From The Economist:
Since the early 1970s, the two grandest patterns of life—how species are arranged in space and how they are arranged in time—have divided their opposing camps quite neatly. Those who squabble over space disagree about why there are more species in the tropics than anywhere else. To them, the tropics are either where species are more often born (cradles of diversity) or where they tend not to die (museums of diversity). By contrast, biologists concerned with patterns in time tenaciously debate whether new species come into being in a smooth and gradual manner, or whether the history of life is actually a series of bursts of change that are interspersed with periods when nothing much happens.
Two papers just published in Science have cast light on these questions, and their findings, if not necessarily resulting in compromise, do show the value of taking leaves out of other people’s books. The “space biologists” have looked into time, namely the fossil record over the past 11m years. Meanwhile the “time biologists” have looked at the here and now and found evidence in living species for periods of rapid evolution in their genes.