Abstract

Plant compounds associated with herbivore defence occur widely in floral nectar and can impact pollinator health. We showed previously that Rhododendron ponticum nectar contains grayanotoxin I (GTX I) at concentrations that are lethal or sublethal to honeybees and a solitary bee in the plant's non-native range in Ireland. Here we further examined this conflict and tested the hypotheses that nectar GTX I is subject to negative pollinator-mediated selection in the non-native range, but that phenotypic linkage between GTX I levels in nectar and leaves acts as a constraint on independent evolution. We found that nectar GTX I experienced negative directional selection in the non-native range, in contrast to the native Iberian range, and that the magnitude and frequency of pollinator limitation indicated that selection was pollinator-mediated. Surprisingly, nectar GTX I levels were decoupled from those of leaves in the non-native range, which may have assisted post-invasion evolution of nectar without compromising the anti-herbivore function of GTX I (here demonstrated in bioassays with an ecologically relevant herbivore). Our study emphasizes the centrality of pollinator health as a concept linked to the invasion process, and how post-invasion evolution can be targeted toward minimizing lethal or sub-lethal effects on pollinators.This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.

Keywords

phenotypic selection; post-invasion evolution; toxic nectar; plant-herbivore-pollinator interactions

Published in

Philosophical Transactions B: Biological Sciences
2022, Volume: 377, number: 1853, article number: 20210168

SLU Authors

• Egan, Paul

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    

Associated SLU-program

Biodiversity
SLU Plant Protection Network


Sustainable Development Goals

SDG15 Life on land


UKÄ Subject classification

Ecology
Evolutionary Biology


Publication identifier

DOI: https://doi.org/10.1098/rstb.2021.0168

Permanent link to this page (URI)

https://res.slu.se/id/publ/120089