Fig. 2
Photoperiod-induced alterations in behaviors, body mass, food intake, and reproductive phenotypes of Brandt’s voles. a, b Relative average activity time of voles in 24 h by the end of photoperiod experiment. c, d Number of attacks and attack duration at week 2, week 4, week 6, and week 8. e, f Changes in food intake and body mass during the period of photoperiod acclimation. g Effect size (i.e., Cohen’s D) of photoperiod manipulation on reproductive hormones or genes expression. Cohen’s D = (MeanLD–MeanSD)/pooled standard deviations for the two groups. TWW, testicular wet weight; TWW/BM, the ratio of testicular wet weight to body mass; EWW, epididymis wet weight; EWW/BM, the ratio of epididymis wet weight to body mass. *P < 0.05, **P < 0.01, and ***P < 0.001