LAUSR

Change begets change In the Anthropocene, humans are altering ecosystems, causing extinctions, and reassorting species distributions. As we facilitate these changes, we are creating new collections of species. Such “novel communities” are not specific to our epoch, and the patterns of diversity and extinction associated with past events can shed light on the implications of current community restructuring. Pandolfi et al. looked at marine plankton communities over the past ∼66 million years and found that the emergence of novel communities leads to further novelty and extinction (see the Perspective by Dornelas and Madin). Although community change is a natural biological response to environmental change, the current rate of change could lead to impending and rapid impacts. Science, this issue p. 220; see also p. 164 Novelty begets novelty, and extinction, in plankton communities. Environmental change is transforming ecological assemblages into new configurations, resulting in novel communities. We developed a robust methodology to detect novel communities, examine patterns of emergence, and quantify probabilities of local demographic turnover in transitions to and from novel communities. Using a global dataset of Cenozoic marine plankton communities, we found that the probability of local extinction, origination, and emigration during transitions to a novel community increased two to four times that of background community changes. Although rare, novel communities were five times more likely than chance to shift into another novel state. For marine plankton communities at a 100,000-year time grain, novel communities were sensitive to further extinctions and substantial community change.