GENOME SIZE AND GC-PERCENT IN VERTEBRATES AS DETERMINED BY FLOW-CYTOMETRY - THE TRIANGULAR RELATIONSHIP

Genome size and GC-percent mere determined by means of a special metho d of DNA now cytometry in 154 vertebrate species. For the total datase t, a highly significant positive correlation was found between both pa rameters. The overall distribution of points is not linear but triangu lar: a wide range of GC-percent values is observed at the lower end of genome size range, whereas with an increase in genome size the lower limit for GC-percent is elevated,gradually approaching the upper Limit (about 46%). In teleost fishes, which occupy the lower part of genome size range, the negative relationship between both parameters was obs erved Two positive Linear relationships were found between mean genome size and GC-percent of the main vertebrate groups (one includes fishe s, amphibians, and mammals, the other consists of reptiles and birds, which show the higher GC-percent for their genome sizes). Distribution of variance between taxonomic levels indicates that GC-percent is mor e evolutionarily conservative than genome size in anamniotes. Anuran a mphibians show the greatest part of genome size variability at the low er taxonomic levels as compared to other vertebrates (with no addition al variance already above the genus level). The data obtained with dif ferent methods are compared. It is shown that the proposed method can provide useful data for studies on genome evolution and biodiversity. (C) 1998 Wiley-Liss, Inc.