The relative contributions of insect and bird pollinators to outcrossing in an African <i>Protea</i> (Proteaceae)

Steenhuisen, Sandy–Lynn; Bank, Herman van der; Johnson, Steven D.

doi:10.3732/ajb.1100535

Cited by 18 publications

(10 citation statements)

References 71 publications

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“…We considered differences between treatment groups significant if 97.5% of the differences between randomly paired bootstrap estimates were greater or less than zero, following Steenhuisen et al . (). We used the same approach to determine whether estimates of biparental inbreeding differed significantly from zero.…”

Section: Methodsmentioning

confidence: 97%

“…Differences in mating system parameters between exclusion treatments were assessed through pairwise comparisons of bootstrap estimates, following Eckert & Barrett (1994). We considered differences between treatment groups significant if 97.5% of the differences between randomly paired bootstrap estimates were greater or less than zero, following Steenhuisen et al (2012). We used the same approach to determine whether estimates of biparental inbreeding differed significantly from zero.…”

Section: Estimation Of Mating Parametersmentioning

confidence: 99%

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Pollinator identity and spatial isolation influence multiple paternity in an annual plant

Rhodes

Fant²,

Skogen³

2017

Molecular Ecology

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The occurrence and extent of multiple paternity is an important component of variation in plant mating dynamics. However, links between pollinator activity and multiple paternity are generally lacking, especially for plant species that attract functionally diverse floral visitors. In this study, we separated the influence of two functionally distinct floral visitors (hawkmoths and solitary bees) and characterized their impacts on multiple paternity in a self-incompatible, annual forb, Oenothera harringtonii (Onagraceae). We also situated pollinator-mediated effects in a spatial context by linking variation in multiple paternity to variation in plant spatial isolation. We documented pronounced differences in the number of paternal sires as function of pollinator identity: on average, the primary pollinator (hawkmoths) facilitated mating with nearly twice as many pollen donors relative to the secondary pollinator (solitary bees). This effect was consistent for both isolated and nonisolated individuals, but spatial isolation imposed pronounced reductions on multiple paternity regardless of pollinator identity. Considering that pollinator abundance and pollen dispersal distance did not vary significantly with pollinator identity, we attribute variation in realized mating dynamics primarily to differences in pollinator morphology and behaviour as opposed to pollinator abundance or mating incompatibility arising from underlying spatial genetic structure. Our findings demonstrate that functionally distinct pollinators can have strongly divergent effects on polyandry in plants and further suggest that both pollinator identity and spatial heterogeneity have important roles in plant mating dynamics.

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Section: Methodsmentioning

confidence: 97%

Section: Estimation Of Mating Parametersmentioning

confidence: 99%

Pollinator identity and spatial isolation influence multiple paternity in an annual plant

Rhodes

Fant²,

Skogen³

2017

Molecular Ecology

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“…In some cases, birds were more effective in their quality effectiveness (e.g., Robertson et al 2005;Fumero-Cabán and Meléndez-Ackerman 2007), while in others in their quantity (Waser and Price 1990;Vaughton 1992;Mayfield et al 2001). Birds appear to be more effective than ectothermic pollinators (e.g., insects, lizards) when these are scarce (Steenhuisen et al 2012), in high-elevation habitats (Cruden 1972) or in early flowering periods, when temperatures are usually low and limit the activity of ectotherms (Waser and Price 1990;Vaughton 1992;Valido et al 2002). Thus, this pattern of greater variation in QNC than in QLC is expected for those pollinator assemblages, such as our study system, with marked inter-specific differences in life modes.…”

Section: The Pe Landscapementioning

confidence: 97%

Quantity and quality components of effectiveness in insular pollinator assemblages

2013

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Ecologically isolated habitats (e.g., oceanic islands) favor the appearance of small assemblages of pollinators, generally characterized by highly contrasted life modes (e.g., birds, lizards), and opportunistic nectar-feeding behavior. Different life modes should promote a low functional equivalence among pollinators, while opportunistic nectar feeding would lead to reduced and unpredictable pollination effectiveness (PE) compared to more specialized nectarivores. Dissecting the quantity (QNC) and quality (QLC) components of PE, we studied the opportunistic bird-lizard pollinator assemblage of Isoplexis canariensis from the Canary Islands to experimentally evaluate these potential characteristics. Birds and lizards showed different positions in the PE landscape, highlighting their low functional equivalence. Birds were more efficient than lizards due to higher visitation frequency (QNC). Adult lizards differed from juveniles in effecting a higher production of viable seeds (QLC). The disparate life modes of birds and lizards resulted in ample intra- and inter-specific PE variance. The main sources of PE variance were visitation frequency (both lizards and birds), number of flowers probed (lizards) and proportion of viable seeds resulting from a single visit (birds). The non-coincident locations of birds and lizards on the PE landscape indicate potential constraints for effectiveness. Variations in pollinator abundance can result in major effectiveness shifts only if QLC is relatively high, while changes in QLC would increase PE substantially only at high QNC. The low functional equivalence of impoverished, highly contrasted pollinator assemblages may be an early diagnostic signal for pollinator extinction potentially driving the collapse of mutualistic services.

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“…Apparently, the genotypic diversity was high enough to prevent broad scale intra‐clonal pollination. Alternatively, when the homozygotes are viable but exhibit reduced fitness due to inbreeding depression, their contribution at the population level may be minimal (Hämmerli and Reusch , Steenhuisen et al ).…”

Section: Discussionmentioning

confidence: 99%

The effect of herbivores on genotypic diversity in a clonal aquatic plant

Hidding¹,

Meirmans

Klaassen³

et al. 2014

Oikos

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In clonal plants, vegetative parts may outcompete seeds in the absence of disturbance, limiting the build-up of genotypic diversity through repeated seedling recruitment (RSR). Herbivory may provide disturbance and trigger establishment of strong colonizers (seeds) at the expense of strong competitors (clonal propagules). In the clonal aquatic fennel pondweed Potamogeton pectinatus , two distinct herbivore guilds may modify the dynamics of propagation. In winter, Bewick's swans may deplete patches of tubers, promoting seedling establishment in spring. In summer, seed consumption by waterfowl can reduce the density of viable seeds but grazing may also reduce tuber production and hence facilitate seedling establishment. Th is study is among the fi rst to experimentally test herbivore impact on plant genotypic diversity. We assess the separate and combined eff ects of both herbivore guilds on genotypic diversity and structure of fennel pondweed beds. Using microsatellites, we genotyped P. pectinatus from an exclosure experiment and assessed the contribution of herbivory, dispersal and sexual reproduction to the population genetic structure. Despite the predominance of clonal propagation in P. pectinatus , we found considerable genotypic diversity. Within the experimental blocks, kinship among genets decreased with geographic distance, clearly identifying a role for RSR in the maintenance of genotypic diversity within the fennel pondweed beds. However, over a period of fi ve years, none of the herbivory treatments aff ected genotypic diversity. Hence, sexual reproduction on a local scale is important in this putatively clonal plant and possibly suffi cient to ensure a relatively high genotypic diversity even in the absence of herbivores. Although we cannot preclude a role of herbivory in shaping genotypic diversity of a clonal plant, after fi ve years of exclusion of the two investigated herbivore guilds no measurable eff ect on genotypic diversity was detected.

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The relative contributions of insect and bird pollinators to outcrossing in an African Protea (Proteaceae)

Abstract: Since outcrossing rates were not reduced when birds were excluded, we infer that insects are effective agents of cross pollination in P. caffra. This helps to explain the evolution of traits associated with insect pollination, such as fruity floral scent, in this species.

Cited by 18 publications

References 71 publications

Pollinator identity and spatial isolation influence multiple paternity in an annual plant

Pollinator identity and spatial isolation influence multiple paternity in an annual plant

Quantity and quality components of effectiveness in insular pollinator assemblages

The effect of herbivores on genotypic diversity in a clonal aquatic plant

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