De rol van parasieten bij de soortvorming van hun gastheren.

Parasitism represent one of the most successful mode of life in nature. Parasites are widespread, potentially infecting all free-living species, and an important component of ecosystems. Since they have a close relationship with their hosts, parasite can influence host growth, reproduction, behaviour and survival. Hosts evolve strategies to resist to the parasite attack, while parasites counter-attack by evolving new specialisations. This arms race between parasites and their hosts may promote host speciation. Cichlid fish of Lake Victoria are a good group in which study whether parasites drive or contribute to host speciation. Tiziana Gobbin analysed infection patterns of closely related cichlid populations co-occurring in the same location. She found support for two prerequisites for parasite-mediated selection: host species differed in their infection profiles and such infection differences were maintained over multiple sampling years. Parasites selected different microhabitat locations on gills depending on the host species infected. This variation in microhabitat “preference” may be another trait indicating parasite-mediated selection. Thus, Gobbin suggest to include it in future studies. Infection differences accumulate as hosts become more genetically differentiated, but only hosts that do not hybridize in the wild (i.e. are already considered different species) display a significant difference in infection. This suggests that parasites may contribute to host divergence but they are not initiating it.

Dissertation: http://hdl.handle.net/11370/1f23eeae-35e1-4672-813a-07b34c66f410