Periodic Reporting for period 1 - PARAISO (Novel integrated experimental and analytical approaches to unravel parasitic interactions by stable isotope analyses)
Período documentado: 2022-09-01 hasta 2024-08-31
Parasites play an important role in food webs and the use of stable isotopes has been recently implemented to disentangle parasitic trophic interactions, specifically traditional bulk stable isotopes (bulk SIA, whole tissue analyses). However, these analyses show considerably high variability of the isotopic differences between parasites and their resources (i.e. their hosts), which can confound inferences regarding trophic interactions. A novel technique, the compound-specific stable isotope analysis of amino acids (hereafter CSIA-AA), might provide information on a more profound level (i.e. individual amino acids) and thus better characterize parasite-host relationships. The PARAISO project aims to make a significant contribution to our understanding of parasitic trophic interactions and their potential to affect the isotopic composition of infected hosts through an innovative integrated approach combining field sampling and laboratory feeding experiments with the simultaneous analysis of bulk SIA and CSIA-AA. This combination, applied to different parasite-hosts systems, will allow for determination of isotopic changes caused by dietary shifts versus parasitic infections, in both hosts and parasites. PARAISO is the first project to apply this novel interdisciplinary approach using cutting-edge technologies and thus will significantly advance our understanding of trophic transfer in parasite-host interactions.
Diet-switch experiments in two parasite-host systems have been performed, taking samples for stable isotope analyses (both bulk stable isotope analyses and compound-specific stable isotopes of amino acids) from both the host and the parasite. Isotopic differences between parasites and their hosts (i.e. trophic discrimination factors) as well as between infected and uninfected hosts have been calculated, two datasets have been produced and are now statistically being analyzed and prepared for publication. These datasets have been complemented by including field-based samples, which will help to understand naturally occurring stable isotope signals in parasite-host systems. Preliminary results suggest that the changes over time in 13C and 15N happen at different rates in infected and uninfected snails, i.e. the turnover time is different, especially in the digestive gland versus the muscle. This is likely caused by the presence of parasites, showing different stable isotope values in infected individuals, which could lead to potential errors in estimation of trophic niches and positions in food webs.
We also have developed a conceptual model to advance our understanding of trophic parasitic relationships, describing how changes in resource intake or internal resource use of hosts caused by parasites can lead to differences of trophic and isotopic niches of infected versus uninfected individuals and ultimately alter resource flows through food webs. This resulted in a publication in a leading parasitology journal (Trends in Parasitology, 39:749–759. 10.1016/j.pt.2023.06.003).
Furthermore, preliminary analyses have been presented at five conferences or scientific seminars, two other manuscripts are being prepared to present the obtained results, in addition to other manuscripts published during the project. The results have been also disseminated in several outreach activities, press releases and an interview.
We also have developed a conceptual model to advance our understanding of trophic parasitic relationships, describing how changes in resource intake or internal resource use of hosts caused by parasites can lead to differences of trophic and isotopic niches of infected versus uninfected individuals and ultimately alter resource flows through food webs. This resulted in a publication in a leading parasitology journal (Trends in Parasitology, 39:749–759. 10.1016/j.pt.2023.06.003).
Furthermore, preliminary analyses have been presented at five conferences or scientific seminars, two other manuscripts are being prepared to present the obtained results, in addition to other manuscripts published during the project. The results have been also disseminated in several outreach activities, press releases and an interview.
Our results provide insight into the impact of parasitic infections on organisms, potentially affecting their isotopic and trophic niches within food webs. The importance of including host-parasite relationships in ecological studies is therefore unquestionable, and this should serve as a base for future research plans, especially using stable isotopes in ecological studies. The fundamental knowledge gained during PARAISO can thus support the environmental assessment and sustainable management of organisms in ecosystems and help to understand the role of parasites in them.