EARTH-LIFE TRANSITIONS, ORGANISMAL-ENVIRONMENTAL INTERACTIONS, AND THE KEY ROLE OF FUNCTIONAL TRAITS (Invited Presentation)

From the Proterozoic explosion of eukaryotic life to the bewildering tangle of Anthropocene extinction, transitions in Earth systems and our planet’s biota are closely tied. The geological and paleontological records preserve the history of major transitions in life, providing crucial yet still poorly understood data about how their interactions affect the balance of background or mass extinctions, of explosions or declines in biodiversity, and of gradational change or tipping points. Among the great challenges for generalizing processes involved in Earth-life transitions is that the functional properties of organisms are malleable. The interactions between organisms and their larger environments are mediated by traits, whether those be the metabolic pathways needed to process oxygen or the tooth structures needed to process newly evolved seed types. Functional traits such as these not only provide the basis for understanding how Earth-life transitions play out, but the biological side of the trait-environment interaction evolves in a more complex way than does the physical environmental side. A synthesis of Earth system processes, functional trait biology, and evolution are critical for improving our understanding of Earth-life transitions. Here we show how new ecometric methods – ones that use traits rather than taxa as data – can be used to refocus research onto the processes by which biological and Earth systems interact. Using a combination of Neogene mammalian carnivores and computational modelling, we show that trait turnover and clade turnover can be decomposed into two different processes that are linked only under some circumstances. Using this example, we explore some of the factors that tip the balance between evolution and extinction and thus the processes that underpin biotic change on our planet.