Towards a framework for predicting arctic food web response to global climate change
Final Report Abstract
Predator-prey interactions are a key biological interaction and crucial in structuring animal communities such as of the highly diverse and abundant group of arthropods (i.e. insects and their allies). Which factors are shaping these interactions and how they respond to ongoing changes of the environment, is however largely unknown. Identifying these factors provides important insights on elementary ecological processes and predict the future of arthropod communities affected by global climate change. In my DFG research fellowship in the group of Prof Tomas Roslin at the University of Helsinki, I tackled these very questions by analyzing predator-prey interactions within an arthropod community in the high-arctic tundra of Greenland, an area particularly affected by global warming. I focused on feeding interactions between the dominant wolf spider Pardosa glacialis, a generalist predator and its arthropod prey along an altitudinal gradient spanning 500 metres and representing different vegetation types and microclimates projecting future climate change. I found that the arthropod prey community indeed changes with elevation and vegetation structure, being dominated by soil-associated small species at low elevation and large flying species at high elevation. I then applied a newly developed assay to identify prey DNA in the gut content of more 600 individuals of Pardosa glacialis, collected along the same altitudinal gradient. Here I found that Pardosa feed on a wide spectrum of prey, encompassing 51 different arthropod prey families. However, the community of used prey consists of same prey groups, irrespective of elevation or environment. Pardosa predators are very conservative in their prey choice, favoring abundant groups in the insect order Diptera, such as non-biting midges and dark-winged fungus gnats. Interestingly, the preferences for Diptera could not be observed in feeding experiments under controlled laboratory conditions. The results indicate that environment does not control predator-prey interactions between Pardosa and its prey, nor does predator body size - a key factor in many other food web studies. However, prey phylogeny may explain most of the observed patterns, as Pardosa tend to feed on closely related prey groups within the order Diptera, sharing many traits such as body size, low sclerotization and behavior. The low importance of environmental in shaping predator-prey interactions has also been reported from two additional studies within the research fellowship in Zackenberg and Iceland, investigating spider prey community in areas of different vegetation types and soil temperatures. Both studies support the notion, that feeding interactions in Arctic habitats are relatively robust to environmental changes but may be challenged by changes in prey availability. Within this fellowship I was able to reveal underlying principles structuring predator-prey interactions of a model arthropod community and evaluate the effect of environmental and biological factors in shaping these. The results add important information how predators and whole animal communities will respond to climate change. Future studies however, need to focus on both, feeding and non-feeding interactions, such as competition, to understand the ecology of the highly interconnected arctic arthropod communities.
Publications
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(2019) Assessing changes in arthropod predator-prey interactions through DNA-based gut content analysis-variable environment, stable diet. Molecular ecology 28 (2) 266–280
Eitzinger, Bernhard; Abrego, Nerea; Gravel, Dominique; Huotari, Tea; Vesterinen, Eero J.; Roslin, Tomas
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(2017) Dissecting the interaction web of Zackenberg: targeting spider diet along environmental gradients. Zackenberg Ecological Research Operations: 21st Annual Report 2015. Hansen, J., Topp-Jørgensen E. & Christensen TR (eds.). Aarhus: Aarhus University, DCE – Danish Centre for Environment and Energy, Vol. 21, p. 69-71
Eitzinger B, Kankaanpää TT, Kaartinen RM, Abrego N, Ovaskainen OT & Roslin T
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(2018) High resistance towards herbivore-induced habitat change in a high arctic arthropod community. Biology Letters,14, 20180054
Schmidt NM, Mosbacher JB, Eitzinger B, Vesterinen EJ, Roslin TV
