TY - JOUR
T1 - Parasites and stable isotopes
T2 - a comparative analysis of isotopic discrimination in parasitic trophic interactions
AU - Thieltges, David W.
AU - Goedknegt, M. Anouk
AU - O'Dwyer, Katie
AU - Senior, Alistair M.
AU - Kamiya, Tsukushi
N1 - Publisher Copyright:
© 2019 The Authors. This is an Open Access article
PY - 2019/9/1
Y1 - 2019/9/1
N2 - Stable isotopes are widely used to identify trophic interactions and to determine trophic positions of organisms in food webs. Comparative studies have provided general insights into the variation in isotopic composition between consumers and their diet (discrimination factors) in predator–prey and herbivore–plant relationships while other major components of food webs such as host–parasite interactions have been largely overlooked. In this study, we conducted a literature-based comparative analysis using phylogenetically-controlled mixed effects models, accounting for both parasite and host phylogenies, to investigate patterns and potential drivers in Δ13C and Δ15N discrimination factors in metazoan parasitic trophic interactions. Our analysis of 101 parasite–host pairs revealed a large range in Δ13C (–8.2 to 6.5) and Δ15N (–6.7 to 9.0) among parasite species, with no significant overall depletion or enrichment of 13C and 15N in parasites. As previously found in other trophic interactions, we identified a scaling relationship between the host isotopic value and both discrimination factors with Δ13C and Δ15N decreasing with increasing host δ13C and δ15N, respectively. Furthermore, parasite phylogenetic history explained a large fraction (>60%) of the observed variation in the Δ15N discrimination factor. Our findings suggest that the traditional isotope ecology framework (using an average Δ15N of 3.4‰) applies poorly to parasitic trophic interactions. They further indicate the need for a scaled rather than a fixed trophic discrimination factor framework along gradients of host δ15N. We also identified several conceptual and methodological issues which should to be considered in future research to help integrate parasitic interactions into a holistic isotope ecology framework across diverse trophic interactions.
AB - Stable isotopes are widely used to identify trophic interactions and to determine trophic positions of organisms in food webs. Comparative studies have provided general insights into the variation in isotopic composition between consumers and their diet (discrimination factors) in predator–prey and herbivore–plant relationships while other major components of food webs such as host–parasite interactions have been largely overlooked. In this study, we conducted a literature-based comparative analysis using phylogenetically-controlled mixed effects models, accounting for both parasite and host phylogenies, to investigate patterns and potential drivers in Δ13C and Δ15N discrimination factors in metazoan parasitic trophic interactions. Our analysis of 101 parasite–host pairs revealed a large range in Δ13C (–8.2 to 6.5) and Δ15N (–6.7 to 9.0) among parasite species, with no significant overall depletion or enrichment of 13C and 15N in parasites. As previously found in other trophic interactions, we identified a scaling relationship between the host isotopic value and both discrimination factors with Δ13C and Δ15N decreasing with increasing host δ13C and δ15N, respectively. Furthermore, parasite phylogenetic history explained a large fraction (>60%) of the observed variation in the Δ15N discrimination factor. Our findings suggest that the traditional isotope ecology framework (using an average Δ15N of 3.4‰) applies poorly to parasitic trophic interactions. They further indicate the need for a scaled rather than a fixed trophic discrimination factor framework along gradients of host δ15N. We also identified several conceptual and methodological issues which should to be considered in future research to help integrate parasitic interactions into a holistic isotope ecology framework across diverse trophic interactions.
KW - comparative analysis
KW - discrimination factor
KW - parasite–host interactions
KW - stable isotope analysis
KW - trophic fractionation
KW - trophic interactions
UR - http://www.scopus.com/inward/record.url?scp=85066048919&partnerID=8YFLogxK
U2 - 10.1111/oik.06086
DO - 10.1111/oik.06086
M3 - Article
AN - SCOPUS:85066048919
SN - 0030-1299
VL - 128
SP - 1329
EP - 1339
JO - Oikos
JF - Oikos
IS - 9
ER -