Abstract
Microbes can have profound effects on host fitness and health and the appearance of late-onset diseases. Host-microbe interactions thus represent a major environmental context for healthy aging of the host and might also mediate trade-offs between life-history traits in the evolution of host senescence. Here we have used the nematode Caenorhadbitis elegans to examine whether host-microbe interactions might modulate the evolution of host life-history and aging. We first characterized the effects of two non-pathogenic Escherichia coli strains, a pathogenic E. coli strain and a pathogenic Serratia marcescens strain on the reproductive schedule and survival of an outbred C. elegans population, to be used in an experimental evolution study. Secondly, to investigate the dependency of these effects on host genotype, we assayed population growth rates and survival of five representative C. elegans inbred strains in response to these microbes. Our results show that host-microbe interactions have a substantial, host-genotype-dependent impact on reproductive effort and survival of the nematode host. Although pathogenic bacteria reduced host survival, as expected, they did not necessarily decrease host fertility or population growth rate. Given such microbe-specific genotypic differences in host life history, we predict that the evolution of reproductive schedules and senescence in this system might be critically contingent upon host-microbe interactions, a hypothesis which we will be testing using experimental evolution in future work.
Competing Interest Statement
The authors have declared no competing interest.