• Personality dimensions and their behavioral correlates in wild virunga mountain gorillas (Gorilla beringei beringei)

      Eckardt, Winnie; Steklis, Dieter H.; Steklis, Netzin G.; Fletcher, Alison W.; Stoinski, Tara S.; Weiss, Alexander; University of Chester & The Dian Fossey Gorilla Fund International ; University of Arizona ; University of Arizona ; University of Chester ; Zoo Atlanta & The Dian Fossey Gorilla Fund International ; University of Edinburgh & Scottish Primate Research Group. (Americal Psychological Association, 2014-12-22)
      Studies of animal personality improve our understanding of individual variation in measures of life-history and fitness, such as health and reproductive success. Using a 54 trait personality questionnaire developed for studying great apes and other nonhuman primates, we obtained ratings on 116 wild mountain gorillas (Gorilla beringei beringei) monitored by the Dian Fossey Gorilla Fund’s Karisoke Research Center in Rwanda. There were eight raters who each had more than 1.5 years of working experience with the subjects. Principal component analyses identified four personality dimensions with high inter-rater reliabilities --- Dominance, Openness, Sociability, and Proto-Agreeableness --- that reflected personality features unique to gorillas and personality features shared with other hominoids. We next examined the associations of these dimensions with independently collected behavioral measures derived from long-term records. Predicted correlations were found between the personality dimensions and corresponding behaviors. For example, Dominance, Openness, Sociability, and Proto-Agreeableness were related to gorilla dominance strength, time spent playing, rates of approaches and rates of interventions in intra-group conflicts, respectively. These findings enrich the comparative-evolutionary study of personality and provide insights into how species differences in personality are related to ecology, social systems, and life history.
    • Personality in the cockroach Diploptera punctata: Evidence for stability across developmental stages despite age effects on boldness

      Stanley, Christina R.; Mettke-Hofmann, Claudia; Preziosi, Richard F.; University of Chester; University of Manchester; Liverpool John Moores University; Manchester Metropolitan University (PLOS, 2017-05-10)
      Despite a recent surge in the popularity of animal personality studies and their wide-ranging associations with various aspects of behavioural ecology, our understanding of the development of personality over ontogeny remains poorly understood. Stability over time is a central tenet of personality; ecological pressures experienced by an individual at different life stages may, however, vary considerably, which may have a significant effect on behavioural traits. Invertebrates often go through numerous discrete developmental stages and therefore provide a useful model for such research. Here we test for both differential consistency and age effects upon behavioural traits in the gregarious cockroach Diploptera punctata by testing the same behavioural traits in both juveniles and adults. In our sample, we find consistency in boldness, exploration and sociality within adults whilst only boldness was consistent in juveniles. Both boldness and exploration measures, representative of risk-taking behaviour, show significant consistency across discrete juvenile and adult stages. Age effects are, however, apparent in our data; juveniles are significantly bolder than adults, most likely due to differences in the ecological requirements of these life stages. Size also affects risk-taking behaviour since smaller adults are both bolder and more highly explorative. Whilst a behavioural syndrome linking boldness and exploration is evident in nymphs, this disappears by the adult stage, where links between other behavioural traits become apparent. Our results therefore indicate that differential consistency in personality can be maintained across life stages despite age effects on its magnitude, with links between some personality traits changing over ontogeny, demonstrating plasticity in behavioural syndromes.