Open Access Research article

Evolutionary divergence of the swim bladder nematode Anguillicola crassus after colonization of a novel host, Anguilla anguilla

Urszula Weclawski1*, Emanuel G Heitlinger1, Tobias Baust2, Bernhard Klar2, Trevor Petney1, Yu San Han3 and Horst Taraschewski1*

Author affiliations

1 Department of Ecology and Parasitology, Zoological Institute, Karlsruhe Institute of Technology, Kornblumenstrasse 13, Karlsruhe, Germany

2 Department of Stochastics, Karlsruhe Institute of Technology, Kaiserstrasse 89, Karlsruhe, Germany

3 Institute of Fisheries Science, College of Life Science, National Taiwan University, Taipei, Taiwan

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Citation and License

BMC Evolutionary Biology 2013, 13:78  doi:10.1186/1471-2148-13-78

Published: 8 April 2013



Anguillicola crassus, a swim bladder nematode naturally parasitizing the Japanese eel, was introduced about 30 years ago from East Asia into Europe where it colonized almost all populations of the European eel. We conducted a common garden experiment under a reciprocal transfer design infecting both European and Japanese eels with populations of A. crassus from Germany, Poland and Taiwan. We tested, whether differences in infectivity, developmental dynamics and reproductive output between the European and Asian parasite populations occur while harboured in the specimens of native and colonized eel host, and if these differences are genetically based or are plastic responses to the new environment.


Under common garden conditions an evolutionary change in the both European parasite populations of A. crassus compared with their Taiwanese conspecifics was observed for infectivity and developmental dynamics, but not for reproductive output. When infecting the European eel, current European populations of the parasite were less infective and developed faster than their Taiwanese conspecifics. In the reciprocally infected Japanese eel the genetically induced differences between the parasite strains were less apparent than in the European eel but higher infectivity, faster development and higher larval mortality of the European parasite populations could be inferred.


The differences in infectivity and developmental dynamics between European and Taiwanese populations of A. crassus found in our study suggest rapid genetic divergence of this parasite after a successful host switch in Europe.

Anguillicola crassus; Anguillicoloides crassus; Invasive; Host switch; Rapid evolution; Genetic divergence; Phenotypic plasticity