Social relationships in Mastomys huberti as deduced from field and genetic analyses of multiple capture data

摘要

Multiple captures (i.e., the simultaneous capture of two or more individuals in the same trap) in rodent populations provide useful information on their social structure. Adding genetic analyses to these data enables to describe social links between individuals at a finer level. Here, we analyze the distribution and composition of multiple captures obtained during a 3-year study of a population of the murid rodent Mastomys huberti in Mali. In total, 133 multiple captures were recorded, representing more than 17% of the total number of individual capture events. Seasonal variations in the incidence of multiple captures were observed, and the young (classified as juveniles or subadults) were involved in multiple captures more often than expected. Juveniles (< 21 g) were captured together more often than expected, suggesting that they usually forage in groups. This trend was also observed in subadults (< 31 g), accompanied by a clear deficit of captures involving one subadult and one adult of the same sex, especially in males. This pattern could illustrate a phase when negative intraspecific interactions occur, possibly linked to dispersal of subadult males. Genotypic characterization of a significant fraction of the population using 11 microsatellite loci enabled to show that individuals caught together were significantly more closely related than those involved in single captures, even when close from each other. A seasonal trend of relatedness of these co-captured animals was also confirmed.