Communal nesting and kinship in degus (Octodon degus)

Abstract

Communal nesting is a fundamental component of many animal societies. Because the fitness consequences of this behavior vary with the relatedness among nest mates, understanding the kin structure of communally nesting groups is critical to understanding why such groups form. Observations of captive degus (Octodon degus) indicate that multiple females nest together, even when supplied with several nest boxes. To determine whether free-living degus also engage in communal nesting, we used radiotelemetry to monitor spatial relationships among adult females in a population of O. degus in central Chile. These analyses revealed that females formed stable associations of > 2-4 individuals, all of whom shared the same nest site at night. During the daytime, spatial overlap and frequency of social interactions were greatest among co-nesting females, suggesting that nesting associations represent distinct social units. To assess kinship among co-nesting females, we examined genotypic variation in our study animals at six microsatellite loci. These analyses indicated that mean pairwise relatedness among members of a nesting association (r=0.25) was significantly greater than that among randomly selected females (r=-0.03). Thus, communally nesting groups of degus are composed of female kin, making it possible for indirect as well as direct fitness benefits to contribute to sociality in this species.

The flexible clock: predictive and reactive homeostasis, energy balance and the circadian regulation of sleep–wake timing

“…Some rodent species that are diurnal in the field become nocturnal under certain laboratory conditions, including degus (Ebensperger et al, 2004;Kas and Edgar, 1999), hamsters (Gattermann et al, 2008), tuco-tucos (Tomotani et al, 2012), cururos (Urrejola et al, 2005), Nile grass rats (Blanchong et al, 1999) and golden spiny mice (Cohen et al, 2010). These discrepancies in circadian rhythms between the laboratory and field raise the question of whether a 'default' circadian phenotype actually exists.…”

Effects of Habitat and Social Complexity on Brain Size, Brain Asymmetry and Dentate Gyrus Morphology in Two Octodontid Rodents

“…degus live in relatively large groups ranging from 1 to 12 adult individuals , and females of this species exhibit communal care of offspring [Ebensperger et al, 2004]. These characteristics have been documented in at least four populations of this species [Ebensperger et al, 2004[Ebensperger et al, , 2012Jesseau, 2004;Sobrero et al, unpubl. data], implying a high frequency of social interactions and probably a need for cognitive skills underlying these interactions.…”

“…The original research reported herein was performed under guidelines established by the Pontificia Universidad Católica de Chile Bioethical Committee (CBB-042/2011) and adhered to Chilean laws [permits 1-154.2010 (7989), 1-109.2011 (6749), 1-90.2011 (4731) and 1-95-2012 (4486) [Ebensperger et al, 2004[Ebensperger et al, , 2012, we placed traps near burrow openings and inside patches with high shrub cover and baited them with rolled oats, fruity cereals and sunflower seeds. During each capture, we recorded sex, body mass (to 0.1 g) and reproductive status (whether a female had a perforated vagina, was pregnant or lactating) of all degus, and each animal was marked with an ear tag (Monel 1005-1; National Band and Tag Co., Newport, Ky., USA).…”

“…Adult-aged degus were fitted with a radio collar weighing 7-9 g (RI-2D; Holohil Systems Limited, Carp, Ont., Canada; SOM-2190A, and BR radio collars; AVM Instrument Co., Colfax, Calif., USA). At the end of our study, all radio-collared animals were recaptured and radio collars were removed [Ebensperger et al, 2004[Ebensperger et al, , 2012.…”

“…Group size in turn was quantified from (i) the number of male and female adults sharing nesting sites and from (ii) the extent to which range areas of these adults overlap (a measure of social cohesion during activity). A previous study indicated that degus from the same social group (based on the sharing of nesting sites) also share their foraging areas [Ebensperger et al, 2004]. Thus, populations where a larger number of adults shared same burrow systems and showed greater spatial overlap were considered relatively more 'social' [Sobrero et al, 2014].…”