Communal nesting in the garden dormouse (Eliomys quercinus)

The ecology and evolution of the monito del monte, a relict species from the southern South America temperate forests

The arboreal marsupial monito del monte (genus Dromiciops, with two recognized species) is a paradigmatic mammal. It is the sole living representative of the order Microbiotheria, the ancestor lineage of Australian marsupials. Also, this marsupial is the unique frugivorous mammal in the temperate rainforest, being the main seed disperser of several endemic plants of this ecosystem, thus acting as keystone species. Dromiciops is also one of the few hibernating mammals in South America, spending half of the year in a physiological dormancy where metabolism is reduced to 10% of normal levels. This capacity to reduce energy expenditure in winter contrasts with the enormous energy turnover rate they experience in spring and summer. The unique life history strategies of this living Microbiotheria, characterized by an alternation of life in the slow and fast lanes, putatively represent ancestral traits that permitted these cold-adapted mammals to survive in this environment. Here, we describe the ecological role of this emblematic marsupial, summarizing the ecophysiology of hibernation and sociality, updated phylogeographic relationships, reproductive cycle, trophic relationships, mutualisms, conservation, and threats. This marsupial shows high densities, despite presenting slow reproductive rates, a paradox explained by the unique characteristics of its three-dimensional habitat. We finally suggest immediate actions to protect these species that may be threatened in the near future due to habitat destruction and climate change.

Patterns of nest box sharing in woodland dormice (Graphiurus murinus): Evidence for intra-sexual tolerance and communal nesting

Nest sharing in rodents and other vertebrates is believed to be promoted by the gain of thermoregulatory advantages, reproductive imperatives or to be a by-product of other benefits to group living. Here, we studied the patterns of nest box sharing over a yearly cycle in a wild population of the arboreal, nocturnal and heterothermic woodland dormouse (Graphiurus murinus). We evaluated whether the timing of dormouse aggregations and group composition were compatible with thermoregulatory or reproductive imperatives. Nest box sharing between two or more dormice was observed throughout the year and was not correlated with monthly minimum temperatures. Therefore, the observed aggregations could not be exclusively related to the gain of a thermoregulatory advantage. All-male and all-female aggregations were more frequent during the mating season, following which some females seemed to engage in communal nesting and continued to share nests with some of their offspring well beyond the weaning period. Our data suggest that nest sharing was only partly affected by basic reproductive needs. We hypothesize that dormouse aggregations were ultimately favoured by a high level of intra-sexual tolerance elicited by the presence of numerous kin-related and familiar individuals in the population. This seems to stem from the high inter-individual spatial overlaps and the promiscuous mating system previously reported in this species. Further studies focusing on natural resting sites and genetic relatedness between individuals are needed to confirm our findings and test our hypothesis.