Correlates of maternal glucocorticoid levels in a socially flexible rodent

• Published in: Hormones and behavior Vol. 116; p. 104577
• Main Authors: Pinho, Gabriela M., Ortiz-Ross, Xochitl, Reese, Andrew N., Blumstein, Daniel T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2019
• Subjects: Aggression - physiology; Animals; Animals, Newborn; Cort-fitness hypothesis; Feces - chemistry; Female; Glucocorticoid hormones; Glucocorticoids - metabolism; Litter Size; Male; Marmot; Marmota - metabolism; Marmota - physiology; Maternal Behavior - physiology; Mothers; Network metrics; Reproduction - physiology; Reproductive success; Rodentia - physiology; Social Behavior; Social stress; Social behavior; Glucocorticoid hormones; Marmot; Network metrics; Cort-fitness hypothesis; Reproductive success; Social stress
• ISSN: 0018-506X; 1095-6867
• DOI: 10.1016/j.yhbeh.2019.104577

While it is generally accepted that social isolation has detrimental effects on social species, little is known about the importance of social interactions in less social species–particularly for wild reproductive females. We studied socially-flexible yellow-bellied marmots (Marmota flaviventer) and asked whether features of the social environment are associated with maternal fecal glucocorticoid metabolite (FGM) concentrations. Since changes in maternal baseline glucocorticoids may have positive or negative consequences for offspring fitness, we were also interested in estimating their relationship with measures of reproductive success. We fitted generalized linear mixed effects models to a dataset including maternal FGM measurements, social network metrics, maternal/alloparental care, and pup FGM and survival. Agonistic interactions were positively associated with maternal FGM levels, while mothers that engaged in relatively more affiliative interactions had reduced FGM levels when living in environments with low predator pressure. Pups associated with mothers exhibiting high FGM levels had low annual survival rates, received less maternal/alloparental care and had higher FGM levels. Interestingly, offspring from mothers with high FGM levels were more likely to survive the summer when born in small litters. In sum, social interactions likely influence and are influenced by glucocorticoid levels of facultatively social females. Potential benefits of social bonds may be context-specific, and agonistic interactions may be tightly correlated with fitness. Female marmots exhibiting high FGM levels had overall low reproductive success, which is predicted by the cort-fitness hypothesis. However, under adverse conditions, offspring summer survival can be maximized if pups are born in small litters. •Social conditions and glucocorticoid levels (GC) are related in less social species.•The association between maternal GC and affiliative bonds is context-specific.•Females with high GC have pups with low overwinter and annual survival.•Pup summer survival can be maximized when females with high GC have small litters.•Our results are congruent with the predictions of the cort-fitness hypothesis.