2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

����203 Jakub Rusek
Access to poor quality Daphnia samples – a novel SNP based approach
Authors: Jakub Rusek 1 , Patrick Turko 2 , Christoph Tellenbach 2 , Sabine Gießler 1 ,Piet
Spaak 2 , Justyna Wolinska 1
Affiliation: 1 Department of Biology II, Evolutionsoekologie, Ludwig-Maximilians-
University; 2 Eawag, Swiss Federal Institute of Aquatic Science and echnology,
Duebendorf, Switzerland Munich
Microsatellite genotyping of natural plankton populations is a well established
method for the identification of species and their hybrids in the Daphnia longispina
complex. However, we found these length-based markers unsuitable when analyzing
poor quality samples (such as historical or degraded samples). For example,
formaldehyde fixation, which fragments DNA, prevents amplification of longer DNA
fragments. SNP genotyping seems to be a good approach to overcome this problem,
due to the possibility of shorter fragment amplification. Furthermore, this method
allows not only high-throughput genotyping, but the calibration among laboratories
is also relatively precise. Therefore, we aim to develop a reliable method to identify
species of the D. longispina complex and their hybrids by SNP genotyping. After
comparing the D. galeata transcriptome with the D. pulex genome, we are selecting
several putatively informative genes and designing corresponding primers. Candidate
SNPs are being identified based on sequence information of all three species from
the D. longispina complex. To confirm the diagnostic value of these candidate SNPs,
we are using a set of genetically well-defined clones from species and hybrids
originating from diverse locations across Europe. For large-scale screenings we are
optimizing SNP detection via the SnaPshot Multiplex kit. By multi-locus SNP
genotyping we will be able to assess the population structures in long-term
formaldehyde preserved samples of a hybridizing species complex.
����204 Max Rabus
Uncovering hidden morphological defences in Daphnia magna - an interdisciplinary
approach to assess the predator-induced fortification of the carapace
Authors: Max Rabus 1 , Thomas Söllradl 1 , Hauke Clausen-Schaumann 1 , Christian
Laforsch 1
Affiliation: 1 Department of Biology II, Ludwig-Maximilians-University Munich
The cladoceran Daphnia magna has been shown to develop a bulky morphotype as
an effective inducible morphological defence against the predatory tadpole shrimp
Triops cancriformis. Mediated by kairomones, the daphnids express an increased
body length, -width and an elongated tail spine. In the present study we examined
whether these large scale morphological defences are accompanied by additional
‘hidden’ defences, i.e. a fortification of the exoskeleton. To obtain this goal we
employed atomic force microscopy to assess the hardness of the cuticle, we used
semi thin sections of the carapace to measure the cuticle thickness and finally, we
used fluorescence microscopy to analyse the diameter of the pillars connecting the
two carapace layers. We found that D. magna indeed expresses hidden
morphological defences against Triops predation. Thereby, the cuticle in induced
individuals is approximately five times harder and two times thicker than in control
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