Temperature-dependent benefits of bacterial exposure in embryonic development of Daphnia magna resting eggs

Abstract

The environments in which animals develop and evolve are profoundly shaped by bacteria, which affect animals both indirectly through their role in biogeochemical processes and directly through antagonistic or beneficial interactions. The outcomes of these activities can differ according to environmental context. In a series of laboratory experiments with diapausing eggs of the water flea Daphnia magna, we manipulated two environmental parameters, temperature and presence of bacteria, and examined their effect on development. At elevated temperatures (≥26°C), resting eggs developing without live bacteria had reduced hatching success and correspondingly higher rates of severe morphological abnormalities compared with eggs with bacteria in their environment. The beneficial effect of bacteria was strongly reduced at 20°C. Neither temperature nor the presence of bacteria affected directly developing parthenogenetic eggs. The mechanistic basis of this effect of bacteria on development is unclear, but these results highlight the complex interplay of biotic and abiotic factors influencing animal development after diapause.

The microbiota of diapause: How host–microbe associations are formed after dormancy in an aquatic crustacean

“…If the necessary beneficial microbiota are transmitted by the parent into the resting stage, then the micro‐organisms can be considered a form of parental effect or a source of heritable nongenetic variation in their host (Badyaev & Uller, ; Zilber‐Rosenberg & Rosenberg, ). The occurrence of microbial transmission through resting stages would also support the often untested assumption that the microbial symbionts are deriving a benefit from the association (Mushegian & Ebert, ), since host and symbiont reproduction would be linked across host generations. Where the host is dependent on acquiring beneficial microbes from the environment after dormancy, we would expect low taxon‐specificity in the host–microbe association, because selection would disfavour reliance on specific microbes whose presence is not guaranteed in the environment where hatching occurs.…”

The Mercury-Tolerant Microbiota of the Zooplankton Daphnia Aids in Host Survival and Maintains Fecundity under Mercury Stress

“…A similar report also showed that a Pseudomonas strain isolated from a D. magna host is beneficial to the development of D. magna resting eggs at warm conditions. 84 Under mercury stress, lower survival rates were observed for the three mercury-treated groups when compared to their counterparts at the end of the assay (day 18): Bac-Suppl + Hg (43%, n = 13/30), Pse-Inf + Hg (70%, n = 21/30), and Bac- Free + Hg (60%, n = 18/30). Daphnids from the Bac-Suppl + Hg were most severely affected under mercury stress (χ 2 = 17.22, p < 0.0001) while the survival rates of Pse-Inf + Hg daphnids were statistically similar to those of Pse-Inf daphnids (χ 2 = 2.18, p = 0.14).…”

Genomic characterization of selfing in the cyclic parthenogen Daphnia magna

“…We kept four genotypes of D. magna (Table 1), naturally collected from Algeria, Israel, Russia and Spain, as isofemale lines under standard laboratory conditions, as described by Mushegian et al., (2016). Under favourable conditions, Daphnia reproduce asexually (i.e.…”