Effects Of Repeated Encounters On Behaviors And Physiological Status In Female Striped Field Mice (Apodemus Agrarius) And Striped Hamsters (Cricetulus Barabensis)

Striped field mice(Apodemus agrarius),living in a social lifestyle in the field,but striped hamsters(Cricetulus barabensis),living in a solitary lifestyle in the field,two species exhibited marked dominant-subordinate relationship among individuals,and,for females,behaviors,the body mass,physiological status and faecal hormones levels were related to lifestyle and inter-individual relationships.Total 56 adult female field mice and hamsters were captured from cropland of a mountainous area in southwest of Shandong province,and all experimental animals were individually housed in cages for 6 months.Based on matching in body mass, every two unfamiliar female mice were given an encounter within arena for 15 min.And female hamsters were matched 11 pairs,female field mice were matched 7 pairs.The faeces of each experimental mice were collected every day for 28 consecutive days.Our results showed that:1) Aggressive behaviors of dominant female hamsters were more higher than subordinate individuals,however,the subordinate mice kept defensive behaviors in highly steady levels. Aggressive behaviors of dominant female field mice were more higher than subordinate individuals,and kept highly steady levels in prophase but lower levels in anaphase;the subordinate mice kept the same trend as the dominant individuals.The intimate behaviors were the same frequency between dominant and subordinate in field mice.Aggressive,defensive, nonsocial,behaviors were significant difference in two species.2) Body mass of dominant female hamsters increased significantly,and the body mass of 4 w encouters also kept the same trend;the field mice body mass had the trend as hamsters,but were not significant difference in dominant,subordinate mice.Body mass in two female species were not significant difference.3) Adrenal gland index of dominant hamsters decreased significantly,and more lower than control,Adrenal gland index of dominant in field mice were more lower than subordinate groups,and ovary index of dominant groups were more higher than control groups.Adrenal gland,ovary,uterus,index were reached significant difference in two species.4) The faecal cortisol and estradiol concentrations of two female species fluctuated significantly with time lapse,but the difference was insignificantly between dominant and subordinate individuals.Cortisol and estradiol concentrations of faeces in both two species reached significantly differential levels.5) The faecal cortisol levels correlated positively and significantly with estradiol levels of dominant female hamsters,the faecal cortisol levels and estradiol levels in dominant, subordinate,control groups of striped field mice were not reached significant correlation.6) Aggressive behaviors correlated negatively with faecal cortisol concentrations among the dominant female hamsters after initial encounters,however,aggressive behaviors,were not correlated with faecal cortisol concentrations among the dominant female striped field mice after initial encounters.Our data implied that repeated encounters did not affect the survival and potential reproduction capabilities of female striped hamsters,which might be attributed to the solitary lifestyle of this species;but repeated encounters affected the survival and potential reproduction capabilities of female striped field mice,which might be attributed to the social lifestyle of this species.