Characteristics predicted to predispose mutualisms to phenological mismatches

Background/Question/Methods

Climate change is altering the timing of life history events in a wide array of species, many of which are involved in mutualistic interactions. Because many mutualisms hinge upon partner species locating each other in time, differential phenological shifts are likely to influence the strength, duration, and outcome of these interactions. At the extreme, climate change-driven shifts in phenology may result in phenological mismatch: the partial or complete loss of temporal overlap of mutualistic species. We have a growing understanding of how, when, and why phenological change can alter one type of mutualism – pollination. However, there has been a surprising lack of attention to other types of mutualism. We generate a set of predictions about the characteristics that may predispose mutualisms in general to phenological mismatches. The predictions involve features that are not unique to specific benefits, but that cut across traditional ways of grouping mutualisms. We illustrate these predictions with data from various systems, including a plant-pollinator network constructed around experimental manipulations of flowering phenology in a Wisconsin tallgrass prairie.

Results/Conclusions

Using first principles, we predict that the following characteristics of mutualism may increase the likelihood of phenological mismatch: (1) a non-symbiotic life history in which co-dispersal is absent; (2) brief, seasonal interactions; and (3) facultative, generalized interactions. Based on these predictions, we point to mutualisms that are more and less likely to be at risk of becoming phenologically mismatched. Focusing on interactions that vary in duration and specificity within the Wisconsin plant-pollinator network, we find that our predictions are generally met: plants with shorter flowering seasons and more-generalized visitor assemblages are more likely to lose interactions as their phenologies are experimentally shifted. These initial findings suggest ways in which other studies could be extended beyond system-specific details and illustrate the value of considering general characteristics that can predispose mutualisms to phenological disruption.