Neoproterozoic origin and multiple transitions to macroscopic growth in green seaweeds

Andrea Del Cortona, Christopher J. Jackson, François Bucchini, Michiel Van Bel, Sofie D’hondt, Pavel Skaloud, Charles F. Delwiche, Andrew H. Knoll, John A. Raven, Heroen Verbruggen, Klaas Vandepoele, Olivier De Clerck, Frederik Leliaert

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The Neoproterozoic Era records the transition from a largely bacterial to a predominantly eukaryotic phototrophic world, creating the foundation for the complex benthic ecosystems that have sustained Metazoa from the Ediacaran Period onward. This study focuses on the evolutionary origins of green seaweeds, which play an important ecological role in the benthos of modern sunlit oceans and likely played a crucial part in the evolution of early animals by structuring benthic habitats and providing novel niches. By applying a phylogenomic approach, we resolve deep relationships of the core Chlorophyta (Ulvophyceae or green seaweeds, and freshwater or terrestrial Chlorophyceae and Trebouxiophyceae) and unveil a rapid radiation of Chlorophyceae and the principal lineages of the Ulvophyceae late in the Neoproterozoic Era. Our time-calibrated tree points to an origin and early diversification of green seaweeds in the late Tonian and Cryogenian periods, an interval marked by two global glaciations with strong consequent changes in the amount of available marine benthic habitat. We hypothesize that unicellular and simple multicellular ancestors of green seaweeds survived these extreme climate events in isolated refugia, and diversified in benthic environments that became increasingly available as ice retreated. An increased supply of nutrients and biotic interactions, such as grazing pressure, likely triggered the independent evolution of macroscopic growth via different strategies, including true multicellularity, and multiple types of giant-celled forms.

Original languageEnglish
Pages (from-to)2551-2559
Number of pages9
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number5
DOIs
Publication statusPublished - 4 Feb 2020

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