Punctuated Non-Equilibrium and Niche Conservatism Explain Biodiversity Fluctuations through the Phanerozoic (Including Supplement)

1 Fluctuations in biodiversity, both large and small, are pervasive through the fos2 sil record, yet we do not understand the processes generating them. Here we use a 3 novel extension of theory from non-equilibrium statistical physics to show that three 4 universal properties of macroevolution—punctuated adaptive radiation, niche conser5 vatism and resultant heterogeneity of diversification rates between taxa—are sufficient 6 to explain the previously unaccounted for fat-tailed form of fluctuations in diversity 7 through the Phanerozoic. Using this theory, known as super-statistics, we identify taxo8 nomic orders as largely autonomous evolutionary units, each likely experiencing its own 9 unique and conserved region of an adaptive landscape. The separation of timescales 10 between background origination and extinction compared to the origin of major eco11 logical and evolutionary innovations between orders allow within-order dynamics to 12 reach equilibrium, while between-order diversification is non-equilibrial, driven by ma13 jor evolutionary innovations. Compared to other approaches that have used simple 14 birth-death processes, equilibrial dynamics or non-linear theories from complexity sci15 ence, super-statistics is superior in its ability to account for both small and extreme 16 fluctuations in fossil diversity. Its success opens up new research directions to better 17 understand the universal nature of non-equilibrium dynamics across disparate systems 18 of interest—from societal to physical to biological. Specifically in the biological case, 19 research is motivated to understand the evolutionary processes leading to the stasis 20 of order-level occupancy in an adaptive landscape punctuated by innovations between 21 orders. 22