BIRDCLIMCHANGE · Timing of bird migration under climate change: phenotypic plasticity, microevolutionary response or both?

Climate is changing at a global scale, exposing organisms to novel environmental conditions and potentially having a profound impact on life-history traits of individuals, and, hence, on the ecology, distribution and persistence of species. Among the most apparent effects of climate change are alterations in the phenology of many species as a result of changes in the timing of seasons. One of the most striking examples concerns the life-cycle of migratory birds: during recent decades a growing number of studies have reported a direct relationship between climate change and bird migration phenology, essentially showing that birds arrive earlier to their breeding grounds in the Northern Hemisphere, in accordance with a trend towards higher global temperature. However, the ultimate mechanisms by which these phenotypical adaptations occur are poorly understood. Two contrasting, non-exclusive, mechanisms may account for the observed responses: a microevolutionary response to selection and/or phenotypic plasticity. To explore which of these mechanisms operates and when, here we propose the combined use of long-term datasets of individually-marked migratory birds, their phenotypic and life-history traits and their fitness parameters, along with climatic data and pedigree information. We propose to identify which phenotypic traits have changed over time because of the influence of climate change, by using a range of statistical analyses and mathematical modelling (capture-mark-recapture methods, linear mixed modelling). Then, we propose to study the inheritance patterns of the most-influenced phenotypic traits using pedigree information and quantitative genetics methods (“animal models”). This combined use of ecology and evolution methodologies through heredity studies of pedigrees aims to help understand how the adaptive mechanisms to climate change take place in the particular case of bird migration.