22.4 Saturday, Jan. 4 14:15 Maternal effects of stress in a plural-breeding rodent BAUER, C.M.*; EBENSPERGER, L.A.; HAYES, L.D.; ROMERO, L.M.; Tufts University, Medford, MA; Pontificia Universidad Católica de Chile; University of Tennessee at Chattanooga; Tufts University, Medford, MA firstname.lastname@example.org
The quality of parental care has significant impacts on offspring fitness. In laboratory rodents, chronically stressed mothers have shorter nest bouts and spend less time licking and grooming pups, resulting in pups with hyperactive stress responses. These hyperactive stress responses are characterized by high cortisol (CORT) levels in response to stressors plus poor negative feedback, which can ultimately lead to decreased reproductive output and survival. In degus (Octodon degus) and other plural-breeding rodents that practice communal care, however, maternal care from multiple females may increase the fitness of pups born to less parental mothers. We used wild degus to test the hypothesis that plural breeding with communal care buffers post-natal stress. We used radiotelemetry to determine social group membership, and directly after parturition assigned each social group to one of three treatments: CORT, Mixed, or Control. In CORT groups, all females were implanted with cortisol pellets, while 50% and 0% of females were implanted in Mixed and Control groups, respectively. When pups emerged from burrows at four weeks of age, we sampled them for baseline and stress-induced CORT, and in addition assessed their negative feedback efficacy via a dexamethasone suppression test. CORT and Mixed pups were older at emergence and had weaker negative feedback compared to Control pups. Contrary to expectations, stress-induced CORT did not differ between treatment groups and CORT pups had lower baseline CORT compared to Control and Mixed pups. These data suggest that maternal stress impacts some aspects of the pup stress response, but that unstressed mothers may be able to mitigate some of these effects.