Decline in parasite diversity promoted by lower host densities in Lake Tanganyika
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| Year of publication | 2016 |
| Type | Conference abstract |
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| Description | Lake Tanganyika is a remarkable freshwater ecosystem characterised by high stability and a diversified fauna. Surprisingly, despite their high importance in ecosystems, parasites have been overlooked in most of the investigations but are getting more and more attention over the last years. A recent study revealed radiation events of monogenean parasites promoted by host speciation in the littoral zone. Monogeneans mainly occurring on freshwater and marine fishes and usually display strong host specificity related to their direct life cycle and long co-evolutionary processes. The main purpose of our study was testing diversity and speciation patterns of monogeneans infecting deepwater cichlids in the lake. In total, all eight representatives of the Bathybatini tribe were examined for monogenean infection. Morphological identification was based on parasite sclerotized structures. Geomorphometrics provided a visualization of the complex shape variation as an additional view to classical morphometrics. Molecular analyses were performed by means of established markers with different rates of molecular evolution preparing a dataset for population genetic approaches. Apparently, six out of eight studied cichlids are infected by a single monogenean species called Cichlidogyrus casuarinus. Significant morphological intraspecific variation related to host preference. On the other hand, no differentiation on the genetic level was documented. Monogeneans therefore have not followed speciation events of their hosts indicating an adaptation to lower host densities in this type of habitat. Our results support the previous suggestion of a decrease of parasite host specificity in the deepwater zone and form the first observation of this pattern in a freshwater ecosystem. |
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