Consequences of species extinctions in complex food webs
Final Report Abstract
This project addressed the consequences of extinctions in complex food webs. In these networks of species linked by their feeding interactions, the loss of a species can have direct consequences for its consumers and its resources. For instance, the most pronounced effect would be if a consumer looses its only resource, which would inevitably lead to its secondary extinctions. These effects can cascade through the networks and ultimately affect all other co-existing species to different extents. While conservation biologists have studied the population dynamics and extinction risks of a variety of different species, they have not addressed generalities in extinction risks. This project used models of complex food webs to unravel characteristics of species that go primary extinct that have the highest chance of unleashing avalanches of secondary extinctions and also detect community properties that indicate high sensitivity to these extinction waves. Specifically, the project documented high risk profiles following primary extinctions of basal producers in the food web (mainly plants that provide the energy input into the communities) and large-bodied top predators. Additionally, communities that are most sensitive to secondary extinction waves possess characteristic distributions of abundances across population-averaged body masses. Subsequent projects addressed the consequences of warming and nutrient enrichment as two of the major drivers of global change. Interestingly, the results suggest that these two major threats of natural biodiversity may counteract and thus diminish each others consequences for natural ecosystems. While warming may thus ameliorate the negative effects of nutrient enrichment, it also comes at the cost of a consumer starvation risk, which may also undermine natural biodiversity. Together, the studies of this project have thus provided general risk profiles for extinction risks and also unraveled more specific consequences of the anthropogenic stressors warming and nutrient enrichment.
Publications
- (2011): Robustness to secondary extinctions: Comparing trait-based sequential deletions in static and dynamic food webs. Basic and Applied Ecology 12(7): 571-580
Curtsdotter, A., Binzer, A., Brose, U., de Castro, F., Ebenman, B., Eklöf, A., Riede, J.O., Thierry, A., Rall, B.C.
(See online at https://dx.doi.org/10.1016/j.baae.2011.09.008) - (2011): Size-based food web characteristics govern the response to species extinctions. Basic and Applied Ecology 12(7): 581-589
Riede, J.O., Binzer, A., Brose, U., de Castro, F. , Curtsdotter, A., Rall, B.C., Eklöf, A.
(See online at https://doi.org/10.1016/j.baae.2011.09.006) - (2011): The susceptibility of species to extinctions in model communities. Basic and Applied Ecology 12(7): 590-599
Binzer, A., Brose, U., Curtsdotter, A., Eklöf, A., Rall, B.C., Riede, J.O., de Castro, F.
(See online at https://doi.org/10.1016/j.baae.2011.09.002) - (2012): The dynamics of food chains under climate change and nutrient enrichment. Philosophical Transactions of the Royal Society B, 367(1605):2935-2944
Binzer, A., Guill, C., Brose, U. & Rall, B.C.
(See online at https://doi.org/10.1098/rstb.2012.0230)
