Resources from: Gut microbiome composition better reflects host phylogeny than diet diversity in breeding wood-warblers

Understanding the factors that shape microbiomes can provide insight on
the importance of host-symbiont interactions and on co-evolutionary
dynamics. Unlike for mammals, previous studies have found little or no
support for an influence of host evolutionary history on avian gut
microbiome diversity and instead have suggested a greater influence of the
environment or diet due to fast gut turnover. Because effects of different
factors may be conflated by captivity and sampling design, examining
natural variation using large sample sizes is important. Our goal was to
overcome these limitations by sampling wild birds to compare
environmental, dietary, and evolutionary influences on gut microbiome
structure. We performed fecal metabarcoding to characterize both the gut
microbiome and diet of fifteen wood-warbler species across a four-year
period and from two geographic localities. We find host taxonomy generally
explained ~10% of the variation between individuals, which is ~6-fold more
variation of any other factor considered, including diet diversity.
Further, gut microbiome similarity was more congruent with the host
phylogeny than with host diet similarity and we found little association
between diet diversity and microbiome diversity. Together, our results
suggest evolutionary history is the strongest predictor of gut microbiome
differentiation among wood-warblers. Although the phylogenetic signal of
the warbler gut microbiome is not very strong, our data suggest that a
stronger influence of diet (as measured by diet diversity) does not
account for this pattern. The mechanism underlying this phylogenetic
signal is not clear, but we argue host traits may filter colonization and
maintenance of microbes.