Stable isotopes of Hawaiian spiders reflect substrate properties along a chronosequence

PeerJ

article

Susan R. Kennedy¹  Todd E. Dawson¹  Rosemary G. Gillespie¹ 

[1] Department of Environmental Science, Policy and Management, University of California;Department of Integrative Biology, University of California

关键词: Nutrient cycling;    Stable isotopes;    Chronosequence;    Arthropods;    Spiders;    Nitrogen;    Trophic niche;   

DOI  :  10.7717/peerj.4527

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

The Hawaiian Islands offer a unique opportunity to test how changes in the properties of an isolated ecosystem are propagated through the organisms that occur within that ecosystem. The age-structured arrangement of volcanic-derived substrates follows a regular progression over space and, by inference, time. We test how well documented successional changes in soil chemistry and associated vegetation are reflected in organisms at higher trophic levels—specifically, predatory arthropods (spiders)—across a range of functional groups. We focus on three separate spider lineages: one that builds capture webs, one that hunts actively, and one that specializes on eating other spiders. We analyze spiders from three sites across the Hawaiian chronosequence with substrate ages ranging from 200 to 20,000 years. To measure the extent to which chemical signatures of terrestrial substrates are propagated through higher trophic levels, we use standard stable isotope analyses of nitrogen and carbon, with plant leaves included as a baseline. The target taxa show the expected shift in isotope ratios of δ15N with trophic level, from plants to cursorial spiders to web-builders to spider eaters. Remarkably, organisms at all trophic levels also precisely reflect the successional changes in the soil stoichiometry of the island chronosequence, demonstrating how the biogeochemistry of the entire food web is determined by ecosystem succession of the substrates on which the organisms have evolved.

【 授权许可】

CC BY