Macroevolutionary perspectives on Anthropocene extinction

Abstract

A great deal of macroevolutionary research on extinction has focused on large-scale processes, particularly mass episodes. In contrast, many recent conservation studies focus on Anthropocene dynamics at the population level. We discuss three ways in which a synthesis between these perspectives might illuminate hidden assumptions of value and reveal promising agendas for conservation biology. First, some lineages may have been on extinction trajectories before global change commenced. While it may be difficult to quantify this directly, the potential for pre-existing net-negative diversification rates in lineages or terminal declines in species may have a strong impact on our ethical valuations of biodiversity and consequent management decisions. Second, it is worthwhile to quantify the shape and scale of the Sixth Extinction relative to previous mass extinctions and we outline and model several relevant parameters, including the initial magnitude and subsequent change in diversification rates contributing to recovery. Placing recent estimates of Anthropocene extinction rates into a historical macroevolutionary context may suggest more precise frameworks for interpreting and extrapolating present-day patterns. Third, focusing on recovery dynamics from previous mass extinctions may be valuable, as quantitative models of present-day extinction portend various scenarios for future re-diversification. In this context, “conservation” is less about preserving past or existing states, but rather creating and promoting novel starting points for the near-term function and future evolution of biodiversity, differing from pre-human trajectories. Integrating historical and present-day perspectives on extinction promises a synergistic research program holding potential insights for macroevolution, conservation, and environmental ethics.