Urbanization and altitude impact on gut microbiome of an Andean frog (Pristimantis unistrigatus)

The analysis of the intestinal microbiome in amphibians provides insights of the anthropogenic environmental impact. Pristimantis unistrigatus is an Andean amphibian species whose distribution has been recorded in Ecuador and Colombia, ranging from endemic elfin forests to urban gardens. In this study, we focus on the analysis of the P. unistrigatus microbiome 16S rRNA gene sequencing. A total of 32 specimens of P. unistrigatus were collected and analyzed from 4 locations in the Valley of Quito, Ecuador, characterized by several urban environments and altitudes. The results show that the relative abundance of bacteria is significantly different amongst groups. Clostridiales are proportionally more abundant in rural and lower altitude locations, while Erysipelotrichaceae, Desulfovibrionaceae, Enterobacteriaceae, Bacteroidaceae and Lachnospiraceae are found at higher elevations. These results highlight the importance of the evolution of the microbiome as a tool of adaptation and survival of amphibians in the present-day changing ecosystems undergoing anthropogenic stresses. Importance Amphibians constitutes one of the groups most vulnerable to environmental alterations. Due to their sophisticated reproductive and breeding requirements and their permeable skins to breathe, amphibians are compulsively studied as ecological indicators. The destruction of pristine habitats occurred all over the planet in recent decades has caused a catastrophic decline in amphibian populations for many species everywhere. Ecuador, being one of the most biodiverse country on Earth, hosts a huge variety of amphibians, thus offering a unique possibility of studying the biology of the amphibian species living in its ecosystems, and how they adapt to changing habitats. A direct way to diagnose the status of an amphibian population is to study the gut microbiome of the individual specimens. The gut microbiome is closely related to the host’s health and so to its ability to adapt and survive. An important output of this study is to offer indications and tools useful to conservation programs before irreversible damages are caused to the habitats and the amphibians’ populations still thriving in them.