Dynamics of the cecal microbial community of an extreme hibernator, the arctic ground squirrel

Abstract

Arctic ground squirrels (Urocitellus parryii) acquire most of their necessary energy stores (primarily fat, 5 to 45% increase) to survive hibernation during the 3 weeks preceding immergence. Studies in humans and mice show the gut microflora of obese individuals is efficient in extracting energy from carbohydrates and promotes host storage of triglycerides into adipose tissue, suggesting the gut microbiota of arctic ground squirrels may play an important role in pre‐hibernation fattening.. In order to study changes in gut microflora, cecal samples were collected from captive‐born juvenile squirrels at 4 time points (n=10) from weaning to hibernation. Mean squirrel mass increased linearly with age (R2= 0.9652), while mean abdominal white fat mass increased exponentially (R2 = 0.9982). Cecal content peaked at 6 weeks post‐weaning (15g ± 4.75). The percent live cells increased linearly from 63.31% ± 3.84 to 80.04% ± 5.00 throughout the active season (R2= 0.9989), while percent dead and injured cells decreased linearly, 28.77% ± 3.93 to 17.14% ± 5.67 and 7.87% ± 1.64 to 2.76% ± 0.84, respectively (R2= 0.9804 and 0.9899, respectively). These results suggest that microbial cell viability increases throughout development and pre‐hibernation fattening. Additional analyses conducted includes microbial community diversity using 16s rDNA genes, and short chain fatty acid analysis to investigate microbial activity.