Abstracts - Deutsche Zoologische Gesellschaft

O DB.9 (Mo) - ENEvolution and development of the spider silk producing systemMaarten Hilbrant, Wim G.M. DamenInstitute for Genetics, University of CologneDevelopmental Biology Symposium 35The spider silk producing system comprises a complex set of different gland types ending in specializedappendages called spinnerets. Using these organs, spiders produce many different types ofsilk for a wide range of tasks, which is a unique trait in the animal kingdom. After the appearanceof the system at the base of the Araneae, extensive variation arose between the silk producing systemsof different spider lineages, and this was arguably of key importance for the success of spidersnowadays. Nevertheless, surprisingly little data is available on the developmental origin of thesestructures. We present here the first molecular data on the development of the spider silk producingsystem, in the model species Cupiennius salei. We tried to identify the primordia of the four differentsilk gland types. Confocal and SEM data suggest that the ampullate glands are derived from embryonicectodermal invaginations of the spinnerets. These invaginations are associated with expressionof an achaete-scute homolog, which may indicate involvement of this gene in ampullate silk glanddevelopment. The other silk gland types most likely develop during post-embryonic stages, and theirprimordia are currently being investigated. These studies will provide the basis for future inter-speciescomparisons and potentially could develop into a powerful evo-devo model of structures with aunique ecological significance.O EB.1 (Sa) - ENPlastic morphological responses to varying predation pressure in three-spinedsticklebacks (Gasterosteus aculeatus)Joachim G. Frommen 1 , Fabian Herder 2 , Leif Engqvist 1 , Marion Mehlis 1 , Julia Schwarzer 2 , Theo C.M. Bakker 1 , Timo Thünken 11Institut für Evolutionsbiologie und Ökologie, Universität Bonn; 2 Abteilung für Ichthyologie, ZoologischesForschungsmuseum Alexander Koenig, BonnTo understand the enormous phenotypic variation within and among populations is a major concernin evolutionary biology. Phenotypic variation is usually due to a combination of genetic and environmentalfactors. One environmental factor influencing individual fitness is predation. Prey organismstherefore evolved special anti-predator defenses in the presence of predators, often leading to phenotypicdifferentiation between populations. However, anti-predator traits are often costly to maintainund thus disadvantageous in predator-free environments. Three-spined sticklebacks are well-knownfor their morphological variation among populations. Recent studies have shown a strong geneticcomponent of variation in anti-predator morphology but the influence of plastic responses is lessunderstood. Here, we raised three-spined sticklebacks under different predator regimes using a splitclutchdesign. Sticklebacks growing in an environment simulating high predation risk grew significantlyfaster than their siblings kept under low or no predation risk. Adults from these treatmentsdiffered in their morphology, with fish from the high risk environment being more streamlined. Fishfrom the high predator-risk treatment developed greater spine asymmetries, maybe as a result oftheir increased growth rate. Thus, in addition to the well-documented genetic component of variationin stickleback morphology, phenotypic plasticity also contributes to variation within and amongpopulations.