Pollination ecology provides some new insight into evolution and systematics of Mediterranean legumes

Plant evolution and diversification is driven by several environmental selective pressures and constraints. Pollinators’ ethology, form, and size play a relevant role in determining floral characters, and more so when pollination is specialized (i.e. due to one or very few insect species). Floral characters, in turn, constitute the main ground of traditional classification system. Recent molecular phylogenies of Mediterranean Legumes have challenged the commonly accepted systematics, as several genera usually regarded as “natural” ones proved to be polyphyletic. The question arises, whether the incongruence between natural groups based on floral traits and monophyla based on molecular homology is due to experimental flaws, or whether it has a biological background. The authors present recent evidence that pollination in Mediterranean Legumes is much more specialized than previously reported. Even species pollinated or visited by several insect species are specialized, in that their fitness is enhanced only by one or few of them, while other visitors and pollinators may exert little influence on seed production, or even depress it. Such specialization may account for homoplasy of floral characteristics, so that several “natural” genera may reflect common pollination syndromes rather than represent monophyletic clades.