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Erin Jo Tiedeken (PhD student)

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PhD project: Ecological effects of toxic nectar and pollen: A comparison of impacts on floral visitors in invasive & native ranges.

Floral nectar is generally accepted to function as a pollinator reward, thus the frequent presence of toxic secondary compounds in nectar and pollen seems illogical.  Several hypotheses have been proposed to explain how this paradoxical phenomenon may have evolved; (Adler 2000)however, the role of toxic nectar and pollen in the ecology of biological invasions has yet to be investigated. The aim of this study is to compare the ecological effects of toxic nectar and pollen in native and invasive habitats and to determine if these toxins promote, prevent, or do not play a significant role in invasion.  Rhododendron ponticum (Ericaceae) was introduced into Britain in 1763 and to Ireland in the late 18th century and has since become extensively naturalised in these areas. Itsnectar and pollen contain grayanotoxins, grayene diterpenoids, which act as sodium channel activators in cell membranes.  Molecular analysis of chloroplast and ribosomal DNA indicate that the populations in the British Isles originate from Iberian ancestors.  We will study R. ponticum in its invaded (Irish and British) and native (Spanish and Portuguese) populations and use it as a model system to infer information about the impact of toxic nectar on invasion success on an international scale.  We will conduct focal observations and transect walks in order to assess the floral communities at each site, as well as carry out lab bioassays to determine how R. ponticum nectar and pollen affect mutualist and antagonist flower-visitor fitness and survival.  The effect of grayanotoxins on intestinal parasites of key pollinators is also being investigated. This project brings together international, interdisciplinary researchers to study how toxins in nectar and pollen influence successful invasion by alien plants and how they influence pollinator communities.

Funded by IRCSET & the National Science Foundation (GRFP)


Contact details

Botany Building, School of Natural Sciences, Trinity College Dublin, Dublin 2. Tel: +353-1-8962208 Email:


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Last updated 13 October 2014