Prof. Mathilde DUFAŸ
CEFE (Centre d'Ecologie Fonctionnelle et Evolutive)
University of Montpellier
Evolution of floral traits mediated by pollinators
Co-Author: Isabelle DE CAUWER (EEP, Université de Lille)
Floral traits often function as an attractive signal to pollinators and can therefore impact plant reproductive success, through an effect on pollen receipt and/or export. In order to detect these effects of pollinator mediated-selection, and to distinguish it from other evolutionary forces, several methodologies can be used : (i) a description of traits variation (among individuals, among populations, if it applies, between sexual phenotypes), in order to hypothesize possible relationships between such variation in traits and some variation in selective pressures ; (ii) the study of floral traits effects on pollinator behaviour and (iii) selective gradient studies, which investigate correlations between traits and male and / or female individual reproductive success.
In this talk, I will present our research on two insect pollinated plant species that show contrasted life history traits (Silene dioica, a dioecious short-perennial with a generalist pollination system and Chamaerops humilis, a dioecious long perennial with an extremely specialized pollination system), and I will show how these different methodologies can be complementary for the study of floral traits evolution. We studied selective pressures mediated by pollinators on several traits (size and number of flowers, nectar, flowering phenology… in S. dioica ; quantity and composition of scents in C. humilis). Our aim was to understand how these selective pressures vary between male and female individuals, and whether they can vary among populations. Among other conclusions, we were able to verify that knowledge of the behavioural response of pollinators to floral traits alone does not always allow us to deduce the effects that these traits may have on the reproductive success of plants.
Prof. David Kleijn
Plant Ecology and Nature Conservation
Does managing for pollination produce benefits for pollinator conservation?
Co-Author: Jeroen SCHEPER (Plant Ecology and Nature Conservation Group, Wageningen University)
Seed and fruit set of many crops and most wild plants depends heavily on the diversity of wild pollinator communities that visit their flowers. Because wild pollinator communities are under threat, this has inspired many initiatives that aim to increase wild pollinator diversity, especially in agricultural landscapes. Such initiatives could represent win-wins for biodiversity and farmers. Here we explore under what conditions there are synergies between crop pollination and pollinator conservation. We analyse which species are providing most of the pollination benefits, what their population trends are and whether they benefit from measures on farmland. We furthermore examine whether pollinator enhancing measures are profitable for farmers when the costs of their establishment are taken into account. We conclude that although, across the board, beneficial effects of pollinator enhancing measures in farmland are modest and rarely promote crop yield or the species most in need of conservation, carefully designed measures have the potential to significantly boost pollination and wild pollinators. Uptake of such measures by farmers critically depends on society’s willingness to pay for their establishment, however, as they are rarely profitable.