Trends in Plant Science
SpotlightSpecial Issue: Systems BiologyTipping points in ecological networks
Section snippets
Pollinator declines: impacts and insights from network research
Pollination is crucial for the reproduction of most flowering plants, and animal-pollinated crops are making up an increasing proportion of global food production [1]. However, plant-pollinator interactions are threatened by multiple environmental changes, with effects that vary across species, regions, and drivers [2]. This variability has hindered generalisations across species, and led in part to a search for common patterns in the complex mutualistic interactions occurring among diverse
Critical transitions
Community collapses may occur when environmental conditions change significantly enough that even a minor increase in the perturbation is enough to generate a self-propagating shift into a contrasting state of dynamic behaviour, for example, a series of extinctions leading to the collapse of the whole community. Such ‘phase shifts’ typically occur in complex systems that have more than one stable state, and a critical transition defines the bifurcation at which populations either persist or go
Tipping points in ecological networks
To study how network structure influences the resilience of communities to critical transitions, Lever et al. [8] simulated pollination networks within a range of controlled values of connectedness and nestedness, and created a dynamic population model with a parameter representing a driver of pollination decline. By gradually modulating the value of this parameter, the populations were driven through an increasingly stressful environment until every population went extinct. The authors then
The way forward
The exciting findings of Lever et al. [8] raise several interesting research questions, such as how changing the necessary assumptions of their model would affect the results. For example, their driver of pollinator decline affected all species equally, whereas environmental changes generate both winners and losers [2]. Also, this parameter entailed a gradual change of a single stressor (i.e., a ‘press’ perturbation), which is only one out of a range of possible environmental change scenarios.
Acknowledgements
J.M.T. and C.C. are funded by a Rutherford Discovery Fellowship to J.M.T., administered by the Royal Society of New Zealand. This paper is a contribution to Imperial College's Grand Challenges in Ecosystems and the Environment initiative.
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