LEE, DN*; TANG-MARTINEZ, Z; University of Missouri – St. Louis; University of Missouri – St. Louis: of Early Social Environment on the Physical Development of Prairie Voles

In general, the size at birth, size at weaning, and growth rate of rodents vary with differences in the early environment a neonate experiences (Mendl 1988). This study examines the impact of sire and siblings on the physical development of prairie voles, Microtus ochrogaster. Two questions are examined. 1) How does a male parent affect the physical development of its offspring? 2) How does the presence of siblings affect the physical development of pups? Previous studies have demonstrated that there is an inverse relationship between litter size and mean pup weight at birth. Particularly, individual prairie vole pups born to larger litters tend to have lower individual weights (Solomon 1994). However, preliminary analysis of our data reveals that the presence or absence of the father affects weight at weaning, and that pups raised with siblings are lighter at weaning. Other measurements of physical development, like the age in days at which eyes open or the age at which independent movement occurs may be different for pups raised in different early social environments. Measures of physical development may have fitness consequences like the likelihood of survival.