Early Archean fossil bacteria and biofilms in hydrothermally-influenced sediments from the Barberton greenstone belt, South Africa

Westall, F.; Wit, Maarten J. de; Dann, Jesse C.; Gaast, Sjerry van der; Ronde, C. E. J. de; Gerneke, Dane

doi:10.1016/s0301-9268(00)00127-3

Cited by 310 publications

(182 citation statements)

References 45 publications

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“…As in those studies, we included uncertainty in the ages of fossils by constraining each calibration to a range rather than to a point estimate. We constrained the divergence between red algae and (green algae ϩ land plants) to a maximum of 3500 My, the age of the first known fossils (20,21). Within the red algae, we constrained the deepest divergence to the age of the oldest known red algal fossil, Bangiomorpha pubescens (1174 -1222 My) (22) and that between Gracilaria tenuistipitata and Palmaria palmata to the age of the Doushantuo Florideophyte fossils (595-603 My) (23,24).…”

Section: Methodsmentioning

confidence: 99%

Triassic origin and early radiation of multicellular volvocine algae

Herron

Hackett

Aylward

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

242

303

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Evolutionary transitions in individuality (ETIs) underlie the watershed events in the history of life on Earth, including the origins of cells, eukaryotes, plants, animals, and fungi. Each of these events constitutes an increase in the level of complexity, as groups of individuals become individuals in their own right. Among the best-studied ETIs is the origin of multicellularity in the green alga Volvox, a model system for the evolution of multicellularity and cellular differentiation. Since its divergence from unicellular ancestors, Volvox has evolved into a highly integrated multicellular organism with cellular specialization, a complex developmental program, and a high degree of coordination among cells. Remarkably, all of these changes were previously thought to have occurred in the last 50 -75 million years. Here we estimate divergence times using a multigene data set with multiple fossil calibrations and use these estimates to infer the times of developmental changes relevant to the evolution of multicellularity. Our results show that Volvox diverged from unicellular ancestors at least 200 million years ago. Two key innovations resulting from an early cycle of cooperation, conflict and conflict mediation led to a rapid integration and radiation of multicellular forms in this group. This is the only ETI for which a detailed timeline has been established, but multilevel selection theory predicts that similar changes must have occurred during other ETIs.evolution ͉ multicellularity ͉ multilevel selection ͉ transitions in individuality ͉ Volvox T he history of life on Earth has involved a number of evolutionary transitions in individuality (ETIs), in which groups of once-autonomous individuals became new individuals. Through the transfer of fitness from the individuals making up the group to the group itself, a new entity was formed with a single fitness and a single evolutionary fate. In this way, groups of interacting molecular replicators became single-celled organisms, prokaryotic cells became a primitive eukaryote, groups of single-celled organisms became multicellular organisms, and groups of multicellular organisms became social individuals (as in the social insects). In many cases such transitions have opened up entire new adaptive landscapes leading to vast radiations as completely new ways of being alive became available (e.g., cellular life, eukaryotes, plants, and animals). Understanding how and why groups of individuals become new kinds of individuals is a major challenge in explaining the history of life.The transition from unicellular to multicellular life is the paradigm case of the integration of lower-level individuals (cells) into a new higher-level individual-the multicellular organism. This transition has occurred dozens of times independently, for example in the red algae, brown algae, land plants, animals, and fungi (reviewed in ref. 1). Among the best-studied ETIs is the origin of multicellularity in the green alga Volvox and its relatives (the volvocine algae), which have been develop...

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Section: Methodsmentioning

confidence: 99%

Triassic origin and early radiation of multicellular volvocine algae

Herron

Hackett

Aylward

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

242

303

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“…O ( (Walsh & Lowe 1985;Walsh 1992) shallow marine (Walsh & Lowe 1985;Walsh 1992) diverse filaments (Walsh & Lowe 1985;Walsh 1992) shallow marine (Walsh & Lowe 1985;Walsh 1992) et al 2002) colonial coccoids (Muir & Grant 1976; shallow marine (Muir & Grant 1976;Westall et al 2001) ca 3316 (Knoll & Barghoorn 1977) shallow marine (Knoll & Barghoorn 1977)…”

Section: )mentioning

confidence: 99%

Fossil evidence of Archaean life

Schopf

2006

Phil. Trans. R. Soc. B

420

245

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Evidence for the existence of life during the Archaean segment of Earth history (more than 2500 Myr ago) is summarized. Data are presented for 48 Archaean deposits reported to contain biogenic stromatolites, for 14 such units reported to contain 40 morphotypes of putative microfossils, and for 13 especially ancient, 3200-3500 Myr old geologic units for which available organic geochemical data are also summarized. These compilations support the view that life's existence dates from more than or equal to 3500 Myr ago.

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“…The single coccoid cell colony found is a little more plausibly biogenic, but need not be cyanobacterial. Unnamed simple filamentous fossils, 1-2 µm in diameter and resembling modern gliding eubacteria such as green non-sulphur bacteria, Flexibacter or Beggiatoa, found in stromatolites about 3n4 Gy old from South Africa (Walsh & Lowe, 1985) and simple bacteria-like forms (Westall et al, 2001) are more plausibly biogenic. A meshwork of thinner pyritic filaments in a 3n25-Gy-old deep-sea volcanic sulphide deposit might be chemotrophic bacteria (Rasmussen, 2000).…”

mentioning

confidence: 99%

The neomuran origin of archaebacteria, the negibacterial root of the universal tree and bacterial megaclassification.

Cavalier‐Smith¹

2002

International Journal of Systematic and Evolutionary Microbiology

418

590

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Prokaryotes constitute a single kingdom, Bacteria, here divided into two new subkingdoms : Negibacteria, with a cell envelope of two distinct genetic membranes, and Unibacteria, comprising the new phyla Archaebacteria and Posibacteria, with only one. Other new bacterial taxa are established in a revised higher-level classification that recognizes only eight phyla and 29 classes. Morphological, palaeontological and molecular data are integrated into a unified picture of large-scale bacterial cell evolution despite occasional lateral gene transfers. Archaebacteria and eukaryotes comprise the clade neomura, with many common characters, notably obligately co-translational secretion of N-linked glycoproteins, signal recognition particle with 7S RNA and translationarrest domain, protein-spliced tRNA introns, eight-subunit chaperonin, prefoldin, core histones, small nucleolar ribonucleoproteins (snoRNPs), exosomes and similar replication, repair, transcription and translation machinery. Eubacteria (posibacteria and negibacteria) are paraphyletic, neomura having arisen from Posibacteria within the new subphylum Actinobacteria (possibly from the new class Arabobacteria, from which eukaryotic cholesterol biosynthesis probably came). Replacement of eubacterial peptidoglycan by glycoproteins and adaptation to thermophily are the keys to neomuran origins. All 19 common neomuran character suites probably arose essentially simultaneously during the radical modification of an actinobacterium. At least 11 were arguably adaptations to thermophily. Most unique archaebacterial characters (prenyl ether lipids ; flagellar shaft of glycoprotein, not flagellin ; DNA-binding protein 10b ; specially modified tRNA ; absence of Hsp90) were subsequent secondary adaptations to hyperthermophily and/or hyperacidity. The insertional origin of protein-spliced tRNA introns and an insertion in proton-pumping ATPase also support the origin of neomura from eubacteria. Molecular co-evolution between histones and DNA-handling proteins, and in novel protein initiation and secretion machineries, caused quantum evolutionary shifts in their properties in stem neomura. Proteasomes probably arose in the immediate common ancestor of neomura and Actinobacteria. Major gene losses (e.g. peptidoglycan synthesis, hsp90, secA) and genomic reduction were central to the origin of archaebacteria. Ancestral archaebacteria were probably heterotrophic, anaerobic, sulphur-dependent hyperthermoacidophiles ; methanogenesis and halophily are secondarily derived. Multiple lateral gene transfers from eubacteria helped secondary archaebacterial adaptations to mesophily and genome re-expansion. The origin from a drastically altered actinobacterium of neomura, and the immediately subsequent simultaneous origins of archaebacteria and eukaryotes, are the most extreme and important cases of T. Cavalier-Smith quantum evolution since cells began. All three strikingly exemplify De Beer's principle of mosaic evolution : the fact that, during major evolutionary transformations, some org...

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Early Archean fossil bacteria and biofilms in hydrothermally-influenced sediments from the Barberton greenstone belt, South Africa

Cited by 310 publications

References 45 publications

Triassic origin and early radiation of multicellular volvocine algae

Triassic origin and early radiation of multicellular volvocine algae

Fossil evidence of Archaean life

The neomuran origin of archaebacteria, the negibacterial root of the universal tree and bacterial megaclassification.

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