MOLECULAR PHYLOGENY OF RODENTIA IN THE DESCENT OF GENUS BANDICOTA

The interrelationships of murids and other rodent families as well as the evolutionary descent of multiple beta-globins of murines are deduced from parsimony trees of relevant globin sequences. Our results show that Caviidae arises first, followed by Sciuridae which joins Muridae. In the murid line of descent Spalacinae arises first followed by two branches, one representing Cricentinae and Arvicolinae and the other Murinae. Although the rates of evolution of globin genes in the different rodent families are different, the murid branches show more or less a uniform rate of evolution of beta-globins. We have used this information to show that mouse-rat divergence occurred around 20 million years ago. The evolutionary rationale for the presence and the expression of different beta-globin genes in murid populations is also discussed. Based on mitochondrial DNA restriction fragment analysis, the between-species relationships of Rattus rattus rufescens, Bandicota indica and Bandicota bengalensis have been assessed and the time of divergence of the two bandicoot rats estimated.