Impact of intraspecific variation in insect microbiomes on host phenotype and evolution

Abstract

Microbes can be an important source of phenotypic plasticity in insects. Insect physiology, behaviour, and ecology are influenced by individual variation in the microbial communities held within the insect gut, reproductive organs, bacteriome, and other tissues. It is becoming increasingly clear how important the insect microbiome is for insect fitness, expansion into novel ecological niches, and novel environments. These investigations have garnered heightened interest recently, yet a comprehensive understanding of how intraspecific variation in the assembly and function of these insect-associated microbial communities can shape the plasticity of insects is still lacking. Most research focuses on the core microbiome associated with a species of interest and ignores intraspecific variation. We argue that microbiome variation among insects can be an important driver of evolution, and we provide examples showing how such variation can influence fitness and health of insects, insect invasions, their persistence in new environments, and their responses to global environmental changes.

Comparative metagenomic study unveils bacterial communities and their putative involvement in ecological success of two pine-feedingIpsbeetle holobionts

“…In contrast, pests, including bark beetles and their associated microbiota, can successfully invade host trees by compromising host defence (25). The insect microbiota is often influenced by the diet, sex, life stages, and the environment and facilitates the expansion of the ecological and evolutionary potential of their hosts (63,64). There has been growing interest in understanding the role of insect-microbial association in shaping the plasticity of insects in recent times.…”

Immigration delays but does not prevent adaptation following environmental change: experimental evidence

“…Recently, it has been shown that plasticity in insects can be mediated by associated microbes (Kolodny & Schulenburg, 2020). Variation in the microbial communities in host insects is high (Lange et al, 2023), and the microbial community can evolve, which can facilitate persistence in new and challenging environments (Kolodny & Schulenburg, 2020). Microbes, therefore, can serve as an important source of adaptive phenotypic plasticity (Kolodny & Schulenburg, 2020;Ghalambor et al, 2007).…”

“…Microbes, therefore, can serve as an important source of adaptive phenotypic plasticity (Kolodny & Schulenburg, 2020;Ghalambor et al, 2007). Insect-associated microbes can be transmitted from parent to offspring (Lange et al, 2023), indicating that plasticity could be multi-generational. If the microbial community influences fitness in the presence of deltamethrin, it is possible that plasticity and adaptation in the microbiome helped facilitate the observed increase in growth rate during the rescue experiment.…”

“…A second consideration is that the common environment generation could have masked differences in growth rates, if they were initially caused by plasticity. As described above, microbiome-mediated phenotypic plasticity could have contributed to the increase in growth rate in the rescue experiment (Lange et al, 2023). If microbiome-mediated plasticity drove performance, the generation in a common environment prior to the reciprocal transplant experiment would have alleviated selection pressure and reduced the ability of the experimental populations to tolerate the insecticide.…”

Phylosymbiosis and metabolomics resolve phenotypically plastic and cryptic sponge species in the genus Agelas across the Caribbean basin

“…Ascertaining how microbes influence host diversification first requires a better understanding of how microbial composition and function reflects intraspecific variation in hosts (e.g. morphological, genetic and geographical; Evans et al., 2021; Kelly et al., 2021; Lange et al., 2023).…”