Animals often change their behaviour in the presence of other species and the environmental context they experience, and these changes can substantially modify the course their populations follow. In the case of animals involved in mutualistic interactions, it is still unclear how to incorporate the effects of these behavioural changes into population dynamics. We propose a framework for using pollinator functional responses to examine the roles of pollinator–pollinator interactions and abiotic conditions in altering the times between floral visits of a focal pollinator. We then apply this framework to a unique foraging experiment with different models that allow resource availability and sublethal exposure to a neonicotinoid pesticide to modify how pollinators forage alone and with co‐foragers. We found that all co‐foragers interfere with the focal pollinator under at least one set of abiotic conditions; for most species, interference was strongest at higher levels of resource availability and with pesticide exposure. Overall our results highlight that density‐dependent responses are often context‐dependent themselves.
Predicting the outcome of interactions between species is central to our current understanding of diversity maintenance. However, we have limited information about the robustness of many model-based predictions of species coexistence. This limitation is partly because several sources of uncertainty are often ignored when making predictions. Here, we introduce a framework to simultaneously explore how different mathematical models, different environmental contexts, and parameter uncertainty impact the probability of predicting species coexistence. Using a set of pairwise competition experiments on annual plants, we provide direct evidence that subtle differences between models lead to contrasting predictions of both coexistence and competitive exclusion. We also show that the effects of environmental context-dependency and parameter uncertainty on predictions of species coexistence are not independent of the model used to describe population dynamics. Our work suggests that predictions of species coexistence and extrapolations thereof may be particularly vulnerable to these underappreciated founts of uncertainty.
Pollinator foraging behavior determines floral visitation rates, an
important proxy to the strength of mutual- istic interactions. Although
there is evidence that pollinators modify their behavior in the presence
of other foragers, there are equivocal findings regarding whether or not
pollinators interfere with one another. We employ a functional-response
framework to analyse experimental data of times between floral visits
made by a focal pollinator and to estimate pollinator interference by
conspecifics and three other species. Additionally we develop and
compare models that allow different levels of resource availability and
the sub-lethal exposure to a neonicotinoid pesticide to modify how
pollinators forage alone and with co-foragers. We found that all
co-foragers interfere with a focal pollinator under at least one set of
abiotic conditions; for most species, interference was strongest at
higher levels of resource availability and with pesticide exposure.
Overall our results highlight that density-dependent responses are often
context dependent themselves.
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