Abstrakt
Pollinators often tend to visit the same flower type as the last one visited, even if more rewarding flower types are available. This behaviour is called flower constancy and was hypothesized to promote evolution towards specialization of pollination systems.
Flower constancy nontrivially interacts with pollinator preference for different plant species, which has not yet been fully recognized. In the present study, we examine the independent relative influences of pollinator's preference and flower constancy on plant's gain from pollination.
We formulate and analyse a general Markov transition matrix model of pollinator visitation and parameterize it with field data from a system of three plant and two pollinator species. Flower constancy generally had weaker effects on plant's gain than pollinator preferences.
The adaptiveness of manipulating flower constancy for plants depends on which mechanism underlying flower constancy is assumed to be the dominant one in a given system. Interestingly, large areas of preference-constancy parameter space did not exhibit any biologically relevant selection pressure on increasing pollinator preference or flower constancy, that is selection towards specialization of pollination system.
This suggests that generalized pollination systems may be maintained even in the absence of substantial temporal and spatial variation in plant pollinator spectra.