A Balard1; V H Jarquín-Díaz1; J Jost1; I Martincová4; 5; L Ďureje4; 5; J Piálek4; 5; M Macholán2; 3; J Goüy de Bellocq4; 5; S J Baird4; 5; E Heitlinger1;
1 Institute for Biology, Humboldt University Berlin, Germany; 2 Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Czech Republic; 3 Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Germany; 4 Institute of Vertebrate Biology, Czech Academy of Sciences, Czech Republic; 5 Institute of Vertebrate Biology, Czech Academy of Sciences, Germany
DiscussionDifferential parasite loads in hybrid hosts compared to parental species have been observed in various hybrid systems. Compared to host-parasite interactions within parental host, parasites encountering admixed, recombinant hosts for the first time in the centre of a host hybrid zone have been shown to reproduce less within the host for several nematodes. We hypothesize that this mechanism of hybrid vigour is general and can be found for parasites of various pathogenicity. We therefore assessed intracellular infections by Eimeria, a parasite of high pathogenicity, and infections by pinworms, assumed less pathogenic, and compared their intensity in two house mouse subspecies and their natural hybrids from a novel transect of the European hybrid zone. We found both lower parasite intensities in hybrid hosts than in parental mice and no evidence of a lower parasite prevalence in the centre of the hybrid zone, the latter disproving ecological epidemiological factors as responsible of the observed pattern. Using the same approach, we also corroborated hybrid vigour against pinworm infections reported in previous studies. We further questioned whether differences in body condition during infection would indicate different impacts on hybrid vs. parental hosts health, but couldn’t show such an effect. We argue that studying parasites in hosts hybrid zones provides a unique opportunity to study host-parasite interactions in two types of interactive states, namely long term and short term evolutive interactions.