The biology of alkaline nectar in the purple toothwort (Lathraea clandestina): ground level defences

Prŷs-Jones, Oliver E.; Willmer, Pat

doi:10.1111/j.1095-8312.1992.tb00650.x

Cited by 22 publications

(22 citation statements)

References 14 publications

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“…Therefore, given the contrasting effects of bacteria and yeasts on sucrose (figure 3c), glucose (figure 3d) and fructose (figure 3e), changes in sugar composition may underlie the microbial effects we observed on pollination. In addition, some birds are known to avoid highly acidic solutions [41,42], although little work has been done on hummingbirds specifically. Thus, the precipitous pH reduction by Gluconobacter-a species that has been used in vinegar production since prehistoric times [43]-may also have been responsible for the bacterial effects on pollination.…”

Section: (A) Possible Mechanismsmentioning

confidence: 99%

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

2013

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Mutualistic interactions are often subject to exploitation by species that are not directly involved in the mutualism. Understanding which organisms act as such 'third-party' species and how they do so is a major challenge in the current study of mutualistic interactions. Here, we show that even species that appear ecologically similar can have contrasting effects as third-party species. We experimentally compared the effects of nectar-inhabiting bacteria and yeasts on the strength of a mutualism between a hummingbird-pollinated shrub, Mimulus aurantiacus, and its pollinators. We found that the common bacterium Gluconobacter sp., but not the common yeast Metschnikowia reukaufii, reduced pollination success, seed set and nectar consumption by pollinators, thereby weakening the plant-pollinator mutualism. We also found that the bacteria reduced nectar pH and total sugar concentration more greatly than the yeasts did and that the bacteria decreased glucose concentration and increased fructose concentration whereas the yeasts affected neither. These distinct changes to nectar chemistry may underlie the microbes' contrasting effects on the mutualism. Our results suggest that it is necessary to understand the determinants of microbial species composition in nectar and their differential modification of floral rewards to explain the mutual benefits that plants and pollinators gain from each other.

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Section: (A) Possible Mechanismsmentioning

confidence: 99%

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

2013

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“…Fortunately, some studies have also established a link between nectar chemistry and toxicity (Table 3). In some cases, secondary compounds were isolated from nectar known to have toxic or repellent qualities, but the compounds were not tested separately (Pryce-Jones 1942, Kozlova 1957, Barragan de Dominguez 1973, Prys-Jones and Willmer 1992. Frankie et al (1982) correlated decreased pollinator visitation with increased phenolics in nectar, but with a sample size of only three trees.…”

Section: Toxic Nectar: Its Nature and Occurrencementioning

confidence: 99%

The ecological significance of toxic nectar

Adler¹

2000

Oikos

519

509

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Although plant‐herbivore and plant‐pollinator interactions have traditionally been studied separately, many traits are simultaneously under selection by both herbivores and pollinators. For example, secondary compounds commonly associated with herbivore defense have been found in the nectar of many plant species, and many plants produce nectar that is toxic or repellent to some floral visitors. Although secondary compounds in nectar and toxic nectar are geographically and phylogenetically widespread, their ecological significance is poorly understood. Several hypotheses have been proposed for the possible functions of toxic nectar, including encouraging specialist pollinators, deterring nectar robbers, preventing microbial degradation of nectar, and altering pollinator behavior. All of these hypotheses rest on the assumption that the benefits of toxic nectar must outweigh possible costs; however, to date no study has demonstrated that toxic nectar provides fitness benefits for any plant. Therefore, in addition to these adaptive hypotheses, we should also consider the hypothesis that toxic nectar provides no benefits or is tolerably detrimental to plants, and occurs due to previous selection pressures or pleiotropic constraints. For example, secondary compounds may be transported into nectar as a consequence of their presence in phloem, rather than due to direct selection for toxic nectar. Experimental approaches are necessary to understand the role of toxic nectar in plant‐animal interactions.

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“…Diverse adaptations have been proposed by which plants could deter exploitation by ants (e.g. Prys‐Jones & Willmer 1992).…”

Section: Who Exploits Mutualisms?mentioning

confidence: 99%

The exploitation of mutualisms

2001

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Mutualisms (interspecific cooperative interactions) are ubiquitously exploited by organisms that obtain the benefits mutualists offer, while delivering no benefits in return. The natural history of these exploiters is well‐described, but relatively little effort has yet been devoted to analysing their ecological or evolutionary significance for mutualism. Exploitation is not a unitary phenomenon, but a set of loosely related phenomena: exploiters may follow mixed strategies or pure strategies at either the species or individual level, may or may not be derived from mutualists, and may or may not inflict significant costs on mutualisms. The evolutionary implications of these different forms of exploitation, especially the threats they pose to the stability of mutualism, have as yet been minimally explored. Studies of this issue are usually framed in terms of a “temptation to defect” that generates a destabilizing conflict of interest between partners. I argue that this idea is in fact rather inappropriate for interpreting most observed forms of exploitation in mutualisms. I suggest several alternative and testable ideas for how mutualism can persist in the face of exploitation.

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The biology of alkaline nectar in the purple toothwort (Lathraea clandestina): ground level defences

Cited by 22 publications

References 14 publications

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

The ecological significance of toxic nectar

The exploitation of mutualisms

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