The Latitudinal Diversity Gradient of Brachiopods over the Past 530 Million Years

The origin of the latitudinal diversity gradient remains one of the most significant, unresolved challenges in macroecology, yet it has received relatively little attention from paleontologists. A new database of brachiopod genus occurrences in space and time has been used to reconstruct the latitudinal diversity gradient from 530 million years ago to the present day in 10‐million‐year increments. A latitudinal diversity gradient has persisted continuously through time. Notably, peak diversity did not usually occur at or near the equator but drifted northward through time, beginning in southern midlatitudes in the early Paleozoic Era and culminating in northern midlatitudes today. This pattern remains even after various corrections for sampling bias. The shift in peak diversity closely parallels a concomitant shift in the latitudinal distribution of continental shelf area, suggesting that shelf area has exerted a strong control of first‐order spatial patterns of brachiopod diversity. The steepness of the gradient was controlled by the rise and fall of peak diversity, which was temporally more variable than diversity at higher latitudes. These results demonstrate the continuous presence of a latitudinal diversity gradient of brachiopod genera through most of the Phanerozoic, despite major changes in the global diversity and ecological dominance of the brachiopods.