Sex-specific asymmetry within the cloacal microbiota of the striped plateau lizard, Sceloporus virgatus

Abstract

The structure and diversity of microbial communities in wild vertebrate populations remain poorly understood, but are expected to have important consequences for individual survival and reproductive success. For instance, recent work has demonstrated that cloacal microbe assemblages of wild birds are related to the phenotypic quality of the host. To contribute to this field of study, we examined the composition and diversity of the cloacal microbiota of free-ranging striped plateau lizards, Sceloporus virgatus, using 16s rRNA-based culture independent techniques. Our dataset, generated from cloacal swabs of six males and six females, and based on twenty five 16s rRNA clones from each sample, revealed (i) low overall microbial diversity, (ii) a striking sex asymmetry in microbial community composition with males displaying cloacal microbiota more typical of gastrointestinal residents found in other organisms, while females display only gammaproteobacterial phylotypes, (iii) a significant sex difference in microbial community structure, with females having significantly lower microbial diversity and richness than do males, and (iv) that the diversity of the female microbial community is negatively correlated to her ectoparasitic mite load. It is not yet clear if the female-specific paucity of cloacal microbial diversity is due to host function or microbe-microbe interactions, or whether the relationship to female mite load is causal, however these findings are expected to have relevance to the species’ life history and ecology. Although the diversity of microbiota from humans, mice, birds, zebrafish, and invertebrates is widely investigated, this is one of only a few reports in the literature describing the cloacal microbiota of a wild vertebrate, and is perhaps the first report for wild reptiles that utilizes culture-independent techniques.