Artificial Selection on Relative Brain Size Reveals a Positive Genetic Correlation Between Brain Size and Proactive Personality in the Guppy

Abstract

Animal personalities range from individuals that are shy, cautious, and easily stressed (a “reactive” personality type) to individuals that are bold, innovative, and quick to learn novel tasks, but also prone to routine formation (a “proactive” personality type). Although personality differences should have important consequences for fitness, their underlying mechanisms remain poorly understood. Here, we investigated how genetic variation in brain size affects personality. We put selection lines of large- and small-brained guppies (Poecilia reticulata), with known differences in cognitive ability, through three standard personality assays. First, we found that large-brained animals were faster to habituate to, and more exploratory in, open field tests. Large-brained females were also bolder. Second, large-brained animals excreted less cortisol in a stressful situation (confinement). Third, large-brained animals were slower to feed from a novel food source, which we interpret as being caused by reduced behavioral flexibility rather than lack of innovation in the large-brained lines. Overall, the results point toward a more proactive personality type in large-brained animals. Thus, this study provides the first experimental evidence linking brain size and personality, an interaction that may affect important fitness-related aspects of ecology such as dispersal and niche exploration.

Cue-based and algorithmic learning in common carp: A possible link to stress coping style

“…RuizGomez de Lourdes et al, 2011 and see review by Korte et al, 2005). Approaching the same subject from a different angle, Kotrchal et al (2014) compared stress responsiveness in guppies (Poecilia reticulata) selected for large or small brain size. Compared to smallbrained fish, larger brained animals secreted less cortisol when stressed and were faster to explore novel environment, both traits typical of proactive animals; they were also slower to feed from novel source, showing less flexibility, again often typical of proactive animals.…”

Brain size predicts behavioural plasticity in guppies (Poecilia reticulata): An experiment

“…Such phenotypic correlations are common (Garamszegi et al., ). However, since general movement activity and risk‐taking are functionally different traits, we analysed them separately (Kotrschal, Lievens, et al., ).…”

Predator-driven brain size evolution in natural populations of Trinidadian killifish ( Rivulus hartii )

“…This work revealed rapid shifts in brain size in response to directional selection; brain size increased by 10% after two generations of selection. Increased brain size was associated with increased cognitive ability [23 -25], shifts in personality and anti-predator behaviour [26,27], and decreased susceptibility to predation [28]. This leads to the hypothesis that variation in rates of predation may be a key selective force on the evolution of brain size and that increased predation should select for increased brain size.…”