Gut Microbiomes Allow Bears to Grow to Similar Sizes Despite Differing Diets

The gut microbiome composition of brown bears enables the animals to achieve similar sizes and fat stores even when having differing diets, according to a new study appearing in Scientific Reports this week. Given the variability in resources available in different regions at different times of the year, the gut microbiome is likely to play an important role in wildlife health and resilience. However, the vast majority of research into the microbiome has been conducted in humans and model organisms. To fill in this knowledge gap, a team led by scientists from Northern Michigan University used brown bears as an ecological model to understand the relationship between wildlife body condition metrics that are commonly used to assess health and gut microbiome community composition and structure. The researchers sequenced microbial DNA extracted from brown bear fecal samples collected at three different national parks across Alaska where the animals are known to have significantly different diets. They found no differences in gut microbiome composition among bears with differing body conditions nor any correlations between alpha diversity and body condition. "Our results indicate that [gut microbiome] composition reflects diverse foraging strategies while allowing brown bears to achieve similar body condition outcomes," the study's authors write.