The gut microbiome is important for digestion, host fitness, and defense against pathogens,
which provides a tool for host health assessment. Amphibians and their microbiomes
are highly susceptible to pollutants including antibiotics. We explored the role of
an unmanipulated gut microbiome on tadpole fitness and phenotype by comparing tadpoles
of Rana berlandieri in a control group (1) with tadpoles exposed to: (2) Roundup (R)
(glyphosate active ingredient), (3) antibiotic cocktail (enrofloxacin, sulfamethazine,
trimethoprim, streptomycin, and penicillin), and (4) a combination of Roundup and
antibiotics. Tadpoles in the antibiotic and combination treatments had the smallest
dorsal body area and were the least active compared to control and Roundup-exposed
tadpoles, which were less active than control tadpoles. The gut microbial community
significantly changed across treatments at the alpha, beta, and core bacterial levels.
However, we did not find significant differences between the antibiotic- and combination-exposed
tadpoles, suggesting that antibiotic alone was enough to suppress growth, change behavior,
and alter the gut microbiome composition. Here, we demonstrate that the gut microbial
communities of tadpoles are sensitive to environmental pollutants, namely Roundup
and antibiotics, which may have consequences for host phenotype and fitness via altered
behavior and growth.
