Demographic drivers of generation time in a bird metapopulation:
evolutionary potential and the ecological determinants of pace-of-life
- Yimen Araya-Ajoy,
- Alina Niskanen,
- Peter Ranke,
- Hannah Froy,
- Thomas Kvalnes,
- Bernt Rønning,
- Michael Pedersen,
- Thor-Harald Ringsby,
- Henrik Jensen,
- Bernt-Erik Sæther,
- Jonathan Wright
Peter Ranke
Norwegian University of Science and Technology
Author ProfileHannah Froy
Norwegian University of Science and Technology
Author ProfileThomas Kvalnes
Norwegian University of Science and Technology
Author ProfileBernt Rønning
Norwegian University of Science and Technology
Author ProfileMichael Pedersen
Norwegian University of Science and Technology
Author ProfileThor-Harald Ringsby
Norwegian University of Science and Technology
Author ProfileHenrik Jensen
Norwegian University of Science and Technology
Author ProfileAbstract
Generation time determines the pace of key demographic and evolutionary
processes. Quantified as the weighted mean age at reproduction, it can
be studied as a trait that may evolve and change in response to
ecological conditions. We combined quantitative genetic analyses of
individual projection matrices with age- and density-dependent models to
study generation time variation in a bird metapopulation. We found that
males have longer generation times than females and that it is a
heritable trait. Individuals with longer generation times contributed to
population growth later in life, lived longer, produced fewer recruits
per year, had greater lifetime reproductive success, but not necessarily
a higher expected individual growth rate. As predicted by
density-dependence theory, generation times were shorter when
populations were growing, and longer when populations were closer to
equilibrium or declining. These results support classic theory
predicting that competitive regimes are key determinants of the pace of
life-history strategies.