C value and cell volume: their significance in the evolution and development of amphibians.

Cell volume has been determined in 18 species of amphibian, ranging in C value from 1.4 pg to 62 pg DNA. There is a strong linear relationship between C value and both erythrocyte volume and erythrocyte nuclear volume. We have collected data on the timing of early embryogenesis from fertilization of the egg to the hatching tadpole in some amphibians ranging in C value from 1.4 pg to 83 pg. The species with large genomes take up to 24 times longer to reach a comparable state of development. Polyploid species develop faster than closely related diploid species. These data are discussed in relation to genome expansion and increase in cell cycle time as factors in the evolution of the Amphibia.