Floral attractiveness and rewards affect the resilience of host-pollinator systems: A genetic model

Abstract

A genetic model was designed to depict what the resilience of host-pollinator interactions may be according to well known genetic rules and assuming an underlying genetic basis for (a) the attraction that flowers exert on pollinators, and (b) the fitness gain by the pollinator from visiting a flower. We explore the possible trajectories that a plant-pollinator system describes under certain bound conditions determined by a whole complex of attractiveness and reward scores. Such scores represent genetic relations between two diallelic loci assumed to control both traits. To see how the system would behave over time we created eight different scenarios, differing in the orientation they impose on the system. Half of these situations are of a reinforcing type (indicating a similar input both for attractiveness and rewards) and the remaining ones are conflicting (indicating opposite inputs). A numerical simulation was carried over seventy-five generations starting from Hardy-Weinberg equilibrium populations. We detected some general behavioral patterns in the final structure of frequencies. One of these may be viewed as a resilient type of structure (i.e., without memory of the initial population frequencies) which we hypothesize, may reflect the typical attraction-reward structure generally observed in nature. Another pattern is characterized by a pronounced lose of heterozygotes in the final structure, caused by the fixation of the most attractive phenotypes at the expense of the least attracting ones, independently of the pollinator genotype.