Microtine rodents are an ideal genus in which to study the role of the environment on the covariation of affiliative social relationships and patterns of paternal and maternal behaviors, and to determine what neurobiological variations are responsible for these behaviors. Extensive field and laboratory data are available on a number of closely related species with different social and parental patterns of behavior. Microtus ochrogaster (prairie voles) are primarily monogamous, with pair-bonding and biparental care. In contrast, Microtus montanus (montane voles) are promiscuous breeders and males rarely share the nest of the female or care for young in the field. Intermediate between these two extremes is Microtus pennsylvanicus (meadow voles), which have a non-monogamous mating system. During the summer breeding season, males are rarely found in the nests of females or seen caring for young. However, during the colder months of the year, males are found in the field nests with the female and pre- weanling young. Successful meadow vole colonies are rare and cost only slightly more than mice to maintain. In contrast, starting a new colony from wild caught individuals is difficult, costly and time consuming. Thus, maintaining a colony for access by other researchers and to maintain our ongoing research examining variation in reproductive behaviors across closely related species is valuable and cost-effective. During a year of support, while seeking additional sources of funding, the PI will continue to test the hypothesis that photoperiod and duration of cohabitation will influence the formation of partner preferences and paternal behavior in non-monogamous meadow voles, and behaviors may be equivalent to those of monogamous prairie voles under some conditions. Dr. Lee will determine the rate of development and the extent of partner preferences demonstrated by male and female meadow voles cohabiting under winter or summer photoperiods and paternal behavior of males. By manipulating the environment (photoperiod), the PI expects to alter the amount of affiliative and paternal behavior of meadow voles and the rate at which these behaviors develop. Because males in summer conditions are aggressive towards unfamiliar animals and not prepared to live in groups, while animals in winter conditions live in groups and are not aggressive, Dr. Lee hypothesizes that full paternal care will be evident in male meadow voles housed in SD without prior exposure to pups. Alternatively, she may find no influence of photoperiod on development of affiliative behaviors or paternal behavior, indicating that seasonal changes in sociality may not correlate with altered development of these behaviors.
