PS 7-96 - Parental care contributes to vertical transmission of microbes in a skin-feeding and direct-developing caecilian

Abstract: The current evidence of vertical microbiome transmission in amphibians is limited, with most studies indicating that only a limited proportion of the parental skin bacterial community is shared with their offspring. Yet those amphibian species investigated so far exhibit a limited form of parental care that does not include obligate attendance of juveniles. This hampers our understanding of how parental care impacts bacterial transfer from parent to offspring. Here, we assess bacteria transmission in Herpele squalostoma, an oviparous direct-developing caecilian in which females obligately attend juveniles that feed on their mother’s skin. We used 16S rRNA amplicon-sequencing of the skin and gut of wild H. squalostoma individuals (males, females, including those attending juveniles) as well as environmental samples. Our analyses revealed that juveniles obtain an important portion of their skin and gut bacteria communities from their mother. The contribution of a mother’s skin to the skin and gut of her respective juveniles was much higher than that of any other bacterial source. In contrast to males and non-attending females, only the skins of juveniles and their mothers were colonized by the bacteria taxa Verrucomicrobiaceae, Nocardioidaceae, and Erysipelotrichaceae. In addition to providing indirect evidence for microbiome transmission linked to parental care among amphibians, our study points to noticeable differences between the skin and gut communities of H. squalostoma and those of many frogs and salamanders. Our study is the first to find strong support for vertical bacteria transmission attributed to parental care in a direct-developing amphibian species, and suggests that obligate parental care promotes microbiome transmission in caecilians.