Trophic and Non-Trophic Interactions in a Biodiversity Experiment Assessed by Next-Generation Sequencing

Abstract

Plant diversity affects species richness and abundance of taxa at higher trophic levels. However, plant diversity effects on omnivores (feeding on multiple trophic levels) and their trophic and non-trophic interactions are not yet studied because appropriate methods were lacking. A promising approach is the DNA-based analysis of gut contents using next generation sequencing (NGS) technologies. Here, we integrate NGS-based analysis into the framework of a biodiversity experiment where plant taxonomic and functional diversity were manipulated to directly assess environmental interactions involving the omnivorous ground beetle Pterostichus melanarius. Beetle regurgitates were used for NGS-based analysis with universal 18S rDNA primers for eukaryotes. We detected a wide range of taxa with the NGS approach in regurgitates, including organisms representing trophic, phoretic, parasitic, and neutral interactions with P. melanarius. Our findings suggest that the frequency of (i) trophic interactions increased with plant diversity and vegetation cover; (ii) intraguild predation increased with vegetation cover, and (iii) neutral interactions with organisms such as fungi and protists increased with vegetation cover. Experimentally manipulated plant diversity likely affects multitrophic interactions involving omnivorous consumers. Our study therefore shows that trophic and non-trophic interactions can be assessed via NGS to address fundamental questions in biodiversity research.

Plant diversity increases predation by ground‐dwelling invertebrate predators

“…, Tiede et al. ) would enable further insights into the mechanisms underlying the positive effects of plant diversity on predation rates reported here. Another interesting result from our field site is that omnivorous species tend to become more predatory along the plant diversity gradient (Ebeling et al.…”

“…Further experimental work using moving prey and predator individuals in combination with behavioral observations or using more sophisticated methods such as gut-content analysis (Roubinet et al 2015, Tiede et al 2016) would enable further insights into the mechanisms underlying the positive effects of plant diversity on predation rates reported here. Another interesting result from our field site is that omnivorous species tend to become more predatory along the plant diversity gradient .…”

A multitrophic perspective on biodiversity–ecosystem functioning research

“…, Naeem et al, 1994; Naeem and Li, 1997), the understanding of how multitrophic communities change their diversity and how this affects their functioning in terrestrial ecosystems remains limited (Eisenhauer et al, 2013; Haddad et al, 2009; Scherber et al, 2010). Moreover, terrestrial BEF research so far has virtually neglected the fact that primary producers do not function in isolation, but in a complex network of multitrophic, and also non-trophic interactions (Figure 2; Duffy, 2002; Hines et al, 2015b; Seabloom et al, 2017; Sobral et al, 2017; Tiede et al, 2016).…”

Gut microbiomes of mobile predators vary with landscape context and species identity

“…Thus, it is likely that at least some of the bacterial variation between lady beetle species was due to dietary differences maybe as a result of resource partitioning through differences in the dietary breadth, prey preferences, the ability to locate prey, preferred areas on a plant to forage, and the likelihood of switching habitats (Forbes & Gratton, 2011;Hodek & Honěk, 1996;Iperti, 1999;Schellhorn & Andow, 2005;Sloggett & Majerus, 2000). Studies that simultaneously identify food remains and microbes in gut contents (Paula et al, 2015;Tiede et al, 2016) could further illuminate the relation between diet and the gut microbiome.…”