Breakage of mutualisms by exotic species: the case of Cneorum tricoccon L. in the Balearic Islands (Western Mediterranean Sea)

In this study we tested the hypothesis that the dispersal success (estimated here as fruit removal rate) of a native shrub species living in the Balearic Archipelago, Cneorum tricoccon L. (Cneoraceae), has decreased significantly in those islands where endemic lizards of the genus Podarcis have disappeared. These lizards acted as the main seed dispersers of the plant and became extinct after the introduction of carnivores. At least one of these carnivores, the pine marten (Martes martes L.), is also an important frugivore, consuming the fruits and dispersing the seeds of C. tricoccon and thus allowing the comparison of fruit removal rates between the two groups of vertebrates (lizards and mammals). We further tested the possibility that lizards (in particular, P. pityusensis Bosca` ) could be exerting selection on seed size.


Núria Riera, Anna Traveset and Oscar García (2002) Journal of Biogeography, 29