23 janvier 2020 à 13h30 : déjeuner scientifique
« Phytoplankton biogeography in the early Palaeozoic: spatial distribution of diversity and control factor »
The latitudinal diversity gradient (LDG) – the decrease in species number from the equator to the poles – is considered as the most pervasive large-scale biological pattern on Earth, but the timing of its establishment, its ubiquity in the geological past and explanatory mechanisms remain uncertain. In this study, we show that acritarchs – the first representatives of marine phytoplankton in the fossil record – exhibited a LDG as early as the beginning of the Cambrian, when most major marine phyla appeared. However, this LDG was atypical, showing a single peak of diversity in the Southern and not in the Northern Hemisphere. Our findings suggest that variation of this LDG through time resulted from both annual sea-surface temperature and long-term climate fluctuations.
Salle 410, bât. B35 (3ème étage, aile nord), Université de Poitiers.