Social relationships and social structure of the mound-building mouse ( Mus spicilegus ) in intraspecific cage groups

Abstract

The social relationships of Mus spicilegus were studied in intraspecific cage groups for a month during the reproductive period to clarify the role of intraspecific aggressiveness in shaping social structure and in reproduction. The mound-building mice were captured from a wild population in northern Bulgaria. A total of 13 groups, 5 male, 4 female, and 4 male-female groups, were tested. Each group consisted of five unfamiliar adults. The experiments were carried out in 100100-cm glass cages. The patterns of behaviour and the dominantsubordinate structure within each group were investigated. A dominance index for every individual in the group was calculated. During the period of establishment of the hierarchical structure in the groups a high level of aggressiveness was registered among individuals. About half of the subdominants and subordinates were found dead, with or without obvious marks of injury. Male-male interactions were more aggressive compared to these of females. Dominant-subordinate relationships between individuals of the same sex were observed in the mixed groups. A link between dominance rank and reproduction was established. The dominant male and the dominant female formed a pair and started to breed. Based on these findings it can be assumed that the aggressiveness of M. spicilegus is an adaptation to its life in the fields, where dominance is likely to be an essential factor in individual reproductive success. It is likely that the successful rearing of offspring in natural populations, which are exposed to strong biotic and abiotic impact, necessitates the existence of monogamous relationships.

Socio-genetic structure of mound-building mice, Mus spicilegus, in autumn and early spring

“…In the present study, males were trapped in low density, sometimes paired with one or several females. Although the monogamous system in this species has been ascertained by experiments conducted in the laboratory (Patris & Baudoin, 1998Patris et al, 2002), in outdoor enclosures (Dobson & Baudoin, 2002;Baudoin et al, 2005), and in open field studies (Suchomelova, Munclinger & Frinta, 1998;Simeonovska-Nikolova, 2003), only 18% of the females were found to be paired with a male. The number of monogamous pairs is probably higher: some solitary females were pregnant (Gouat et al, 2003b), which may indicate that we were unable to capture the male.…”

“…Indeed, a stable pair bond between partners has been demonstrated both in the laboratory and in semi-natural enclosures (Patris & Baudoin, 1998;Dobson & Baudoin, 2002;Simeonovska-Nikolova, 2003;Baudoin et al, 2005). Other species of the Mus genus are commonly considered as polygamous-polygynous species, but monogamy in M. spicilegus is further supported by two arguments: the first being bi-parental care (Patris & Baudoin, 2000), with an efficient implication of the male in parental care (Féron et al, 2007).…”

Male-female associations and female olfactory neurogenesis with pair bonding in Mus spicilegus

“…Laboratory studies on M. spicilegus have revealed behaviour that suggests a monogamous mating system (Patris & Baudoin, 1998, 2000; Patris et al ., 2002; Simeonovska‐Nikolova, 2003). The first aim of this study was to test the prediction of stable male–female associations during the period of reproduction, an expectation for a monogamous mating system.…”

“…In a field study, Simeonovska‐Nikolova & Gerasimov (2000) found no overlap between female home ranges during the breeding period. Our observations in enclosures revealed a high level of aggression between females, as described during dyadic encounters (Patris et al ., 2002) and in cage groups of wild mice (Simeonovska‐Nikolova, 2003). This lack of cooperation between females during the reproductive period may also exist between sisters (this study).…”

“…The mating system and spatial organization of this species are not clearly known. Several recent results from the laboratory suggest a socially monogamous mating system: the existence of a male–female pair bond (Patris & Baudoin, 1998), paternal behaviour and cooperation of parents in caring for their young (Patris & Baudoin, 2000), and a high level of aggression during encounters between unfamiliar mice, whether males or females (Patris et al ., 2002; Simeonovska‐Nikolova, 2003). The latter could indicate an exclusive use of space by bonded pairs in natural populations.…”