Meeting Abstract
Bergmann’s rule is the observation that animals at more extreme latitudes have a larger body mass compared to animals at lower latitudes, presumably reflecting an adaptation to colder climates. Recent advances in microbial ecology have demonstrated that the obesity-associated microbiome can provide greater energy extraction from a diet by breaking down indigestible plant polysaccharides and promoting fat storage. To what extent gut microbes play a role in adaptive body size variation remains largely unexplored. Here, we combined field and laboratory based approaches (1) to understand the environmental and genetic factors associated with the gut microbial variation, and (2) to test the function of gut microbiome in relation to host body size variation. We characterized the gut microbial composition of 17 natural populations of house mice (Mus musculus) across North and South America using 16S amplicon sequencing. The overall microbial variation was correlated with climatic variables, body size, diet (carbon and nitrogen stable isotopes), and host genetic distance (exome capture data). We identified host genomic regions associated with microbial measurements using Latent Factor Mixed Models. We show a positive correlation between obesity-associated microbiome (i.e. greater ratio of Firmicutes and Bacteroidetes) and latitude, a consistent pattern with humans. In addition, we found microbial diversity measurements positively correlate with body size, both in wild and lab populations. Fecal transplant experiments are being conducted to understand the causal role of gut microbes in Bergmann’s rule, a fundamental pattern in evolutionary biology.
