The sound of fear is heritable

Abstract The nonlinearity and fear hypothesis predicts that highly aroused vocal mammals and birds produce vocalizations (notably alarm calls and screams) which contain a variety of non-linear phenomena (NLP). Such vocalizations often sound ‘noisy’ because vocal production systems are over-blown when animals are highly aroused. While much is known about the conditions under which animals produce vocalizations containing NLP, and how species respond to them, there is little research about the heritability of such behavioral traits. Using the quantitative genetic animal model, we estimated the genetic basis of ‘noise’ in alarm calls produced by females and found significant heritability in call entropy—our measure of the noisiness. About 9% of variance in noisiness can be accounted for by genetic differences. Taken together, these findings suggest that the degree to which marmots produce noisy calls is modestly heritable and can be thus subject to further evolution via natural selection.