The influence of UV radiation on protistan evolution.
Ultraviolet radiation has provided an evolutionary challenge to life on Earth. Recent increases in surficial ultraviolet B fluxes have focused attention on the role of UV radiation in protistan ecology, cancer, and DNA damage. Exploiting this new wealth of data, I examine the possibility that ultraviolet radiation may have played a significant role in the evolution of the first eukaryotes, that is, protists. Protists probably arose well before the formation of a significant ozone shield, and thus were probably subjected to substantial ultraviolet A, ultraviolet B, and ultraviolet C fluxes early in their evolution. Evolution consists of the generation of heritable variations and the subsequent selection of these variants. Ultraviolet radiation has played a role both as a mutagen and as a selective agent. In its role as a mutagen, it may have been crucial in the origin of sex and as a driver of molecular evolution. As a selective agent, its influence has been broad. Discussed in this paper are the influence of ultraviolet radiation on biogeography, photosynthesis, and desiccation resistance.
Rothschild
L J
LJ
Ecosystem Science and Technology Branch, NASA Ames Research Center, Moffett Field, California 94035-1000, USA. lrothschild@mail.arc.nasa.gov
D000818:Animals; D005075:Biological Evolution; D004249:DNA Damage; D004260:DNA Repair; D005057:Eukaryotic Cells / Q000528:radiation effects*; D019143:Evolution, Molecular; D018535:Mars; D009154:Mutation; D010788:Photosynthesis; D011387:Prokaryotic Cells / Q000528:radiation effects*; D012723:Sex; D014466:Ultraviolet Rays