, pollen defence compounds have strong potential to affect plant-pollinator interactions. Yet, perhaps because of the dual role of pollen and the relative difficulty of manipulating its composition, most research concerning defence compounds in floral rewards has focused on nectar (Irwin et al, 2014;Parachnowitsch & Manson, 2015;Stevenson et al, 2017; but see Muth et al, 2016 for a study of bee responses to a deterrent compound added to pollen). Furthermore, it has historically been assumed that pollen chemistry plays a trivial role in plant-pollinator interactions (Wcislo & Cane, 1996;Larkin et al, 2008;Willmer, 2011).…”

Section: Introductionmentioning

confidence: 99%

Defence compounds in pollen: why do they occur and how do they affect the ecology and evolution of bees?

Rivest

Forrest

2019

New Phytologist

View full text Add to dashboard Cite

Pollen plays two important roles in angiosperm reproduction, serving as a vehicle for the plant's male gametes, but also, in many species, as a lure for pollen-feeding animals. Despite being an important food source for many pollinators, pollen often contains compounds with known deterrent or toxic properties, as documented in a growing number of studies. Here we review these studies and discuss the role of pollen defensive compounds in the coevolutionary relationship between plants and bees, the preeminent consumers of pollen. Next, we evaluate three hypotheses that may explain the existence of defensive compounds in pollen. The pleiotropy hypothesis, which proposes that defensive compounds in pollen merely reflect physiological spillover from other plant tissues, is contradicted by evidence from several species. Although plants may experience selection to defend pollen against poor-quality pollinators, we also find only partial support for the protectionagainst-pollen-collection-hypothesis. Finally, pollen defences might protect pollen from colonisation by antagonistic microorganisms (antimicrobial hypothesis), although data to evaluate this idea are scarce. Further research on the effects of pollen defensive compounds on pollinators, pollen thieves, and pollen-colonising microbes will be needed to understand why many plants have chemically defended pollen, and the consequences of those defences for pollen consumers.

show abstract

“…When toxic or deterrent compounds are found in nectar, they tend to appear at considerably lower concentrations than in other plant parts (see Parachnowitsch & Manson (2015) and references therein). Their presence may indicate a defensive function against invertebrate and microbial antagonists such as floral larcenists and nectar-dwelling pathogens (Gonzalez-Teuber & Heil 2009;McArt et al 2014;Aizenberg-Gershtein et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Plant toxin levels in nectar vary spatially across native and introduced populations

et al. 2016

View full text Add to dashboard Cite

Summary Secondary compounds in nectar can function as toxic chemical defences against floral antagonists, but may also mediate plant–pollinator interactions. Despite their ecological importance, few studies have investigated patterns of spatial variation in toxic nectar compounds in plant species, and none outside their native range. Grayanotoxin I (GTX I) occurs in nectar of invasive Rhododendron ponticum where it is toxic to honeybees and some solitary bee species. We examined (i) geographic variation in the composition of nectar GTX I, as well as GTX III (which is not toxic to these species), in the native and introduced range of R. ponticum, (ii) how their expression is structured at patch and landscape scales within ranges, and (iii) whether climatic and environmental factors underpin spatial patterns. While both GTXs varied within ranges, variation in GTX I, but not GTX III, was detected between ranges. GTX I expression was thus markedly lower or (in 18% of cases) absent from nectar in introduced plants. Spatial autocorrelation was apparent at both patch and landscape scales and in part related to heat load interception by plants (a function of latitude, aspect and slope). As expression of nectar GTXs was generally robust to environmental variation, and aggregated in space, this trait has the potential to be spatially discriminated by consumers. Given the specificity of change to GTX I, and its differential toxicity to some bee species, we conclude that its expression was likely to have been influenced during invasion by interaction with herbivores/consumers, either via pollinator‐mediated selection or enemy release from floral antagonists. Synthesis. As the first demonstration of large‐scale geographic variation and spatial structure in toxic nectar compounds, this work deepens our understanding of the chemical ecology of floral interactions in native and introduced species. Spatially explicit studies of nectar secondary compounds are thus required to show how the extent and structure of spatial variation may affect floral ecology. Future development of invasion theory should incorporate a holistic view of plant defence, beyond antagonistic interactions, which integrates the consequences of chemically defended mutualist rewards.

show abstract

The chemical ecology of plant-pollinator interactions: recent advances and future directions

Cited by 34 publications

References 53 publications

Pollen and vegetative secondary chemistry of three pollen‐rewarding lupines

Pollen and vegetative secondary chemistry of three pollen‐rewarding lupines

Defence compounds in pollen: why do they occur and how do they affect the ecology and evolution of bees?

Plant toxin levels in nectar vary spatially across native and introduced populations

Contact Info

Product

Resources

About