Fig. 7

Microbial similarities/dissimilarities of heterospecific foster juveniles with their genetic and foster families. A Heterospecific cross-fostering experiment. B Pairwise dissimilarity matrix (left) based on Bray–Curtis dissimilarities, illustrated for one bird. The numbers illustrated as X are the dissimilarity index, and the actual values range from 0 to 1, where samples with identical communities scored 0 and samples with the greatest differences scored 1. Violin plots (right) with embedded box plots comparing the distribution of pairwise dissimilarities between heterospecific foster juveniles and their genetic relatives (genetic mothers, fathers and siblings) and foster relatives (foster mothers, fathers and siblings) at 5, 10 and 35 dph. Significance differences between foster and genetic relatives were determined based on Wilcoxon rank-sum tests. The significance of the change in distance over time between the foster and genetic groups was determined by the Kruskal–Wallis rank-sum test followed by the post hoc Dunn’s test. Significance is highlighted for p values ≤ 0.05 (*), p ≤ 0.01 (**) and p ≤ 0.001 (***) after Bonferroni correction. C Estimated proportions of OTUs in the gut microbiota of heterospecific foster juveniles originating from genetic and foster relatives at 5, 10 and 35 dph based on SourceTracker2 analyses. This figure was created by Omar Castillo-Gutiérrez using bird illustrations designed by Sonja Engel, the copyright holder