Plant generalization on pollinators: Species property or local phenomenon?

Despite recent increased interest in the frequency and evolutionary consequences of generalization in plant-pollinalor systems, little is known on whether plant generalization oil pollinators actually is a species-level trait. This paper address, the following questions. for the insect-pollinated shrub Lavandula latifolia: (1) Are different populations of this pollinatolr-generalist plant similarly generalized? (2) Within a highly generalized population, are all plants similarly pollinator-generalists? Comparable values for richness in pollinator species were obtained from individual- or population-specific rarefaction curves as the projected number of distinct pollinator species implicated in 100 flower visits (S-RAR100). Simple counts of pollinator species recorded per individual or population (S-OBS) were weakly or nonsignificantly correlated with corresponding S-RAR100 figures and closely correlated with flower visitation frequency. The pollination system of L. latifolia was highly generalized at the regional level, but populations differed greatly in pollinator species richness (S-RAR100). Within the population intensively studied, individual plants had quite variable degrees of generalization, comparable in magnitude to variation among populations. It is concluded that generalization was not an invariant, species-level property in L. latifolia. Furthermore, pollinator diversity estimates based on S-OBS data may be heavily contingent on aspects related to both research design (sampling effort) and biological phenomena (variation in pollinator abundance or visitation rates), which may either mask or distort underlying ecological patterns of interest.