2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

expectations their parental species. Thus, we conducted an experiment to test for the
ability of ‘super clone’ to outcompete other hybrids. Different clones, isolated from
10 quarry lakes around Munich have been assigned randomly in five different groups
of 15 clones (5 D. longispina, 5 D. galeata, 4 of their hybrids and one clone of a
different Claderoceran species from the same lakes). These experimental
communities have been kept for ten weeks to measure the changes in community
composition.
We expect that the experimental communities will become dominated by a single
clone in the F1 hybrids but not in the parental taxa. This is because most of the
hybrids show extreme phenotypes and thus are poorly adapted to local
environments. But also a few genotypes might be especially fit and so would be a
successful competitor. The studied quarry lakes were created and thus opened for
colonization only about 20 years ago, our work might then contribute to a knowledge
how hybrid-specific traits may facilitate the colonization of novel habitats.
S�15 Christian Laforsch R513 / 17:15
Stealth mechanism or predator confusion? The exact defensive mechanism of
protective helmets in Daphnia
Authors: Christian Laforsch, Johannes Aman
Affiliation: 1 University Bayreuth
Inducible defences are strategies for coping with predation in heterogeneous
environments. In recent years conspicuous and often dramatic morphological
plasticity of several waterflea-species of the genus Daphnia has been found. For
instance helmets proved to be protective against predatory invertebrates. However,
the exact defensive mechanisms of the protective traits remained elusive. We used
high-speed camera video analysis to study the exact defensive mechanism of
protective helmets. Our study showed that helmet formation in Daphnia cucullata
leads to a wrong strike distance estimation in Chaoborus larvae. Chaoborus larvae
either completely miss their target or they only could catch a part of their prey item.
Given that Chaoborus larvae detect their prey with mechanoreceptors; our results
suggest that the protective traits alter the flow field around Daphnia. While our study
questions the current paradigm for the defensive mechanism, the ‘anti-lock-and-key
hypothesis’, it does not rule out, that multiple effects, incompatibility with the
predator mouthparts, an increased mechanical stability of their armour, and a altered
flow field act synergistically.
S�16 Kathrin Otte R513 / 17:30
Proteomic analysis of predator-induced phenotypic plasticity in Daphnia magna
Authors: Kathrin A. Otte 1 , Thomas Fröhlich, Georg J.Arnold, Christian Laforsch
Affiliation: 1 Department of Biology II, Ludwig-Maximilians-University Munich
Inducible defences have evolved under specific ecological conditions: spatial or
temporal variation in predation risks, availability of reliable cues indicating the threat,
possibility to form effective defences within a relatively short time span, and an
association of costs that can be saved when defences are not required. Inducible
232