Family Affairs and Experimental Male Replacement Affect Fecal Glucocorticoid Metabolites Levels in the Egyptian Spiny Mouse Acomys cahirinus
Abstract
In social animals, a temporary intrusion of an unfamiliar adult male into an established family group and/or male replacement may be accompanied by social stress. We performed experiments involving non-invasive monitoring of fecal glucocorticoid metabolites (GCMs) in 10 manipulated family groups (50 individuals in total) of the Egyptian spiny mouse Acomys cahirinus.
Study animals were kept in special apparatuses enabling individual collection of fecal samples without considerable disturbance to family group members. The results of this study revealed only limited effects of experimental male intrusion and/or removal on GCM levels.
Nevertheless, GCM levels of adult males sharply decreased following immigration into a new family group which provided them new breeding and social opportunities. We also found that there was no effect of age and only a partial effect of sex (males exhibited lower values) on baseline GCM levels.
In contrast, there were considerable and consistent differences in GCM levels among individual family groups. This finding suggests that differences in social settings among these groups were a more important source of variation in social stress.
Thus, we recommend that group identity should be taken into account in performing behavioral and physiological studies in social rodents.