Fig. 1

Comparison of observed species richness (a) and Pielou’s evenness (b) between indoor- (blue) and outdoor-layers (red). Each box contains samples from a single poultry house. Each dot represents an individual chicken. Wilcoxon-Rank-Sum test were performed between indoor- and outdoor-layers. A lower value for Pielou’s evenness indicates less evenness in the microbial community of a sample