The role of marine biota in the evolution of terrestrial biota: Gases and genes

Author: RAVEN J.A.

Source: Biogeochemistry, Volume 39, Number 2, November 1997 , pp. 139-164(26)

Publisher: Springer

Abstract:

There is greater biodiversity (in the sense of genetic distance among higher taxa) of extant marine than of terrestrial O_2-evolvers. In addition to contributing the genes from one group of algae (Class Charophyceae, Division Chlorophyta) to produce by evolution the dominant terrestrial plants (Embryophyta), the early marine O_2-evolvers greatly modified the atmosphere and hence the land surface when the early terrestrial O_2-evolvers grew. The earliest terrestrial phototrophs (from geochemical evidence) occurred 1.2 Ga ago, over 0.7 Ga before the Embryophyta evolved, but well after the earliest marine (cyanobacterial) O_2 evolvers (3.45 Ga) and marine eukaryotic O_2 evolvers (2.1 Ga). Even by the time of evolution of the earliest terrestrial O_2-evolvers the marine O_2-evolvers had modified the atmosphere and land environment in at least the following five ways. Once photosynthetic O_2 paralleling organic C burial had satisfied marine (Fe^2+, S^2-) reductants, atmospheric O_2 built (1) up to a considerable fraction of the extant value (although some was consumed in oxidising terrestrial exposed Fe^2+) and (2) provided stratospheric O_3 and thus a UV-screen. (3) CO_2 drawdown to 20–30 times the extant level is attributable to net production, and burial, of organic C in the oceans (plus other geological processes). Furthermore, (4) their production of volatile organic S compounds could have helped to supply S to inland sites but also (5) delivered Cl and Br to the stratosphere thus lowering the O_3 level and the extent of UV screening.

Keywords: atmospheric composition; elemental composition; evolution; marine biota; soils; terrestrial biota

Language: English

Document Type: Regular paper

Affiliations: 1: Department of Biological Sciences, University of Dundee, Dundee DD1 4HN, UK

Publication date: 1997-11-01

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• In this Subject: Anatomy & Physiology ,  Biology ,  Geology
• By this author: RAVEN J.A.

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