Extinction cascades partially estimate herbivore losses in a complete Lepidoptera-plant food web

University of California-Davis, Department of Entomology, 1 Shields Avenue, Davis, California 95616, USA.
Ecology (Impact Factor: 4.66). 08/2013; 94(8):1785-94. DOI: 10.1890/12-1075.1
Source: PubMed


The loss of species from an ecological community can have cascading effects leading to the extinction of other species. Specialist herbivores are highly diverse and may be particularly susceptible to extinction due to host plant loss. We used a bipartite food web of 900 Lepidoptera (butterfly and moth) herbivores and 2403 plant species from Central Europe to simulate the cascading effect of plant extinctions on Lepidoptera extinctions. Realistic extinction sequences of plants, incorporating red-list status, range size, and native status, altered subsequent Lepidoptera extinctions. We compared simulated Lepidoptera extinctions to the number of actual regional Lepidoptera extinctions and found that all predicted scenarios underestimated total observed extinctions but accurately predicted observed extinctions attributed to host loss (n = 8, 14%). Likely, many regional Lepidoptera extinctions occurred for reasons other than loss of host plant alone, such as climate change and habitat loss. Ecological networks can be useful in assessing a component of extinction risk to herbivores based on host loss, but further factors may be equally important.

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Available from: Florian Altermatt, Jan 21, 2015
    • "As such, there is considerable interest in developing predictive methods to anticipate the trophic interactions that might develop between introduced and native species before the introduction actually happens (NAS 2002, Briese 2003, Gilbert et al. 2012, Pearse and Altermatt 2013b, Pearse et al. 2013). There have been several efforts to conceptually define the factors that cause some novel trophic interactions to form while others do not (Verhoeven et al. 2009, Harvey et al. 2010, Sih et al. 2010, Pearse et al. 2013). In each of these cases, the likelihood of a novel interaction can be described by the host breadth of the exploiter, the exploitability (or, conversely, defense) of the exploited organism, and the match between those organisms. "
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    ABSTRACT: With increasing biotic introductions, there is a great need for predictive tools to anticipate which new trophic interactions will develop and which will not. Phylogenetic constraint of interactions in both native and novel food webs can make some novel interactions predictable. However, many food webs are sparsely sampled, or may include inaccurate interactions. In such cases, it is unclear whether modeling methods are still useful to anticipate novel interactions. We ran bootstrap simulations of host-use models on a Lepidoptera-plant data set to remove native trophic records or add erroneous records in order to observe the effect of missing or erroneous data on the prediction of interactions with novel plants. We found that the model was robust to a large amount of missing interaction records, but lost predictive power with the addition of relatively few erroneous interaction records. The loss of predictive power with missing records was due to inaccuracy in estimating phylogenetic distance between native and novel hosts. Removal of interaction records proportionally to their encounter frequency in the field had little effect on the loss of predictive power. Host-use models may have immediate value for predicting novel interactions from large, but sparsely sampled databases of trophic interactions.
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    • "Molecular methods (Wirta et al. 2014) can also improve our ability to detect species–specific interactions and overcome sampling issues. Finally, catalogues, databases and expert knowledge may be useful to better capture all potential interactions for applications more interested in specialization of fundamental niches (Pearse and Altermatt 2013). However, in addition to potentially changing the biological interpretation, all complementary information will likely only improve data "
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    • "The loss of even a single important food can have severe impacts. For example, Pearse and Altermatt (2013) used simulations and field data to demonstrate that loss of their host plant was a significant driver for extinctions of specialist herbivores among the Lepidoptera. Similarly, LoGiudice (2006) reported that the loss of American chestnut (Castanea dentata) was likely a contributing factor to extirpations and reductions of Allegheny woodrat (Neotoma magister) populations. "
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