Pup growth rates and breeding female weight changes in two populations of captive bred degus (Octodon degus), a precocial caviomorph rodent.

Caviomorph rodents are renowned for comparatively long gestations and producing relatively precocious offspring. The degu (Octodon degus) is one such caviomorph, originating in central Chile and providing communal pup care within wild groups. Reported are pup growth data for two populations of captive bred degus in Britain and Chile (representing wild populations), for the first time analysing pup development over the postpartum and weaning period in detail. Pups in both colonies were found to be similarly precocial at birth as assessed by open eyes and presence of full body hair. Degu pups in the British colonies put on weight at a rate of 2-3 g/day, while pups in the Chilean colonies put on weight at a rate of 1-2 g/day over the first 14 days. At birth, individual neonates weighed 5 ± 1% of maternal mass for the British sample and 6 ± 0.5% for the Chilean sample. Sexual dimorphism occurred in the weight and growth rates of pups in both samples, despite the lack of sexual dimorphism in adults of the species. Data for breeding female weight changes were also analysed, providing the first reported observations for this crucial period. Pregnant female weight gain was found to vary over the course of gestation, and post partum weight changes varied significantly between breeding females in accordance with litter size.

Isolation and characterization of polymorphic microsatellite loci from Octodon degus.

Quantifying genetic kinship and parentage is critical to understanding the adaptive consequences of sociality. To measure fitness in a species with variable group structure, we isolated 14 microsatellite loci from Octodon degus, a semi-fossorial rodent endemic to Chile. The number of alleles per locus ranged from four to 14. Thirteen loci were in Hardy-Weinberg proportions, with values of observed heterozygosity ranging from 0.550 to 0.950. These markers provide the basis for future studies of the direct fitness consequences of sociality in O. degus.