Transgenerational phenotypic plasticity: Cardiorespiratory physiology of the parthenogenetic marbled crayfish as a model system

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The aim of this project is to investigate phenotypic plasticity (i.e. the formation of different phenotypes based on the same genotype) of physiological parameters of the cardiorespiratory system. It is hypothesized that phenotypic plasticity might represent an interim solution until evolutionary adaptation can take place. Thus, it can be regarded as important evolutionary phenomenon. As a model system, physiology of the cardiorespiratory system of the parthenogenetic marbled crayfish, Procambarus fallax f. virginalis, will be studied. This species, of which only females exist, produces genetically identical offspring and thus is well suited for studies on phenotypic plasticity. To trigger effects of phenotypic plasticity, individuals will be exposed to environmental stressors (hypoxia, increased temperature, pollution with polycyclic aromatic carbohydrates) during early development. In later stages, physiological parameters (heart rate, stroke volume, cardiac output, oxygen consumption) will be measured and compared to a control group (raised under optimal conditions). Heart rate, stroke volume and cardiac output will be determined using video sequences. Measurement of oxygen consumption will be done with special measurement chambers with an optical fluorescence oxygen-sensing system. Beside intragenerational effects of phenotypic plasticity, transgenerational inheritance of plastic physiological parameters (as is expected due to knowledge on such effects in other species) will be studied. To that end, the same physiological parameters will be measured in the offspring, which (other than the mother individuals) have not been exposed to the environmental stressors themselves. It shall be shown that phenotypic plasticity of cardiorespiratory physiology is an interesting phenomenon that can lead to adaptation to fast change of environmental conditions.