DO MUTUALISMS MATTER - ASSESSING THE IMPACT OF POLLINATOR AND DISPERSER DISRUPTION ON PLANT EXTINCTION

There is a voluminous literature on pollination and dispersal, very li ttle of which deals with the consequences of reproductive failure and its most extreme consequence: extinction. The risk of plant extinction s can be assessed by considering the probability of dispersal or polli nator failure, reproductive dependence on the mutualism and demographi c dependence on seeds. Traits for ranking species rapidly according to these three criteria are indicated. Analysis of case studies suggests that plants often compensate for high risk in one of the three catego ries by low risk in another. For example, self-incompatible plants wit h rare specialist pollinators often propagate vegetatively. Some syste ms, including elements of the Cape flora and lowland tropical rain for est, lack compensatory traits and the risk of plant extinction from fa iles mutualism is high.