Distinct foraging tactics by pollinators have divergent consequences for the mating system of a tropical plant

Background/Question/Methods

It has long been recognized that pollinator foraging behaviour is an important factor influencing plant mating systems. However, studies on the ecology and evolution of plant mating systems have largely remained uncoupled from the dynamics and complexities of pollinator foraging behaviour. Therefore, resolving the consequences of functionally distinct pollinator foraging behaviours for plant mating systems is fundamental for understanding the ecological and evolutionary forces governing plant populations. In this study, we investigate the consequences of trapline foraging (a behaviour that involves repeated sequential visits to rewarding and replenishable resource locations) for the mating system of Heliconia tortuosa, a tropical forest herb. First, we performed parentage and sibship inference analysis to estimate outcrossing rates, multiple paternity, and near-neighbour mating. Second, capitalizing on these mating system parameters, we performed simulation modelling to quantify the impact of variation in trapline foraging tactics on multiple paternity and near-neighbour mating.

Results/Conclusions

Our analysis revealed high outcrossing rates, ubiquitous multiple paternity at the fruit and plant levels, and a pronounced departure from near-neighbour mating. Our simulation modelling revealed that variation in trapline foraging tactics influenced multiple paternity and near-neighbour mating. Collectively, our findings illustrate the consequences of trapline foraging for the mating system ofH. tortuosa. We argue that the trapline foraging pollinators of H. tortuosa elevate outcrossing rates, enhance multiple paternity at the fruit and plant levels, deposit pollen from a series of particular donors over the course of a flowering season, and limit near-neighbour mating. The particular trapline foraging tactics adopted by pollinators have divergent consequences for plant mating systems. This novel finding highlights the relevance of the dynamics and complexities of pollinator foraging behaviour as a driver of the ecology and evolution of plant mating systems.