Introduction
Animals are associated with a diverse microbiome in their gut, which affects the host’s health, immunity, and metabolites of the host (Kinross et al., 2011). The composition of the gut microbiome may change with host development, diets, and surrounding environments of the host (Eckburg et al., 2005; Xu & Knight., 2015). Thus, gut microbiome may provide an important insight into ecology of host animals and be related to pathogen which can cause the zoonotic diseases (Andersen-Ranberg et al., 2018). However, to date, the gut microbiome researches have been primarily focused on human or captive animals, but gut microbiome and its related functions of wild animals remain poorly understood (Davidson et al., 2020).
In mammals, gut microbiome can be vertically transmitted since birth though parental care during lactation phase by direct delivery of maternal materials to offspring, so that it has a significant impact on the gut microbiome formation in early growth stage of the offspring (Chu et al., 2016; Wang et al., 2020). In a mouse model study, it has been reported that most microbiota genera had been vertically transmitted over generations (Moeller et al. 2018). In addition to the vertical transmission, diet is also a major factor to facilitate the gut microbiome formation. Microbiota can be also indirectly affected by diet acquisitions of new-borns in different food conditions provided by nursing mothers (Frese et al. 2015). Since the composition of a starter diet can vary among families, host diet can shape microbial structure and functions for digestion.
In this study, we investigated the feces of a wild herbivore from female adults and calves in the high Arctic environments, collected during the summer. The muskox (Ovibos moschatus ) is a large herbivore mammal that inhabits in the Arctic environments (Salgado-Flores et al., 2016). The dominant diets are willows (Salix spp.) in summer, graminoids (Carex , Eriophorum ) in winter (Gustine et al., 2014; Thing et al., 1987). Although the breeding season varies depending on the annual temperature (Schmidt et al., 2020), calves are usually born in April to May and start grazing from one week after birth, being closely attached to their mothers. Calves completely wean after one year (Adamczewski et al., 1994). By collecting fresh feces, the gut microbiomes and diet compositions were compared between the female adults and calves using bacterial 16S rRNA gene sequencing and stable isotopes analysis. Here we questioned 1) if muskoxen have different gut microbiomes with ages (female adults vs. calves) and 2) if the two age groups have similar diets.