Aggression and commensalism in house mouse: a comparative study across Europe and the near east

Abstract

Species specific differences of house mouse social behavior compared to its closest relatives (aboriginal species Mus macedonicus, Mus spicilegus, and Mus spretus) have recently been suggested. However, substantial variation of behavioral traits between mouse populations has been also evidenced. Agonistic behavior of laboratory-born house mice from five commensal populations (Mus musculus musculus: central Czech Republic, Mus musculus domesticus: Bulgaria, Greece, Turkey, and natural Mus m. musculus/domesticus hybrids from the Czech part of the hybrid zone) and five non-commensal populations of M. m. domesticus (C. Syria, E. Syria, Jordan, Iran, Libya) was studied. Dyadic interactions in a neutral cage were performed and the effects of sex and population on time spent by agonistic behavior evaluated. In all studied populations, the male-male interactions were more agonistic than the female-female ones. Male-male behavior gradually increased from the least agonistic population of M. m. musculus from Central Europe to the Near East populations of M. m. domesticus exhibiting the highest scores of agonistic behavior. Between-population differences were even stronger when female-female encounters were considered. While females of commensal populations belonging to both M. m. musculus and M. m. domesticus were tolerant of each other, those coming from non-commensal populations of M. m. domesticus were highly agonistic, reaching even the level of aggression between the females of some aboriginal mouse species. This phenomenon may be attributed to increased competition for food in non-commensal populations when compared to commensal ones supplied by superabundant resources. Social behavior of house mice, therefore, appears to be pliable rather than rigid and species specific. It can be changed rapidly according to ecological needs and such adaptability allows house mice to colonize various habitats. Aggr. Behav. 31:283-293, 2005. r

No postnatal maternal effect on male aggressiveness in wild-derived strains of house mice

“…This study is the extension of pilot experiments revealing conserved asymmetry in male aggressiveness between both strains representing M. m. musculus and M. m. domesticus [see also Pia´lek et al, 2008], that correspond to differences repeatedly reported from wild populations [Frynta et al, 2005;Thuesen, 1977;Van Zegeren and Van Oortmerssen, 1981;Volfova´et al, 2002], ancestral populations of the strains and populations along a transect across the Czech-Bavarian portion of the hybrid zone [Vosˇlajerova´and Pia´lek, unpublished data]. Even though the two subspecies and our model strains differ in many morphological and physiological parameters, we do not have any evidence and/or to our knowledge there is no study reporting subspecies-specific differences in hormonal levels or neurochemical differences that may lead to differences in aggressiveness.…”

“…Several studies have reported that two European subspecies of the house mouse, M. m. domesticus and M. m. musculus, differ markedly in levels of aggression, the former always winning dyadic encounters [Frynta et al, 2005;Pia´lek et al, 2008;Thuesen, 1977;Van Zegeren and Van Oortmerssen, 1981;Volfova´et al, 2002]. Unfortunately, most of the studies cited above are simple demonstrations of differences in aggression, with the exception of that by Volfova´et al [2002], who tested the idea that the differences in aggressiveness between these two subspecies are the result of genetic variation located on the Y chromosome.…”

Women infected with parasite Toxoplasma have more sons

“…As males of most rodent species are more exploratory (Frynta 1994), possess larger home ranges (e.g. Brown 1969), exhibit more aggression (Čiháková and Frynta 1996;Frynta et al 2005) and consequently (Krackow 2005) are more migratory (Pocock et al 2005) than conspecific females, we can speculate that overproduction of males by Toxoplasma-infected females may considerably facilitate long-range transmission of the infection in natural situation.…”

Influence of latent toxoplasmosis on the secondary sex ratio in mice

“…One form is acute toxoplasmosis, which in immunocompetent subjects, spontaneously turns into the second form, i.e. Č iháková and Frynta, 1996 ;Frynta et al 2005) and consequently the more dispersing sex (e.g. The latter is clinically asymptomatic, life-long infection characterized by the presence of anti-Toxoplasma antibodies in the blood and Toxoplasma bradyzoites in tissue cysts.…”