Genetic and demographic data reveal dispersal processes: Informed, massive and infrequent emigration events in Emperor penguins

Dispersal is an ubiquitous phenomenon which affects the population dynamics and evolution of natural populations, hence it is a fundamental process in driving biodiversity responses to rapid global change. However, dispersal rates and dispersal range are difficult to measure in most species, and remain unknown for many.In addition, informed behaviors, whereby individuals leave their natal area and select a breeding habitat non-randomly, may play an important role in species' responses to global change, and are even more difficult to comprehend. Here, we develop a new mathematical function combining demographic and genetic data to determine the dispersal distance, emigration rates and dispersal behaviors (random or informed emigration and establishment). We apply our approach to the Emperor penguin, a species threatened by climate change.We found that Emperor penguins have a short distance of dispersal compared to their capacity to cover large distances during migration. On average, emigration rates are small and Emperor penguins leave their colonies when the habitat becomes unsuitable (informed emigration). However, for some regions, massive emigration events can occur. Specifically, emigration is more likely to occur for habitat with low food availability that can not sustain large populations. Our model opens the doors to estimate both the mean dispersal distance, emigration rates, and dispersal behaviours across the tree of life to transform our understanding of dispersal processes and their consequences for populations and ecosystems