April 12 2021: publication ScienceAdvances
Truncated bimodal latitudinal diversity gradient in early Paleozoic phytoplankton
The latitudinal diversity gradient (LDG)—the decline in species richness from the equator to the poles—is classically considered as the most pervasive macroecological pattern on Earth, but the timing of its establishment, its ubiquity in the geological past, and explanatory mechanisms remain uncertain. By combining empirical and modeling approaches, we show that the first representatives of marine phytoplankton exhibited an LDG from the beginning of the Cambrian, when most major phyla appeared. However, this LDG showed a single peak of diversity centered on the Southern Hemisphere, in contrast to the equatorial peak classically observed for most modern taxa. We find that this LDG most likely corresponds to a truncated bimodal gradient, which probably results from an uneven sediment preservation, smaller sampling effort, and/or lower initial diversity in the Northern Hemisphere. Variation of the documented LDG through time resulted primarily from fluctuations in annual sea-surface temperature and long-term climate changes.
References
Axelle Zacaï, Claude Monnet, Alexandre Pohl, Grégory Beaugrand, Gary Mullins, David M. Kroeck and Thomas Servais – Truncated bimodal latitudinal diversity gradient in early Paleozoic phytoplankton – Science Advances (2021) Vol. 7, no. 15, eabd6709 – https://doi.org/10.1126/sciadv.abd6709