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Updated: Jan 13, 2026

A System for Tracking the Dynamics of Social Preference Behavior in Small Rodents
Published on: November 21, 2019
Rats show qualitative sex differences in interaction preferences among unfamiliar same-sex conspecifics
Yuki Ippongi1, Yasushi Kiyokawa1, Yukari Takeuchi1
1Laboratory of Veterinary Ethology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Abstract:
In social animals, behaviors toward conspecifics are influenced by group information of other individuals. One component of group information in rats is their strains. Our previous study suggests that rats can change their social interactions depending on the strain of unfamiliar same-sex individuals. In a 60-min preference test using a three-chamber apparatus, we observed that the male Wistar subjects interacted more with Wistar and Sprague-Dawley (SD) rats than with Fischer344 (F344) rats. In contrast, the subjects showed similar levels of interaction with Wistar and SD rats. Examination of the genealogy of these strains revealed that the SD strain was established from the Wistar strain, whereas the F344 strain was established independently from the Wistar strain. Therefore, male Wistar rats appear to prefer interacting with unfamiliar rats with greater genetic similarity. Here, we assessed whether female rats also prefer to interact with strains with greater genetic similarity. In Experiment 1, unlike the male subjects, the female Wistar subjects interacted more with F344 rats than with Wistar rats. In Experiment 2, whereas the female Wistar subjects interacted more with SD rats than with Wistar rats, they showed similar levels of interaction with SD and F344 rats. Experiment 3 confirmed that these results were not due to an aversion to Wistar rats. Based on these results, we conclude that rats exhibit qualitative sex differences in their interactions with unfamiliar same-sex individuals. Whereas male rats prefer to interact with strains with greater genetic similarity, female rats prioritize strains with greater novelty.
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