Genome size of some selachian fishes

The nuclear DNA content of 23 chondrich- thyan species (9 Squalomorphii, 11 Batoidea and 3 Galeomorphii) has been studied. Their genome size ranged from 5.4 pg/N in Raja clavata (Batoidea) to 32.3 pg in Ëtmoplerus spinax (Squalomorphii). The lowest values so far recorded for selachians have been reported within the Batoidea, with a slight interspecific variability at the intrafamilial level. In contrast, the Squalomorphii displayed a high DNA content, with values mostly above those of all the other selachians hitherto assayed, and with a wide interspecific variability at the intrafamilial level. The results are discussed in relation to the data for other Chondrichthyes, and comparison is made with the genome size in other vertebrate classes. © 1980 Taylor and Francis Group, LLC