Is the socio-spatial distribution of mound-building mice, Mus spicilegus, compatible with a monogamous mating system?

International audienceWe tested whether the socio-spatial distribution of mound-building mice, Mus spicilegus, could be compatible with a monogamous mating system as suggested by several behavioural laboratory studies. A five day trapping session took place in an agricultural field in the Gyöngyös region (Hungary) at the end of April 2000. The species was identified through genetic techniques based on the microsatellite locus Musmcka. In total 43 animals were captured, and recapture rate was high (6/10 for males, 17/33 for females). Out of the 33 captured females, 17 were pregnant. Animals were generally recaptured in the same trap. Spatial associations (animals captured in the same trap) were observed between a male and a female (six cases) but also between females (six pairs and two trios) with or without a male. Based on these results we questioned the occurrence of monogamy and we proposed that polygyny could occur at least during the beginning of the reproductive season and in this studied population. Female biased sex-ratio and high population density may have favoured polygyny. However, associations between females could have resulted from the development of strong social bounds during the six months spent together during winter inside the mound. A possible consequence is that polygyny might be restricted to the over-wintering generation

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

International audienceMus spicilegus has become a popular biological model species in the last decade because of the evolutionary interest of its behavioural particularities (the building of mounds, bi-parental care and monogamous mating system). The genetic structure of M. spicilegus populations should reflect those life-history traits. Although many studies have reported on mound-building mouse populations in the field or in a semi-natural enclosure, only one used hyper variable genetic markers to assess parentage and social structure. In the present study conducted in Hungary, we analysed individuals from seven highly populous mounds in autumn with the set of loci used in a previous study. Our results confirmed that mounds are inhabited by juveniles from several parental units, but revealed population differences. In a capture–recapture field session in spring, we assessed genetic relationships between individuals after dispersal from the mounds, the other key moment of the life cycle of this species. The results indicate that the social structure at this moment reflects a transition phase between the large over-wintering groups and the monogamous pairs described later in the year. Social bounds forged during the long winter cohabitation may have lasting effects on social and genetic structure of this species. This scenario is discussed in respect of the available literature on this species as well as other species

Panel 1 - The Global Regulatory Landscape in Antitrust

Antitrust has received renewed attention from politicians worldwide recently. Discussions on market and monopoly power, both local and globally, have emerged at the center of political debates. For example, one of the first significant measures of the new federal administration in the U.S. was to pass an Executive Order to promote competition in the American Economy in 2021. Although the U.S. continues to play a significant role in shaping competition policy worldwide unequivocally, the European Union has recently emerged as a powerhouse in matters of competition law enforcement and competition policy. The rise of the Chinese antitrust laws could play an essential role in the future of antitrust discussions that one should consider. This panel will touch base with discussions on recent trends in global antitrust. Panelists would focus on how the American antitrust policy has shaped international debates and how other jurisdictions\u27 stances have influenced internal U.S. antitrust policies if they did so in the first place. The panel will also discuss specific policy questions, such as comparing the recent developments of the U.S.’ leniency and cartel enforcement programs with other nations. Finally, panelists will discuss if the U.S. still holds a prominent position as a lighthouse guiding infant antitrust agencies searching for guidance in competition policy matters

Panel 1 - The Global Regulatory Landscape in Antitrust

Antitrust has received renewed attention from politicians worldwide recently. Discussions on market and monopoly power, both local and globally, have emerged at the center of political debates. For example, one of the first significant measures of the new federal administration in the U.S. was to pass an Executive Order to promote competition in the American Economy in 2021. Although the U.S. continues to play a significant role in shaping competition policy worldwide unequivocally, the European Union has recently emerged as a powerhouse in matters of competition law enforcement and competition policy. The rise of the Chinese antitrust laws could play an essential role in the future of antitrust discussions that one should consider. This panel will touch base with discussions on recent trends in global antitrust. Panelists would focus on how the American antitrust policy has shaped international debates and how other jurisdictions\u27 stances have influenced internal U.S. antitrust policies if they did so in the first place. The panel will also discuss specific policy questions, such as comparing the recent developments of the U.S.’ leniency and cartel enforcement programs with other nations. Finally, panelists will discuss if the U.S. still holds a prominent position as a lighthouse guiding infant antitrust agencies searching for guidance in competition policy matters