Archive | 2021
Detecting climate signals in populations across life histories
Abstract
Climate impacts are not always easily discerned in wild populations as\nclimate change occurs in the context of natural variability.\nFurthermore, species responses to climate change and variability differ\namong life histories. The time of emergence (ToE) identifies when the\nsignal of anthropogenic climate change can be quantitatively\ndistinguished from noise associated with natural variability. This\nconcept has been applied extensively in the climate sciences, but has\nnot yet formally been explored in the context of population dynamics.\nHere, we present a theoretical assessment of the ToE of climate-driven\nsignals in population dynamics (ToEpop) to detect climate signals in\npopulations. We identify the dependence of ToEpop on the magnitude of\nclimate trends and variability and explore the demographic controls on\nToEpop. We demonstrate that different life histories (fast species vs.\nslow species), demographic processes (survival, reproduction) and\nfunctional relationships between climate and demographic rates, yield\npopulation dynamics that filter trends and variability in climate\ndifferently. We illustrate empirically how to detect the point in time\nwhen anthropogenic signals in populations emerge from the envelope of\nnatural variability for a species threatened by climate change: the\nemperor penguin. Finally, we propose six testable hypotheses and a road\nmap for future research.