Day-length and circadian variation in groups in RFID tracked habitats

Kayla Rendon-Torres, Eckerd College, Biology Discipline

Kelley Power, University of California Berkeley, Integrative Biology Discipline

Annaliese Beery, University of California Berkeley, Integrative Biology Discipline

Meadow voles (Microtus pennsylvanicus) undergo changes in social organization in response to seasonal cues in the wild, providing a unique opportunity to study the mechanisms that support that transition. In summer, female meadow voles are territorial and nest alone, whereas in winter, females and males cohabit in groups. In the lab, manipulating photoperiod (i.e., summer-like long day lengths (LD) and winter-like short days (SD)) simulates these seasonal changes. Although meadow voles live in groups in the winter, prior studies of seasonal variation in social behavior have focused on brief, dyadic interactions. To study the effects of day length on extended social interactions in groups, we implemented an automated tracking system using radio frequency-identification (RFID) technology. In each trial, four females were tracked in a multi-chambered arena over a one-week period. Open-source software (Voletron) was developed and used to infer each vole’s locomotion, position, and co-occurrence with other voles throughout the day in the arena. Across day lengths, SD voles spent more time in groups of 2-4 than LD voles (p<0.0001), consistent with field data. Analysis of previous temperature data (Beery et al., 2008) showed SD voles exhibited a decrease in social behavior strongly correlating with an increase in core body temperature across a 24-hr period. Both SD and LD voles were also more likely to be alone as lights went off. RFID-tracked habitats can be easily adapted for studies in other small animals to improve laboratory research on group dynamics.

For more information: knrendon@eckerd.edu