2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

(e.g. production of sexual eggs in later generations). However, even when
Cyanobacteria were the only available food, they sustained the growth and
reproduction of Daphnia for five generations. The elevated temperature can
intensify the negative influence of Cyanobacteria on Daphnia (e.g. the highest
number of individual which did not reproduce in later instars was observed in the
presence of Cyanobacteria at higher temperature).
����212 Quirin Herzog
Reversibility of inducible defenses in Daphnia barbata
Authors: Quirin Herzog 1 , Carmen Tittgen 1 , Christian Laforsch 1
Affiliation: 1 Dep. Biol. II, Evolutionary Ecology, LMU München
Predator-Prey interactions are among the most common interspecific interactions in
nature. Due to spatial or temporal heterogeneity in predation risks, many prey
organisms respond with so-called inducible defenses. To evolutionary favor this type
of phenotypic plasticity over permanent defenses, they have to imbue costs, which
can be saved in the absence of a predator. Depending on the nature of these costs
(i.e. formation or running costs) these inducible defenses themselves are expected to
be either persistant or reversible, when not required anymore. Despite intense
research on inducible defenses in a variety of organisms the aspect of reversibility
has been widely neglected. So far, the same is true for the genus Daphnia, which has
been extensively studied in the context of inducible defenses. Here we test Daphnia
barbata, which displays a wide array of morphological defenses for reversibility of
these traits. We used two different invertebrate predators (Triops cancriformis and
Notonecta glauca), which cause predator-specific changes in the same traits (i.e.
helmet, tail spine, dorsal ridge) in D. barbata. By comparing the reversibility and
constancy of defensive structures depending on the predator, our results may
indicate the relevance of reversibility regarding the evolution of phenotypic plasticity.
����213 Linda Weiss
Neurophysiology of Inducible Defenses in Daphnia
Authors: Linda C. Weiss 1 , Christian Laforsch 2 , Ralph Tollrian 1
Affiliation: 1 Department of Animal Ecology, Evolution and Biodiversity, Ruhr University
Bochum; 2 Department of Biology II, Ludwig-Maximilians-University Munich
The immense ability of the model crustacean Daphnia to phenotypically adapt to
changing biotic and abiotic environmental conditions has eminent impacts on
freshwater ecosystems and their dynamics. Its ecological importance has been
intensively described throughout the past century. Progression on genome structure
and differential gene expression in unstable environments has been made since the
sequencing of the genome in 2007. Nevertheless, information on the underlying
cellular and neuronal mechanisms that are responsible for differential gene
expression and the resulting phenotypic adaptations is sparse. This study focused to
unravel the cellular and neuronal mechanisms underlying phenotypic plasticity in
Daphnia.
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