Diet affects arctic ground squirrel gut microbial metatranscriptome independent of community structure

Abstract

Summary We examined the effect of diet on pre-hibernation fattening and the gut microbiota of captive arctic ground squirrels (Urocitellus parryii). We measured body composition across time and gut microbiota density, diversity, and function prior to and after five-weeks on control, high-fat, low-fat (18%, 40%, and 10% energy from fat, respectively), or restricted calorie (50% of control) diets. Squirrels fattened at the same rate and to the same degree on all diets. Additionally, we found no differences in gut microbiota diversity or short chain fatty acid production across time or with diet. Analysis of the gut microbial transcriptome indicated differences in community function among diet groups, but not across time, and revealed shifts in the relative contribution of function at a taxonomic level. Our results demonstrate that pre-hibernation fattening of arctic ground squirrels is robust to changes in diet and is accomplished by more than increased food intake. Although our analyses did not uncover a definitive link between host fattening and the gut microbiota, and suggest the squirrels may possess a gut microbial community structure that is unresponsive to dietary changes, studies manipulating diet earlier in the active season may yet uncover a relationship between host diet, fattening and gut microbiota.

Implications of being born late in the active season for growth, fattening, torpor use, winter survival and fecundity

“…Also, LB individuals fasted twice a week and experiencing a gradually decreasing T a gained mass at an even higher rate than ad libitum fed animals ( Giroud et al, 2012 ). These results are also in line with previous studies on other hibernating species ( Dark, 1984 ; Dark et al, 1986 ; Hatton et al, 2017 ). For instance, arctic ground squirrels that were calorie restricted by 50% during 5 weeks of pre-hibernation fattened at the same rate and reached similar amount of fat reserves to ad libitum fed individuals ( Hatton et al, 2017 ).…”

“…These results are also in line with previous studies on other hibernating species ( Dark, 1984 ; Dark et al, 1986 ; Hatton et al, 2017 ). For instance, arctic ground squirrels that were calorie restricted by 50% during 5 weeks of pre-hibernation fattened at the same rate and reached similar amount of fat reserves to ad libitum fed individuals ( Hatton et al, 2017 ). Also, golden-mantled ground squirrels with restricted pre-hibernation food intakes underwent similar increases of body mass and possessed equivalent amounts of abdominal white adipose tissue as animals fed ad-libitum ( Dark, 1984 ).…”

Characterization of faecal and caecal microbiota of free-ranging black-tailed prairie dogs (Cynomys ludovicianus) using high-throughput sequencing of the V4 region of the 16S rRNA gene

“…This study employed 16S rRNA gene sequencing for characterization of the faecal and caecal microbiota. A study by Hatton et al . (2017) explored diet’s influence on the arctic ground squirrels’ microbiome and employed both 16S rRNA gene sequencing and metatranscriptomic analysis.…”

Advances and Challenges in Metatranscriptomic Analysis

“…Metatranscriptomic approaches have also been adapted to better understand the microbiomes of other animals, such as cattles (Mann et al, 2018; Sollinger et al, 2018; Li et al, 2019), squirrels (Hatton et al, 2017), and birds (Marcelino et al, 2019). Many studies in cattle microbiomes are focused on understanding the rumen microbiota to mitigate the release of potent greenhouse gas methane from livestock and increase feed efficiency.…”