Contribution of host-specific microbiota to host fitness revealed by a microbiota transplantation experiment among the genotypes of an asexual animal species

The taxonomic composition of the host-associated microbiota is known to influence host fitness, which in turn is regulated by both environmental conditions and host genetic constraints. If hosts regulate genetically their microbiota to increase their fitness, it is likely that having a different type of host-associated microbiota should affect the fitness of that host. To test such a possibility, we experimentally transplanted host-associated microbiota between two genetically distinct genotypes of obligate parthenogenetic Daphnia cf. pulex, a freshwater zooplankton, with compositionally different host-associated microbiota. These genotypes were first sterilized and received the microbiota from the same or different host genotypes. We then examined the growth and reproduction rates and the taxonomic composition of the host-associated microbiota of these genotypes.