Born to lead? Heart rate in pups predicts dominance in alpine marmots (Marmota marmota)

Abstract Individuals of the same species may vary in their morphological and physiological traits, and such differences potentially influence key aspects of an individual life history such as the probability of becoming dominant. In this study, we investigated whether in Alpine marmots ( Marmota marmota ) physiological (i.e., heart rate, used as a component of personality) and morphological (i.e., body mass) traits measured early in life could predict future dominance status in the social group. We used long-term data (2006–2025) from 134 adults, including a subset of 34 individuals that were sampled as pups and subsequently recaptured as adults. We found that pups with higher heart rates (i.e., proactive individuals) had a greater probability of achieving dominance in adulthood. On the contrary, our results did not show any association between body mass in pups and dominant position in adulthood while adult body mass is positively correlated with dominance status. These findings suggest that body mass may become relevant only later in life, likely as a cause or consequence of dominance status. In conclusion, our findings highlight the importance of early-life personality traits in determining future social status, and provide empirical support for the Pace of Life Syndrome (POLS) hypothesis by confirming the fundamental importance of personality in life-history strategies.