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Title: Microbes are trophic analogues of arthropods, mammals, and fish: Isotopic fingerprinting unites ‘green’ and ‘brown’ food webs

Author
item Steffan, Shawn
item CHIKARAISHI, YOSHITO - Japan Agency For Marine-Earth Science And Technology (JAMSTEC)
item DHARAMPAL, PRARTHANA - University Of Wisconsin
item CURRIE, CAMERON - University Of Wisconsin
item HORN, HEIDI - University Of Wisconsin
item PAULI, JONATHAN - University Of Wisconsin

Submitted to: International Congress of Entomology
Publication Type: Abstract Only
Publication Acceptance Date: 9/29/2016
Publication Date: 9/29/2016
Citation: Steffan, S., Chikaraishi, Y., Dharampal, P., Currie, C., Horn, H., Pauli, J. 2016. Microbes are trophic analogues of arthropods, mammals, and fish: Isotopic fingerprinting unites ‘green’ and ‘brown’ food webs [abstract]. International Congress of Entomology. Paper No. 2757.

Interpretive Summary:

Technical Abstract: This work addresses a cross-cutting issue within the field of food-web ecology—the integration of the microbiome into trophic hierarchies. The nature and degree to which microbes may reconfigure the trophic identities of carnivore and omnivore groups have remained surprisingly unresolved. This means that the trophic positions of the single most abundant, massive, and ubiquitous trophic group (detritivorous microbes) have not been measured with known, high accuracy. Using a ground-breaking molecular method (amino acid stable isotope analysis), we show that the presence of detritivorous bacteria and fungi in detrital food-chains elevates predictably the trophic positions of detritivorous fauna, including the detrital complex, itself. We not only provide accurate measurements of consumer trophic identity within detrital food-chains, but also illuminate the mechanisms by which microbes transform detritus from a non-living substrate into a food-web microcosm. Notably, we have demonstrated that 1) consumption of microbial ‘meat’ in brown food-webs elevates animal trophic position; 2) the mechanism driving this phenomenon is the degree to which microbes have consumed the detrital resource (conversion of detrital proteins into microbial proteins); 3) detritivory is actually omnivory among meso- and macro-fauna. Altogether, these findings should re-frame how ecologists interpret the trophic identities of the dominant global consumer group—detritivores. Our data reveal animal trophic identities in which microbial contributions have been fully integrated. In effect, we have united the macro- and microbiome in trophic ecology, facilitating comprehensive interpretations of trophic identity among omnivorous and carnivorous animals.