Sex differences in postprandial blood glucose and body surface temperature are contingent on flight in the fruit bat, Cynopterus sphinx

Abstract

The postprandial blood glucose level is very high for the body size in frugivorous bats. Like other homeotherms, bats release heat during digestion of dietary macronutrients. Despite males and females of the same species exhibiting different foraging behaviour, empirical support for sex-differences in blood glucose and body surface temperature in fruit bats is poor. Moreover, while flight affects postprandial metabolism, whether such effects are different in each sex of fruit bats is unclear. Here, we studied these questions in the fruit bat, Cynopterus sphinx. We first assessed whether there are sex differences in the postprandial level of blood glucose and body surface temperature over time in rested bats. We then assessed whether flight affects outcomes of sex-differences in both traits. We found that the estimated marginal means of both traits were generally higher in females than males, in rested bats. Notably, the sex-difference in both traits was only significant at specific sampling time of the assay. Further, the trait means significantly differed between the sexes only in the rested, but not active, bats. Meaning that signals of sex-difference in metabolic traits eroded when bats were active. Taken together, our findings suggest that in C. sphinx, the sex-specificity in the expression of metabolic traits is significantly dependent on physical activity.

Transmissible cancer influences immune gene expression in an endangered marsupial, the Tasmanian devil (Sarcophilus harrisii)

“…Calculating one full factorial model with all the explanatory variables listed above, as well as their two‐way interaction would result in overparametrisation. Therefore, we excluded all interactions that did not include DFTD and with the remaining main effects and interactions, determined which explanatory variables and interactions were associated with variation in each gene using the function “dredge” within the package MuMIn (Barton, 2020; Loukola et al, 2020; Nagarajan‐Radha & Devaraj, 2021) which evaluated models with all possible combinations of explanatory variables and logical two‐way interactions while respecting the marginality constraints (i.e., no interactions are tested without also including their main effects in the model). Models were ranked and given a weight according to akaike information criterion (AICc) adjusted for sample size.…”

Baseline of Physiological Body Temperature and Hematological Parameters in Captive Rousettus aegyptiacus and Eidolon helvum Fruit Bats

“…These findings are in line with previous reports regarding sex-related differences in GLU levels of R. aegyptiacus ( Moretti et al, 2021 ). However, significantly higher levels of GLU in female compared to male individuals was verified for Cynopterus sphinx ( Nagarajan-Radha and Devaraj, 2021 ), a pteropodid bat of similar size and diet like R. aegyptiacus . This variation between seemingly closely related species possibly originates from differing sampling timepoints.…”

“…This variation between seemingly closely related species possibly originates from differing sampling timepoints. C. sphinx bats were sampled during the roosting period after foraging ( Nagarajan-Radha and Devaraj, 2021 ). E. helvum and R. aegyptiacus bats in this study were sampled in the morning, prior to being fed.…”