Affiliation, Aggression, and Selectivity of Peer Relationships in Meadow and Prairie Voles

Abstract

Relationships between adult peers are central to the structure of social groups. In some species, selective preferences for specific peers provide a foundation for consistent group composition. These preferences may be shaped by affiliation toward familiar individuals, and/or by aversion to unfamiliar individuals. We compared peer interactions in two vole species that form selective preferences for familiar same-sex individuals but differ in mating system. Prairie voles (Microtus ochrogaster) form pair bonds with mates and may reside in family groups. Meadow voles (Microtus pennsylvanicus) are promiscuous breeders that form communal winter groups in the wild, and exhibit greater social behavior in short day (SD) lengths in the laboratory. We characterized affiliative, anxiety-like, and aggressive interactions with familiar and novel same-sex conspecifics in meadow and prairie voles housed in summer- or winter-like photoperiods. Species differences in affective behaviors were pronounced, with prairie voles exhibiting more aggressive behavior and less anxiety-like behavior relative to meadow voles. Meadow voles housed in short (vs. long) day lengths were more affiliative and more interactive with strangers; prosocial behavior was also facilitated by a history of social housing. Prairie voles exhibited partner preferences regardless of sex or day length, indicating that selective peer preferences are the norm in prairie voles. Prairie vole females formed preferences for new same-sex social partners following re-pairing; males were often aggressive upon re-pairing. These data suggest that preferences for familiar peers in prairie voles are maintained in part by aggression toward unfamiliar individuals, as in mate partnerships. In contrast, social tolerance is an important feature of meadow vole peer affiliation, demonstrated by low aggression toward unfamiliar conspecifics, and consistent with field data on winter tolerance.

Multiple dimensions of social motivation in adult female degus

“…Female degus are also known to share burrows with multiple, often genetically unrelated peers [25][26][27]29,30,32,40] (in some cases even cohabitating with unrelated species [40]). As a point of contrast, prairie voles reside with only familiar pair mates or family members [41] and tend to great strangers aggressively [42]. When the two species were directly compared using a partner preference test, prairie voles have been found to spend almost all of their time near or huddling with a familiar partner [43], while degus spend their time near and huddling with partners and strangers, exhibiting no average preference for either [24].…”

“…Female degus are also known to share burrows with multiple, often genetically unrelated peers [25][26][27]30,31,33,48] (in some cases even cohabitating with unrelated species [48]). As a point of contrast, prairie voles reside with only familiar pair mates or family members [49] and tend to great strangers aggressively [50].…”

Frank Beach award winner: Neuroendocrinology of group living

“…In social interaction tests of female meadow voles across day lengths, we found that SD-housed females interacted with novel conspecifics more than LD housed females, including both affiliative social contact and aggressive interactions (Lee et al, 2017). Increased social interaction between voles in winter may be further facilitated by social experience, as pair-housed SD meadow voles sniff, groom, and huddle with novel conspecifics more than individually-housed meadow voles (see 2.2.6).…”

“…Congruent with these findings, SD meadow vole females are more active in an open field, and spend more time in the center than do LD females (Reitz, 2014). Time spent investigating a novel conspecific in the social interaction test is classically used as a measure of anxiety (File and Seth, 2003), and SD meadow vole females are more interactive than LD females in this test (Lee et al, 2017).…”

“…In addition to the physical environment, social history strongly impacts social behavior towards unfamiliar individuals: in 10 minute tests of social interaction with strangers in a neutral arena, female meadow voles housed alone exhibited more aggression and less affiliative social contact than pair-housed voles (Lee et al, 2017). Many important effects of social environment variables including weaning age, litter size, and extent of maternal care have been documented on later social behavior in voles and other rodents (e.g.…”