Descriptionn group-living animals, males are typically assumed to be dominant over females when they are larger than females. Yet, this is not an automatic consequence. The computational model DomWorld has shown that among group-living individuals, even when females are smaller than males, females may dominate some males via the winner-loser effect, and female dominance becomes greater the higher the intensity of aggression in the group. Although these predictions have been confirmed empirically in primates, including humans, they have not been tested in other taxa. Norway rats (Rattus norvegicus) are suitable to test this because they fulfill the assumptions of DomWorld: they form groups, males are larger than females, and aggression can be intense. Moreover, their intersexual dominance has seldom been studied. In the present study, we investigate whether there is dominance of females over part of the males in rats and how it emerges. We study twelve mixed-sex colonies, housed in a semi-natural environment. We show that females were dominant over on average 55% of the males even though males occupied the alpha position in all colonies but one. Moreover, as expected by DomWorld, (i) females were dominant over more males when (a) the aggression of the colony was more intense and when (b) dominants spent more time in the open arena in colonies with intense aggression, and (ii) the spatial segregation of the dominants did not depend on the intensity of aggression. In sum, we show that although females are smaller, they dominate part of the males probably through the winner-loser effect. It is of great interest to investigate these patterns in other taxa with male-biased sexual dimorphism and intense aggression.
|Evenementstitel||European Conference on Behavioural Biology 2022: All of life is social!|
|Locatie||Groningen, NetherlandsToon op kaart|
|Mate van erkenning||International|