Assessing changes in arthropod predator–prey interactions through DNA‐based gut content analysis—variable environment, stable diet

Abstract

Analysing the structure and dynamics of biotic interaction networks and the processes shaping them is currently one of the key fields in ecology. In this paper, we develop a novel approach to gut content analysis, thereby deriving a new perspective on community interactions and their responses to environment. For this, we use an elevational gradient in the High Arctic, asking how the environment and species traits interact in shaping predator-prey interactions involving the wolf spider Pardosa glacialis. To characterize the community of potential prey available to this predator, we used pitfall trapping and vacuum sampling. To characterize the prey actually consumed, we applied molecular gut content analysis. Using joint species distribution models, we found elevation and vegetation mass to explain the most variance in the composition of the prey community locally available. However, such environmental variables had only a small effect on the prey community found in the spider's gut. These observations indicate that Pardosa exerts selective feeding on particular taxa irrespective of environmental constraints. By directly modelling the probability of predation based on gut content data, we found that neither trait matching in terms of predator and prey body size nor phylogenetic or environmental constraints modified interaction probability. Our results indicate that taxonomic identity may be more important for predator-prey interactions than environmental constraints or prey traits. The impact of environmental change on predator-prey interactions thus appears to be indirect and mediated by its imprint on the community of available prey.

Spider webs, stable isotopes and molecular gut content analysis: Multiple lines of evidence support trophic niche differentiation in a community of Hawaiian spiders

“…Nevertheless, significant interspecific and inter‐clade differences in isotopic signature persist when datasets are controlled for year and elevation (Figures S1 and S2). Interestingly, another recent study found that spiders' diets do not change over elevational gradients despite differences in the prey community over these gradients (Eitzinger et al, ), though isotopic differences due to climatic variation may still occur between different elevations.…”

Table for five, please: Dietary partitioning in boreal bats

“…We used a single primer pair (SFF‐145f: 5′‐GTHACHGCYCAYGCHTTYGTAATAAT‐3′ and SFF‐351r: 5′‐CTCCWGCRTGDGCWAGRTTTCC‐3′; primers and PCR setup from Walker, Williamson, Sanchez, Sobek, & Chambers, ) to test the DNA extraction success in the pooled samples and confirm the bat species by molecular analysis and another primer pair to amplify the potential prey (ZBJ‐ArtF1c: 5′‐AGATATTGGAACWTTATATTTTATTTTTGG‐3′ and ZBJ‐ArtR2c: 5′‐WACTAATCAATTWCCAAATCCTCC‐3′; primers and PCR setup from Zeale, Butlin, Barker, Lees, & Jones, ). Despite the proposed bias in Zeale primers toward Diptera and Lepidoptera (Clarke, Soubrier, Weyrich, & Cooper, ), we chose these for several reasons: (a) These are the most widely applied markers, (b) many species have been detected using exactly the same primers, even though claimed to be nonamplifiable in the earlier criticism, and (c) we wanted to allow comparison of our results with those of other studies using the same primers (Clare et al, ; Kaunisto, Roslin, Sääksjärvi, & Vesterinen, ; Koskinen et al, ; Krüger, Clare, Greif, et al, ; Krüger, Clare, Symondson, et al, ; Vesterinen et al, ; Wirta et al, ; Eitzinger et al, ). The PCR and library construction closely followed Kaunisto et al (), except we used MyTaq HS Red Mix (product nr BIO‐25048, Bioline, UK) polymerase throughout the protocol.…”

“…We focused sampling on roosts inhabited by a single species, and likewise, we intended to pool pellets from a single species into a single pooled sample. In total, we initially sampled 1,252 fecal pellets from the five bat species in this study ( we wanted to allow comparison of our results with those of other studies using the same primers Kaunisto, Roslin, Sääksjärvi, & Vesterinen, 2017;Koskinen et al, 2018;Krüger, Clare, Greif, et al, 2014;Vesterinen et al, 2013Vesterinen et al, , 2016Wirta et al, 2015;Eitzinger et al, 2018). The PCR and library construction closely followed Kaunisto et al (2017), TA B L E 1 Information on the sampling details and characteristics of the field and molecular data.…”

From feces to data: A metabarcoding method for analyzing consumed and available prey in a bird‐insect food web

“…Molecular dietary analysis-sequencing prey DNA from predator feces or gut contents and identifying them using a reference library (Clare et al, 2009;Eitzinger et al, 2018;Symondson, 2002;Vesterinen et al, 2016;Zaidi, Jaal, Hawkes, Hemingway, & Symondson, 1999)-can be used to reveal the exact food webs in ecosystems. Molecular dietary analysis-sequencing prey DNA from predator feces or gut contents and identifying them using a reference library (Clare et al, 2009;Eitzinger et al, 2018;Symondson, 2002;Vesterinen et al, 2016;Zaidi, Jaal, Hawkes, Hemingway, & Symondson, 1999)-can be used to reveal the exact food webs in ecosystems.…”