Experimental evolution of personality traits: open-field exploration in bank voles from a multidirectional selection experiment

Abstract

Evolution of complex physiological adaptations could be driven by natural selection acting on behavioral traits. Consequently, animal personality traits and their correlation with physiological traits have become an engaging research area. Here, we applied a unique experimental evolution model-lines of bank voles selected for (A) high exercise-induced aerobic metabolism, (H) ability to cope with low-quality herbivorous diet, and (P) intensity of predatory behavior, that is, traits shaping evolutionary path and diversity of mammals-and asked how the selection affected the voles' personality traits, assessed in an open field test. The A- and P-line voles were more active, whereas the H-line voles were less active, compared those from unselected control lines (C). H-line voles moved slower but on more meandering trajectories, which indicated a more thorough exploration, whereas the A- and P-line voles moved faster and on straighter trajectories. A-line voles showed also an increased escape propensity, whereas P-line voles tended to be bolder. The remarkable correlated responses to the selection indicate a common genetic underlying mechanism of behavioral and physiological traits, and support the paradigm of evolutionary physiology built around the concept of correlated evolution of behavior and physiology.

Keywords: Myodes glareolus; behavior; evolution; physiology; rodents; selection.

Figure 1.

(A–K) Adjusted least-square means from Mixed ANCOVA models (±95% confidence intervals) of behavioral traits measured in in Open Field test in bank voles from the selection experiment (C: unselected control, A: “aerobic”, H: “herbivorous”, P: “predatory”). Variables that were transformed for the analysis has been back transformed to produce results in original unit. The traits are: (A) Total distance (m), (B) Proportion of time spent moving, (C) Maximum velocity (cm/s), (D) Average velocity (cm/s), (E) Meandering coefficient (rad/cm), (F) Frequency of returns from the edge to central zone (only for individuals that reached the edge zone), (G) Proportion of time spent in the edge zone, (H) Proportion of distance covered in the edge zone, (I) Frequency of wall-seeking behavior (thigmotaxis), (J) Proportion of time spent in the central zone (only following returns), (K) Proportion of distance covered in the central zone (only following returns). (L) coefficients of the Weibull model for the latency to reach the edge zone at the onset of the open field test (“shape” describes the mean latency; “scale” describes variance of the latency).