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.

Keywords

phenotypic selection; post-invasion evolution; toxic nectar; plant–herbivore–pollinatorinteractions

Published in

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

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

Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss


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