Linking differences in personality to demography in the wandering albatross

Population dynamics are shaped by individual differences. With a good
understanding of the relationships between individual differences and
vital rates, population models can be improved to yield more realistic and
detailed demographic projections. Personality is expected to shape
individual differences in performance. Yet, an empirical quantification of
its impact on population dynamics is currently lacking. Here, we developed
and analyzed a three-dimensional hyperstate population model that accounts
for three sources of individual differences simultaneously in its
structure: age, breeding state, and boldness as a measure of personality.
We parameterized our model using empirical demographic and boldness data
on the wandering albatross (Diomedea exulans) population from Crozet. We
quantified the relative importance of boldness through sensitivity
analyses and simulations of increased strength of the relationship between
boldness and three vital rates (survival, breeding probability, and
breeding success). We showed that the sensitivity of population growth
rate to changes in vital rates followed the normal distribution of
boldness within the population, with population growth rate being less
sensitive to changes in the vital rates of extreme shy or bold
individuals. Our simulations showed that increasing the strength of the
relationship between boldness and survival would yield the greatest shift
in boldness distribution over time compared to breeding probability and
breeding success. However, shifts in boldness distribution appeared
constrained by the low heritability (<0.2) value and the large
variance in boldness in this population. Our study provides an important
contribution to our understanding of the role of personality in shaping
the population dynamics of wild species. In the face of global change, our
approach offers a promising avenue to predict the potential for behavioral
adaptation. More generally, our approach may help to unravel the complex
interplay between individual variations in any (or many) traits and
population dynamics.