Connecting taxonomy and ecology: Trophic niches of collembolans as related to taxonomic identity and life forms

Abstract Collembola are among the most abundant, diverse and functionally important groups of soil animals. Collembolans inhabit different litter and soil layers and their food objects are intimately related to their habitat. Morphological differences that separate high rank taxa of collembolans have clear functional meaning in relation to life style and habitat requirements (including position in the soil profile). However, no study has tested the hypothesis that the species within the major functional groups also differ in terms of trophic positions. This hypothesis was tested for the first time using stable isotope analysis. We compiled original and published data on the stable isotope composition of 82 collembolan species in temperate forest ecosystems. The δ 13 C and δ 15 N values of collembolans were found related to their life forms, reflecting a shift in available food objects across different habitat layers and matching the vertical isotopic gradient of soil organic matter. The trophic niche of species varied among different collembolan orders and families, indicating a pronounced phylogenetic signal and supporting the trophic niche conservatism hypothesis. Considering stable isotope compositions, as well as the taxonomic identity and life form of species, we outlined four collembolan functional guilds that use different types of food and perform different ecosystem functions.