A possible evolutionary lag in the relationship between freshwater mussels and European bitterling
The coevolutionary dynamics between European bitterling Rhodeus amarus and freshwater unionid mussels, which the former parasitize by laying eggs on their gills, were tested. In a series of experiments fish preferences and mussel responses were compared in parasites and hosts of recent (Europe) and ancient (Asia) sympatry. Rhodeus amarus readily oviposited on the gills of all mussel species tested. Fish that laid their eggs on the gills of Asian Anodonta woodiana, however, suffered a dramatic reduction in reproductive success compared to fish that oviposited on the gills of European mussels: Unio pictorum, Unio tumidus, Anodonta anatina and Anodonta cygnea. This difference was the result of egg ejection behaviour by mussels rather than the unsuitability of the internal gill environment for European bitterling embryo development. The ejection response of mussels with a long sympatry with European bitterling was considerably more pronounced than that of mussels with a substantially shorter sympatry. The data support a coevolutionary arms race between bitterling and mussels and point to an evolutionary lag in the relationship between R. amarus and its European mussel hosts.
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Document Type: Regular Paper
Department of Ecology & Vertebrate Zoology, University of Łodź, Banacha 12/16, 90-237 Łodź, Poland
Centre for Marine Studies, University of Queensland, Brisbane, Queensland 4072, Australia
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, P. R. China
Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, U.K.
Publication date: 2007-03-01