Project Details
Projekt
Inducible chemical defences in primary producer - herbivore interactions: effects on population dynamics as a function of consumer trait diversity
Applicant
Professor Eric von Elert, Ph.D.
Subject Area
Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
Term
from 2014 to 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 257173517
Chemical defences are a major class of inducible defences in plant-herbivore interactions. Despite being wide spread, they have not yet been investigated for their effects on population dynamics in predator-prey systems. Here we use a planktonic system with a cyanobacterium as primary producer and with Daphnia as herbivore. The cyanobacterium Microcystis aeruginosa produces known protease inhibitors (PIs) as anti-herbivore defence that are induced upon exposure to actively grazing herbivores, which results in a feedback loop between grazing herbivores and the degree of defence at the primary producer level. This plastic trait defence at the primary producer level can be quantified by measuring the inhibitor content of the cyanobacterium. Here we use a co-culture with Daphnia magna to investigate how the inducible chemical defence of M. aeruginosa affects population dynamics at the level of primary producer and consumer and how the trait defence fluctuates. For comparison a non-defended cyanobacterium will be used. We further test how population dynamics and the trait defence are affected by trait variability at the consumer level by comparing a system with one versus a system with many D. magna genotypes that differ with respect to the trait tolerance to the PIs. We will run controlled growth experiments by varying a variety of parameters with the aim to quantify the trade-off of the trait defence at the primary producer level and to quantify the trade-off of the trait tolerance at the consumer level. We hypothesize that this herbivore-mediated induction of a chemical anti-herbivore defence feeds back on the consumer level. More specifically we anticipate that this inducible trait chemical defence in the cyanobacterium (i) strongly affects predator-prey cycles and leads to dampened population fluctuations of prey and predator abundances in comparison to an undefended cyanobacterium in a single prey-predator system. (ii) strongly affects predator-prey cycles in a system with many predators that differ in the trait tolerance. We expect that increasing trait-diversity at the consumer level will result in increased flexibility of reaction patterns (fluctuating/non-fluctuating) and therefore in increased system stability.
DFG Programme
Priority Programmes
Participating Person
Dr. Thomas Petzoldt
