Neotropical Frog Foam Nest's Microbiomes

Abstract

Amphibian foam nests are unique microenvironments that play a crucial role in the development of tadpoles. They contain high levels of proteins and carbohydrates, yet little is known about the impact of their microbiomes on tadpole health. This study provides a first characterization of the microbiome of foam nests from three species of Leptodactylids (Adenomera hylaedactyla, Leptodactylus vastus, and Physalaemus cuvieri) by investigating the DNA extracted from foam nests, adult tissues, soil, and water samples, analyzed via 16S rRNA gene amplicon sequencing to gain insight into the factors driving its composition. The results showed that the dominant phyla were proteobacteria, bacteroidetes, and firmicutes, with the most abundant genera being Pseudomonas, Sphingobacterium, and Paenibacillus. The foam nest microbiomes of A. hylaedactyla and P. cuvieri were more similar to each other than to that of L. vastus, despite their phylogenetic distance. The foam nests demonstrated a distinct microbiome that clustered together and separated from the microbiomes of the environment and adult tissue samples. This suggests that the peculiar foam nest composition shapes its microbiome, rather than vertical or horizontal transference forces. We expanded this knowledge into amphibian foam nest microbiomes, highlighting the importance of preserving healthy foam nests for amphibian conservation.

Keywords: bacteriome; biosurfactants; frog defenses; leptodactylidae; reproductive modes.

Figure 1

Geographical location of the collection sites; the square mark represents Fazenda Maceió-Taíba, and the triangle mark represents RPPN Monte Alegre.

Figure 2

Tricine-SDS-PAGE of 5 μg foam nest fluid from P. cuvieri (Pc), L. vastus (Lv), and A. hylaedactyla (Ad). Molecular weight (MW) range of 10 to 225 kDa. The most intense band in Lv, of 23.5 kDa, corresponds to Lv-ranaspumin as described in Hissa et al., 2014 [35].

Figure 3

Rarefaction curves for observed amplicon sequence variants (ASVs) in foam nests from neotropical frogs A. hylaedactyla, L. vastus, and P. cuvieri.

Figure 4

Relative abundance of bacteria and archaea amplicon sequence variants at phylum levels present in frog foam nests. Stacked bar plot of the relative abundance above 1%.

Figure 5

Relative abundance of bacteria and archaea amplicon sequence variants at the genus level present in frog foam nests. Stacked bar plot of the relative abundance above 10%.

Figure 6

Dendrogram generated via UPGMA clustering analysis using the amplicon sequence variants (ASVs) at bacterial genus level, showing the relationship among the frog species.

Figure 7

UPGMA cluster based on Bray–Curtis dissimilarities between bacterial amplicon sequence variants at the genus level presents in the foam nests, nest environments, and tissues of L. vastus.

Figure 8

Anuran foam nest microbiomes originate from the microbiome of the environment where these nests are deposited. However, certain groups of microorganisms are clearly enriched in nests compared to their natural environments. This suggests that these microorganisms may be beneficial to tadpoles in the early stages of development.