Food availability affects the strength of mutualistic host–microbiota interactions in Daphnia magna

Abstract

The symbiotic gut microbial community is generally known to have a strong impact on the fitness of its host. Nevertheless, it is less clear how the impact of symbiotic interactions on the hosts' fitness varies according to environmental circumstances such as changes in the diet. This study aims to get a better understanding of host-microbiota interactions under different levels of food availability. We conducted experiments with the invertebrate, experimental model organism Daphnia magna and compared growth, survival and reproduction of conventionalized symbiotic Daphnia with germ-free individuals given varying quantities of food. Our experiments revealed that the relative importance of the microbiota for the hosts' fitness varied according to dietary conditions. The presence of the microbiota had strong positive effects on Daphnia when food was sufficient or abundant, but had weaker effects under food limitation. Our results indicate that the microbiota can be a potentially important factor in determining host responses to changes in dietary conditions. Characterization of the host-associated microbiota further showed that Aeromonas sp. was the most prevalent taxon in the digestive tract of Daphnia.

Diet and other environmental factors shape the bacterial communities of fish gut in an eutrophic lake

“…) followed by Aeromonadaceae , Arcicella , Flavobacteriaceae (Callens et al . ). Other studies have shown the microbiota of Daphniidae sp.…”

Life history and eco‐evolutionary dynamics in light of the gut microbiota

“…Evidence mainly comes from studies comparing germ-free to conventionally reared individuals, in particular in arthropods, which reveal that gut bacteria have an overwhelming influence on growth, development, reproduction and survival. In the fruit fly Drosophila melanogaster (Storelli et al 2011) and in the water flea Daphnia magna (Sison-Mangus et al 2015, Callens et al 2016, germ-free individuals develop more slowly and are smaller than conventional animals, while in mosquitoes, axenic larvae fail to develop beyond the first instar (Coon et al 2014). In all these species, inoculating axenic larvae with gut bacteria can restore a normal developmental rate (Storelli et al 2011, Coon et al 2014, Callens et al 2016.…”

“…In the fruit fly Drosophila melanogaster (Storelli et al 2011) and in the water flea Daphnia magna (Sison-Mangus et al 2015, Callens et al 2016, germ-free individuals develop more slowly and are smaller than conventional animals, while in mosquitoes, axenic larvae fail to develop beyond the first instar (Coon et al 2014). In all these species, inoculating axenic larvae with gut bacteria can restore a normal developmental rate (Storelli et al 2011, Coon et al 2014, Callens et al 2016. Mono-association studies in Drosophila (Shin et al 2011, Storelli et al 2011), mosquitoes (Coon et al 2014) and Daphnia (Peerakietkhajorn et al 2016) further identified single bacterial strains that are sufficient to recapitulate the natural microbiota growth-promoting effect.…”

“…Gut microbes are also not mutualistic in the truest sense; some of these organisms can be pathogenic to some extent, while others might directly interfere with mutualistic microbes (e.g. through toxins), and their status can change with environmental conditions (Callens et al , King et al ; Fig. ).…”

The Hologenome Across Environments and the Implications of a Host-Associated Microbial Repertoire

“…The hologenome theory provides functional explanations for the role of the microbiome in a Darwinian framework as it relates to speciation (Brucker and Bordenstein, 2012, 2013b) and potentially host fitness (e.g., Callens et al, 2016). A Lamarckian framework (Rosenberg et al, 2009), on the other hand, is complementary to this, as it details the mechanisms whereby microbes are acquired or lost during an organism's lifetime, and that the acquisition of a novel species or strain of microorganism may be integrated into the hologenome.…”