Pollination strategies in the face of pollinator decline
Résumé
The recent pollinator decline in developed countries has been documented in many parts of the world and its anthropogenic causes are now identified. Because pollinators contribute to the sexual reproduction of many plant species, pollinator decline constitutes a potential threat on insect-pollinated plant populations. Moreover, it is susceptible to impede pollination services to crops in agriculture. In this paper, I review the empirical evidence that pollinator decline translates (or not) into pollen limitation for plants and alters plant-pollinator networks. I also analyse the possibility of short-term evolution of plant pollination strategies. In particular, I discuss how changes in pollinator fauna constitutes new selection pressures for plants and how plant reproductive traits are able to respond rapidly to such new selection regime. Mating system evolutionary theory thus predicts that short-term evolution may allow plant populations to adapt to pollinator decline, potentially rescuing populations, as predicted by the evolutionary rescue theory. Nevertheless, mating system theory and empirical data support the idea that evolutionary rescue through mating system adaptation is not always possible. Finally, I discuss how plant evolution may disturb plant-pollinator interactions potentially breaking major trophic links in ecosystems, which could in turn reinforce pollinator's extinction in the future.
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