An attempt to reconstruct evolutionary changes in the cellular DNA content of lungfish

✍ Scribed by Thomson, Keith Stewart

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 578 KB
• Volume: 180
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1401800307

✦ Synopsis

Living lungfish (Osteichthyes: Dipnoi) are known to have a very large cell size and unusually large quantitites of DNA per cell (up to 40 times the mammalian content). The pattern of evolution of cell size in fossil Dipnoi has been examined in order to see what light i t might possibly shed on the question of the origin and evolutionary significance of DNA multiplication in Dipnoi. In the Devonian, cell size was low and it increased only in the Carboniferous when the major dipnoan morphological and taxonomic diversifications were ebbing. If it can be shown that there is a functional relationship between cell size and DNA content, then the data suggest that increase in cellular DNA content have a retarding rather than stimulating effect on dip noan evolution. Since large cell size and (by inference) high cellular DNA content are not a primary feature of the dipnoan stock, i t is suggested that in those other vertebrates, such as certain amphibians, which show the same phenomenon, it is also a secondary feature.