Amphithéâtre Marguerite de Navarre, Site Marcelin Berthelot
Open to all
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Abstract

Today's major environmental issues are energy, water, climate change and biodiversity.

Biodiversity was born in the ancestral ocean, built on pre-biotic chemistry derived from earlier geo-diversity, around 3850 million years ago (Ma), when the first cells cloned by scissiparity. Life then diversified in the ocean over billions and hundreds of millions of years, and essential events took place: the emergence of the eukaryotic cell, the capture of bacteria that would become organelles through symbiosis (mitochondria and plastids), multicellularity and, finally, the development of sexuality. Everything was in place when organized metazoan life emerged from the oceans around 450 Ma. Biodiversity (arthropods) exploded on the continents in the Carboniferous forests and spread everywhere, with species organizing themselves into populations, ecosystems, biomes... Since 570 Ma, some sixty "extinction crises" have been recorded, including five particularly significant ones, the most acute of which took place around 251 Ma, between Permian and Triassic (Paleozoic/Mesozoic hinge), during which 96% of the major species became extinct.