Resolving the consequences of pollinator foraging behaviour for plant mating systems is a fundamental challenge in evolutionary ecology. Pollinators may adopt particular foraging tactics: complete trapline foraging (repeated movements along a fixed route), sample-and-shift trapline foraging (a variable route that incorporates information from previous experiences), and territorial foraging (stochastic movements within a restricted area). Studies that integrate these pollinator foraging tactics with plant mating systems are generally lacking.

We investigate the consequences of particular pollinator foraging tactics for Heliconia tortuosa. We combine parentage and sibship inference analysis with simulation modeling to: (1) estimate mating system parameters; (2) infer the foraging tactic adopted by the pollinators; and (3) quantify the impact of pollinator foraging tactics on mating system parameters.

We found high outcrossing rates, ubiquitous multiple paternity, and a pronounced departure from near-neighbour mating. We also found that plants repeatedly receive pollen from a series of particular donors. We infer that the pollinators primarily adopt complete trapline foraging and occasionally engage in sample-and-shift trapline foraging. This enhances multiple paternity without a substantial increase in near-neighbour mating.

The particular pollinator foraging tactics have divergent consequences for multiple paternity and near-neighbour mating. Thus, pollinator foraging behaviour is an important driver of the ecology and evolution of plant mating systems.

We performed parentage and sibship inference analysis using COLONY2 V2.0.6.6. Parentage assignments were used to estimate the rate of self-pollination, near-neighbour mating (proportion of seeds sired by a maternal plant from the same sampling location) and non-near-neighbour mating (proportion of seeds sired by a maternal or unsampled plant from beyond the sampling location). Excluding seeds classified as self-pollination and the seed with an ambiguous parentage assignment, we estimated correlated paternity in a hierarchical fashion: within maternal plants, within fruits, and among fruits from the same bract.

We performed pattern-oriented simulation modeling to infer the particular foraging tactic adopted by the pollinators of H. tortuosa. We defined and assessed four parameters of pollinator foraging that represented: (1) the probability that a seed was sired by the last-visited plant (p); (2) the frequency at which pollinators engage in sample-and-shift trapline foraging (PSST), relative to complete trapline foraging; (3) the amount of pollen removed, on average, from a flower when pollinators ‘sample’ a particular plant during sample-and-shift trapline foraging (PRMV), relative to complete trapline foraging; and (4) the ideal number of near-neighbour plants involved in sample-and-shift trapline foraging (NNBR). We used a broad range of values for each parameter of pollinator foraging to simulate the pollen load received by individual flowers of different near-neighbour plants (NNBR) over the course of a flowering season. Based on the simulated pollen loads received by different near-neighbour plants (NNBR), we quantified correlated paternity and near-neighbour mating expected to result from each combination of parameters of pollinator foraging. We used pattern-oriented simulation modeling to infer the specific combination of parameters of pollinator foraging that best fit the observed estimates of correlated paternity and near-neighbour mating derived from the parentage and sibship inference analysis. To quantify the impact of variation in pollinator foraging tactics on plant mating systems more broadly, we performed a sensitivity analysis that included a full-factorial design based on a broad range of values for each parameter of pollinator foraging.

COLONY2 V2.0.6.6

COANCESTRY V1.0.1.9 

R 4.1.0