The angiosperms show remarkable floral diversity. However, the
ecological processes involved in flower diversification remain poorly
understood. In this article I propose that different species' floral
abundances drive adaptation to different pollinators and promote
different degrees of specialization. In this view, interspecific
variability in abundance can foster floral diversification. I develop a
mathematical model of pollen transfer considering the interaction of
several pollination processes---pollen removal and carryover, intra- and
interspecific competition for pollinator visitation, and interspecific
pollen transfer---that are linked to floral abundance. To assess if and
how floral abundance can generate floral diversity, I use the model to
assemble plant-pollinator networks from simulated plant and pollinator
communities. The model shows that evolution on highly specialized
pollinators and pollinators with high pollen carryover capacity is
favoured at low floral abundance, while evolution on more abundant
pollinators is favoured at high floral abundance. Furthermore, floral
specialization is favoured at low floral abundance, while generalization
is favoured at high abundance. In simulated plant communities of
variable floral abundance, different pollinator systems evolve among the
different plant species. The model demonstrates a new mechanism by which
floral diversity can be generated, contributing to our understanding of
floral evolution and diversification.