MODE DOES NOT CORRELATE WITH TEMPO IN EVOLUTION

A paradox in evolutionary biology is the contrasting amounts of evolutionary change observed across long and short time scales. The dominating view of evolution based on the fossil record is that established species remain more or less unaltered during their existence. Such periods without any significant evolution are referred to as stasis and do not fit with the observation of high potential for evolution in contemporary populations. Investigating 394 fossil time series, I demonstrate that the non-accumulating phenotypic fluctuations during stasis travel equal distances in phenotype space compared to lineages showing directional change. Stasis therefore represents the same amount of continuous evolution as other modes in the fossil record. The appearance of stasis holds information on the persistence of adaptive zones and ecological niches through time, but is rarely an example of no evolution in the fossil record.