Theme 1: Morphological variation in Gastropods under extreme stress

Leonie Marschner
(H.-R. Köhler)

During embryonic development, external stress factors like metal exposure or heat can lead to increased morphological variation in organisms. Without stress, developmental pathways are quite stable, and it has been shown that stress proteins help stabilizing embryonic development and thus reduce morphological variation in plants and animals. When organisms are subjected to stress during their embryonic development, this process of canalization is disrupted and, consequently, more – previously hidden – variability is visible in the phenotype. In my PhD thesis I investigate how the noble metal platinum affects embryonic development in the snail Marisa cornuarietis. Exposure to platinum has been shown to lead to severe morphological rearrangements of organs in caenogastropod and pulmonate snails. Combining platinum with other stressors like heat leads to a gradual phenotypic variation that increases or decreases depending on the intensity of the respective stressors. This observation has lead to the hypothesis, that rising temperatures gradually induce the expression of stress genes and that the corresponding stress proteins gradually stabilize the developmental pathways until the disruptive platinum effect is reversed.