Figure 1. Importance of different pollination processes for
plant pollination success as a function of floral abundance, as
determined by the mathematical model. Comparison of pollination success
expected for low, medium and high values of A) pollinator abundance, B)
pollinator specialization, C) pollen removal and D) carryover at
variable floral abundance (see Table 1 for parameter values). E)
Importance of the quantity component of pollination, represented by
pollinator abundance, and the quality component, determined by
pollinator specialization and carryover as a function of floral
abundance (measured as the average between the importance of pollinator
specialization and carryover). F) Hypothetical representation of the
pollination systems offering the highest pollination success at
different floral abundance. Specialization on pollinators with high
pollen carryover and level of specialization is favoured at low floral
abundance (hypothetical examples; hawkmoths and hummingbirds). At
intermediate abundance, specialized pollination by more abundant
pollinators (hypothetical example; bees) is favoured. At high floral
abundance, most pollinators are not sufficiently abundant to remove most
pollen grains and generalization becomes more advantageous. When floral
abundance is too high for the pollinator community to remove most pollen
grains, reliance on abiotic pollen vectors is expected.
Figure 2. Plant-pollinator networks resulting from simulated
communities of different plant species and pollinator attributes. A, B)
Plant-pollinator networks formed with plant species of variable floral
abundance result in variable levels of generalization among plant
species. C, D) Networks composed entirely of low-abundance plant species
result in high level of specialization. E, F) Networks composed entirely
of high-abundance plant species result in widespread generalization. G,
H) Networks composed of low-abundance plant species that interact with a
pollinator community composed of functionally similar pollinators result
in specialization and niche partitioning among plant species for the use
of the different pollinators. In A, C, E and G, the thickness of the
links represents the number of visits of a pollinator to a plant
species. In B, D, F and H, grey squares denote interaction between a
plant and a pollinator and darker shades represent higher frequencies of
interaction.
Figure 3. Degree of generalization and attributes of the
pollinators on which a plant species colonizing simulated plant
communities evolved as a function of its floral abundance. The parameter
values represent the average values of pollen carryover capacity,
specialization and abundance of the pollinators on which the new
colonist evolved and degree of floral generalization of the new
colonist. The parameter values on the y-axis were normalized so that the
minimum value corresponds to 0 and the maximum value corresponding to 1.
The standard error of the mean parameter values among the 100
simulations is presented as the shaded area around the mean values.