Microbes are potential key players in the evolution of life histories and aging inCaenorhabditis elegans

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.

The archaeal classNitrososphaeriais a key player of the reproductive microbiome in sponges during gametogenesis

“…The mucous layer in the cephalopod Octopus vulgaris exhibits a sex-specific symbiosis in which microbes benefit from easy access to distinct substrates present in female and male skin, respectively (Rodríguez-Barreto et al 2024). Another example is the nematode Caenorhabditis elegans, where bacteria exhibit sex-specific effects, leading to differential developmental rates in males and females (Santos et al 2023). While sex-specific microbiomes could be the result of sexual size dimorphism or to sex-specific differences in habitat selection (Bates et al 2023), different physiological demands of the reproductive process in each sex might also be behind the divergence in their microbiomes.…”