Seasonal glucocorticoid production correlates with a suite of small‐magnitude environmental, demographic, and physiological effects in mandrills

Abstract

The observed patterns suggest that plasticity in mandrills' metabolism in the form of glucocorticoid production allows them to adjust to predictable changes in climatic, demographic and physiological conditions by mobilizing and redirecting energetic resources toward appropriate, calibrated seasonal responses.

Faecal glucocorticoid metabolite profiles in diademed sifakas increase during seasonal fruit scarcity with interactive effects of age/sex class and habitat degradation

“…We defined the lean season based on a combination of reduced food availability, temperature and rainfall (Irwin et al , 2015). Seasonal glucocorticoid fluctuations can also occur in response to climate, such as rainfall (Carnegie et al , 2011; Gesquiere et al , 2008; Tecot, 2008; but see Rangel-Negrin et al , 2009) and temperature (Beehner and McCann, 2008; Charpentier et al , 2018; Weingrill et al , 2004), likely reflecting shifting metabolic demands associated with food availability as well as thermoregulation. Though we cannot isolate the effects of climate in our analysis, both phenology and observed variation in nutrient intakes (Irwin et al , 2015) corroborate the idea that seasonal food scarcity drives GC variation in sifakas.…”

Determinants of Variations in Fecal Neopterin in Free-Ranging Mandrills

“…Second, individuals exhibited higher nematode richness during the long dry season, especially the juveniles (Poirotte et al, 2016)-although our analyses show that gut parasites do not explain fecal neopterin levels. Third, the oxidative damages of females, including juvenile females, were found to be higher during the long dry season (Beaulieu et al, 2014), whereas their leucocyte profiles also varied seasonally, with lower lymphocyte proportion being observed during the long dry season, presumably because of the stress at that time of the year (Beaulieu et al, 2017) which is also characterized by increases in cortisol production compared to the long rainy season-although the highest cortisol concentrations are in fact observed during the short dry season (Charpentier et al, 2018). It is therefore likely that the long dry season poses a particular challenge on the immune system of juvenile mandrills, due to combined effects of nutritional stress and higher disease risk, which is reflected by the effect of the mating season (or proportion of cycling females) on neopterin levels.…”

“…We would expect most environmental seasonality to correlate with seasonal variations in rainfall in this equatorial region, where other aspects of environmental seasonality such as variations in day length or in temperature are tenuous. In addition, any social effect broadly linked with mandrill breeding seasonality, such as the influx of immigrant males during the mating season that induces a strong instability in the male hierarchy and may cause associated stress to other group members (Charpentier et al, 2018), is expected to co-vary with our male-male aggression variable. It remains possible that a physiological phenomenon affecting juveniles and restricted to the long dry season is responsible for this effect, and better captured by the proportion of cycling females than by rainfall patterns, which shows a bimodal distribution with two rainfall peaks a year.…”

“…In early 2018, the study population was composed of ca. 150 habituated individuals, including almost 90% of wild-born animals (see for details: Charpentier et al, 2018).…”

Same father, same face: deep-learning reveals paternally-derived signalling of kinship in a wild primate

“…Female dominance rank was evaluated using the outcomes of approach-avoidance interactions collected during focals or ad libitum observations and calculated using normalized David’s score (as per 43 ). We divided adult females into three categories of rank of similar size across the entire study period (high-ranking, medium-ranking, low-ranking).…”