The current paradigm in plant-pollinator biology largely stems from Stebbins’ (1970) “most effective pollinator principle”, which postulates that (i) floral characteristics are shaped by the most frequent and efficient pollinators, and (ii) character syndromes must be interpreted based on the attraction of the most efficient pollinator by the stimulus elicited by such traits.
The convergence of floral traits towards “floral syndromes”, putatively adapted to the morphology, sensory system and nutritional physiology of certain pollinators, seems however at odds with the widespread generality of plant-pollinator systems, in which most flowers are visited by many different pollinators. The “most-efficient pollinator” principle seems also at odds with the existence of complex floral traits that do not seem to favor the most efficient pollinator – such as the red color of ornitophylous flowers (despite the fact that birds do not perceive this color better than others) or the long corollas/spurs and pending habit of some hummingbird- and moth-pollinated flowers (which force pollinators to spend considerable amounts of energy hovering and inserting long prosbosces).
In close co-operation with the group of Miguel A. Rodriguez-Gironés (EEZA, CSIC, in Almería), we are exploring an alternative process that may complement or replace the most efficient pollinator principle: the evolution of floral barriers, i.e. traits that conceal or difficult the access to floral rewards, such as pollen or nectar. We are developing modeling and empirical work addressing the ecological mechanisms that underlay this hypothesis and its evolutionary consequences, and its potential implications for the topology of plant-pollinator networks. A central point in our work is the analysis of pollinator foraging strategies and its interaction with the spatial arrangement of flowers and floral traits, both within and among populations. These include optimal pollinators, but also less efficient ones that, in the presence of the former, may behave as pollen or nectar larcenists - as in the case of Lonicera implexa, in which hummingbird hawkmoths compete with nectar-robbing bumblebees for the reward of the long-corolla flowers.
Since recently, we are also exploring the effects of floral-ambush predators on pollinator visitation and its consequences for the evolution of floral traits. We are exploring whether floral-ambush predators may have evolutionary effects comparable to those of floral barriers, using two systems from Spain, Australia and the easter tropics: crab spiders and weaver ants.
The convergence of floral traits towards “floral syndromes”, putatively adapted to the morphology, sensory system and nutritional physiology of certain pollinators, seems however at odds with the widespread generality of plant-pollinator systems, in which most flowers are visited by many different pollinators. The “most-efficient pollinator” principle seems also at odds with the existence of complex floral traits that do not seem to favor the most efficient pollinator – such as the red color of ornitophylous flowers (despite the fact that birds do not perceive this color better than others) or the long corollas/spurs and pending habit of some hummingbird- and moth-pollinated flowers (which force pollinators to spend considerable amounts of energy hovering and inserting long prosbosces).
In close co-operation with the group of Miguel A. Rodriguez-Gironés (EEZA, CSIC, in Almería), we are exploring an alternative process that may complement or replace the most efficient pollinator principle: the evolution of floral barriers, i.e. traits that conceal or difficult the access to floral rewards, such as pollen or nectar. We are developing modeling and empirical work addressing the ecological mechanisms that underlay this hypothesis and its evolutionary consequences, and its potential implications for the topology of plant-pollinator networks. A central point in our work is the analysis of pollinator foraging strategies and its interaction with the spatial arrangement of flowers and floral traits, both within and among populations. These include optimal pollinators, but also less efficient ones that, in the presence of the former, may behave as pollen or nectar larcenists - as in the case of Lonicera implexa, in which hummingbird hawkmoths compete with nectar-robbing bumblebees for the reward of the long-corolla flowers.
