Evolution of haemocyanin and its influence on thermal sensitivity in cold adapted cephalopods


Dr. Felix Mark 
Helmholtz-Zentrum für Polar- und Meeresforschung 
Sektion Integrative Ökophysiologie


Cephalopods are found in high abundance throughout all world oceans on a wide latitudinal cline from tropical into polar waters and are of considerable commercial importance. When the Southern Ocean formed 35 million years ago with the opening of the Drake Passage, endemic and newly invading species had to adapt to increasingly cold Antarctic waters in this altered habitat. Many octopod species are found among the successful groups in the Antarctic. After its formation process, the Southern Ocean has remained a stable habitat over evolutionary timescales, however, recent changes in thermal properties and ocean chemistry may prove challenging to these species. Therefore I propose to investigate the evolution of this Antarctic group in the light of changing climatic conditions and the radiation of cephalopods into the Southern Ocean. Temperature, pH and oxygen concentration are the three most important parameters that influence oxygen-binding capacities of cephalopod blood and for survival at nearly -2°C, a cephalopod requires a highly specialised blood-gas exchange. By using extracellular haemocyanin, cephalopods possess a less effective respiratory protein than fish (which have intracellular haemoglobin). In order to successfully compete with fish, cephalopods have developed a high level of haemocyanin adaptability. Despite their prominent position in Antarctic food webs and being highly abundant, very little is known about Antarctic octopod physiology in general and specifically of the role of haemocyanin as a mediator between the organism and an extreme environment. By means of an integrative physiological and molecular genetic approach, this study aims to shed light on the links between physiological adaptation and the phylogeny of octopodid haemocyanin during the adaptive radiation of these animals into Antarctic waters and to assist in explaining the recent biogeography of Antarctic octopods. Keywords: haemocyanin, physiological adaptation, evolution, Antarctica, octopod, cephalopod.


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