Evidence for a double mutualistic interaction between a lizard and a Mediterranean gymnosperm,Ephedra fragilis

An increasing number of double mutualisms (i.e. two interacting species benefiting each other in two different functions, e.g. pollination and seed dispersal) have been reported, mainly from island ecosystems, although we still lack much information on how effective such species are in both processes. Here, we assessed the pollination effectiveness of a double mutualism between an ancient Mediterranean gymnosperm, Ephedra fragilis, and a lizard, Podarcis lilfordi. On the one hand, we assessed the lizard contribution to different fitness measures (seed set and germination success), relative to that of insects and the wind effect; on the other, we determined the lizards’ seed removal rate (i.e. the quantity component of seed dispersal effectiveness). In both processes, we further tested for differences in their contributions among male, female and juvenile lizards. Ephedra fragilis showed to be mostly anemophilous, lizards and insects playing only a minor role on seed set. However, lizards qualitatively contributed to pollination success, as seeds coming from lizard-pollinated cones germinated at higher rates than those pollinated by wind or insects, although this was detected only for small seeds (
Our study provides evidence that the relationship between the Balearic endemic lizard Podarcis lilfordi and the plant Ephedra fragilis constitutes one of the five pollination/seed dispersal double mutualisms found around the World between an animal and a gymnosperm, besides representing the first double mutualism reported in the Mediterranean region. Although P. lilfordi does not contribute substantially to the pollination of E. fragilis, it does play a crucial role in the dispersal process. In turn, by means of the pollination drops and the fleshy cone scales, the plants feed its only seed disperser in this islet.